Sample records for top quark mass

  1. Top quark mass measurements

    SciTech Connect (OSTI)

    Hill, Christopher S.; /UC, Santa Barbara

    2004-12-01T23:59:59.000Z

    The top quark, with its extraordinarily large mass (nearly that of a gold atom), plays a significant role in the phenomenology of EWSB in the Standard Model. In particular, the top quark mass when combined with the W mass constrains the mass of the as yet unobserved Higgs boson. Thus, a precise determination of the mass of the top quark is a principal goal of the CDF and D0 experiments. With the data collected thus far in Runs 1 and 2 of the Tevatron, CDF and D0 have measured the top quark mass in both the lepton+jets and dilepton decay channels using a variety of complementary experimental techniques. The author presents an overview of the most recent of the measurements.

  2. Top quark mass measurements

    SciTech Connect (OSTI)

    L. Cerrito

    2004-07-16T23:59:59.000Z

    Preliminary results on the measurement of the top quark mass at the Tevatron Collider are presented. In the dilepton decay channel, the CDF Collaboration measures m{sub t} = 175.0{sub -16.9}{sup +17.4}(stat.){+-}8.4(syst.) GeV/c{sup 2}, using a sample of {approx} 126 pb{sup -1} of proton-antiproton collision data at {radical}s = 1.96 TeV (Run II). In the lepton plus jets channel, the CDF Collaboration measures 177.5{sub -9.4}{sup +12.7}(stat.) {+-} 7.1(syst.) GeV/c{sup 2}, using a sample of {approx} 102 pb{sup -1} at {radical}s = 1.96 TeV. The D0 Collaboration has newly applied a likelihood technique to improve the analysis of {approx} 125 pb{sup -1} of proton-antiproton collisions at {radical}s = 1.8 TeV (Run I), with the result: m{sub t} = 180.1 {+-} 3.6(stat.) {+-}3.9(syst.) GeV/c{sup 2}. The latter is combined with all the measurements based on the data collected in Run I to yield the most recent and comprehensive experimental determination of the top quark mass: m{sub t} = 178.0 {+-} 2.7(stat.) {+-} 3.3(syst.) GeV/c{sup 2}.

  3. Top Quark Mass Measurements at the Tevatron

    E-Print Network [OSTI]

    Zhenyu Ye; for CDF; D0 collaborations

    2011-07-22T23:59:59.000Z

    We report the latest results on the top-quark mass and on the top-antitop mass difference from the CDF and D0 collaborations using data collected at the Fermilab Tevatron $p\\bar{p}$ collider at $\\sqrt{s}=1.96$ TeV. We discuss general issues in top-quark mass measurements and present new results from direct measurements and from top-pair production cross-section. We also report new results on the top-antitop mass difference.

  4. Top Quark Mass Measurements at the Tevatron

    SciTech Connect (OSTI)

    Ye, Zhenyu; /Fermilab

    2011-07-01T23:59:59.000Z

    We report the latest results on the top-quark mass and on the top-antitop mass difference from the CDF and D0 collaborations using data collected at the Fermilab Tevatron p{bar p} collider at {radical}s = 1.96 TeV. We discuss general issues in top-quark mass measurements and present new results from direct measurements and from top-pair production cross-section. We also report new results on the top-antitop mass difference.

  5. Top quark mass and properties at the Tevatron

    E-Print Network [OSTI]

    J. -F. Arguin; for the CDF; D0 Collaborations

    2005-07-29T23:59:59.000Z

    We present recent analyses of top quark properties performed at Run II of the Tevatron. Measurements of the top quark mass, branching ratios and W boson helicity inside top quark decays are covered.

  6. Top quark mass measurements at the LHC

    E-Print Network [OSTI]

    Fuster, Juan; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    The latest measurements of the top quark mass using the ATLAS and CMS experiments at the LHC are presented. The discussion includes the results obtained using the conventional methods (Template/Ideogram) and those derived from the so called alternative methods. Results from the conventional methods using the various top final states (lepton+jets, di-lepton and full hadronic) are reviewed. Determinations using the inclusive ttbar production, the ttbar production with an additional jet and the lepton-b-jet invariant mass distribution are also discussed.

  7. Tevatron Top-Quark Combinations and World Top-Quark Mass Combination

    E-Print Network [OSTI]

    Reinhild Yvonne Peters; on behalf of the ATLAS; CDF; CMS; D0 collaborations

    2014-11-04T23:59:59.000Z

    Almost 20 years after its discovery, the top quark is still an interesting particle, undergoing precise investigation of its properties. For many years, the Tevatron proton antiproton collider at Fermilab was the only place to study top quarks in detail, while with the recent start of the LHC proton proton collider a top quark factory has opened. An important ingredient for the full understanding of the top quark is the combination of measurements from the individual experiments. In particular, the Tevaton combinations of single top-quark cross sections, the ttbar production cross section, the W helicity in top-quark decays as well as the Tevatron and the world combination of the top-quark mass are discussed.

  8. CDF/PHYS/TOP/PUBLIC/7303 Measurement of the Top Quark Mass

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/PHYS/TOP/PUBLIC/7303 Measurement of the Top Quark Mass using the Neutrino Weighting Algorithm the top quark mass using 46 t #22; t candidate events in which both W bosons from top quarks decay events according to the t #22; t decay hypothesis and we measure a top mass of 170:6 +7:1 6:6 (stat) #6

  9. CDF/ANAL/TOP/PUB/7680 Measurement of the Top Quark Mass using the Template Method

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/ANAL/TOP/PUB/7680 Measurement of the Top Quark Mass using the Template Method in the Lepton, 2005) We report a measurement of the top quark mass in the lepton plus jets channel of t¯t events from, which brings 138 t¯t candidates separated into four subsamples. A top quark mass is reconstructed

  10. Top quark mass measurements at the D0 experiment

    E-Print Network [OSTI]

    Alexander Grohsjean

    2009-05-30T23:59:59.000Z

    The most recent measurements of the top quark mass at the D0 experiment are summarized. Different techniques and final states are used and the top quark mass is determined to be mtop=172.8+-1.6(stat+syst)GeV/c^2. In addition, a new, indirect measurement comparing the measured cross section to theoretical calculations is discussed. Both, the direct and the indirect measurement of the top quark mass are in good agreement.

  11. Top-quark mass measurements: Alternative techniques (LHC + Tevatron)

    E-Print Network [OSTI]

    Stefanie Adomeit

    2014-11-28T23:59:59.000Z

    Measurements of the top-quark mass employing alternative techniques are presented, performed by the D0 and CDF collaborations at the Tevatron as well as the ATLAS and CMS experiments at the LHC. The alternative methods presented include measurements using the lifetime of $B$-hadrons, the transverse momentum of charged leptons and the endpoints of kinematic distributions in top quark anti-quark pair ($t\\bar{t}$) final states. The extraction of the top-quark pole mass from the $t\\bar{t}$ production cross-section and the normalized differential $t\\bar{t}$ + 1-jet cross-section are discussed as well as the top-quark mass extraction using fixed-order QCD predictions at detector level. Finally, a measurement of the top-quark mass using events enhanced in single top t-channel production is presented.

  12. Measurement of the Top Quark Mass With 2012 CMS Data

    E-Print Network [OSTI]

    Richard Nally

    2014-09-01T23:59:59.000Z

    The mass of the top quark was an active topic of research at CMS using 2011 data, and remains so as the 2012 data analysis campaign proceeds. Here we discuss some of the earliest results on the top mass using 2012 sqrt(s) = 8 TeV CMS data, including measurements of the top mass from semileptonic t\\bar{t} decays and the lifetime of the B-hadron, as well as a measurement of the top-antitop mass difference.

  13. CDF/ANAL/TOP/PUB/7153 Measurement of the Top Quark Mass using the Template Method

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/ANAL/TOP/PUB/7153 Measurement of the Top Quark Mass using the Template Method in the Lepton of the top quark mass in the lepton plus jets channel of t #22; t events from p#22;p collisions at p s = 1; t candidates with at least one identi#12;ed b jet. A top quark mass is reconstructed for each event by using

  14. Precision Top-Quark Mass Measurement at CDF

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present a precision measurement of the top-quark mass using the full sample of Tevatron ?s=1.96??TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of ...

  15. Measurements of the top quark mass at the Tevatron

    SciTech Connect (OSTI)

    Brandt, Oleg; /Gottingen U., II. Phys. Inst.

    2012-04-01T23:59:59.000Z

    The mass of the top quark (m{sub top}) is a fundamental parameter of the standard model (SM). Currently, its most precise measurements are performed by the CDF and D0 collaborations at the Fermilab Tevatron p{bar p} collider at a centre-of-mass energy of {radical}s = 1.96 TeV. We review the most recent of those measurements, performed on data samples of up to 8.7 fb{sup -1} of integrated luminosity. The Tevatron combination using up to 5.8 fb{sup -1} of data results in a preliminary world average top quark mass of m{sub top} = 173.2 {+-} 0.9 GeV. This corresponds to a relative precision of about 0.54%. We conclude with an outlook of anticipated precision the final measurement of m{sub top} at the Tevatron.

  16. Top quark mass measurement using the template method at CDF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T [Helsinki Inst. of Phys.; Alvarez Gonzalez, B [Oviedo U.; Cantabria Inst. of Phys.; Amerio, S [INFN, Padua; Amidei, D [Michigan U.; Anastassov, A [Northwestern U.; Annovi, A [Frascati; Antos, J [Comenius U.; Apollinari, G [Fermilab; Appel, J A [Fermilab; Apresyan, A [Purdue U.; Arisawa, T [Waseda U.; Dubna, JINR

    2011-06-03T23:59:59.000Z

    We present a measurement of the top quark mass in the lepton+jets and dilepton channels of tt? decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb-1 of pp? collisions at Tevatron with ?s = 1.96 TeV, collected with the CDF II detector. The measurement is performed by constructing templates of three kinematic variables in the lepton+jets and two kinematic variables in the dilepton channel. The variables are two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from the W decay in the lepton+jets channel, and a reconstructed top quark mass and mT2, a variable related to the transverse mass in events with two missing particles, in the dilepton channel. The simultaneous fit of the templates from signal and background events in the lepton+jets and dilepton channels to the data yields a measured top quark mass of Mtop = 172.11.1 (stat)0.9 (syst) GeV/c2.

  17. Top quark mass measurement using the template method at CDF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; et al

    2011-06-03T23:59:59.000Z

    We present a measurement of the top quark mass in the lepton+jets and dilepton channels of tt? decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb-1 of pp? collisions at Tevatron with ?s = 1.96 TeV, collected with the CDF II detector. The measurement is performed by constructing templates of three kinematic variables in the lepton+jets and two kinematic variables in the dilepton channel. The variables are two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from the W decay in the lepton+jets channel, and amorereconstructed top quark mass and mT2, a variable related to the transverse mass in events with two missing particles, in the dilepton channel. The simultaneous fit of the templates from signal and background events in the lepton+jets and dilepton channels to the data yields a measured top quark mass of Mtop = 172.11.1 (stat)0.9 (syst) GeV/c2.less

  18. Measurement of the top quark mass in the dilepton channel

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Agelou, M.; Aguilo, E.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; /Buenos Aires U. /Rio de Janeiro, CBPF /Rio de Janeiro State U. /Sao Paulo, IFT /Alberta U. /Simon Fraser U. /York U., Canada /McGill U. /Hefei, CUST /Andes U., Bogota /Charles U.

    2006-09-01T23:59:59.000Z

    We present a measurement of the top quark mass in the dilepton channel based on approximately 370 pb{sup -1} of data collected by the D0 experiment during Run II of the Fermilab Tevatron collider. We employ two different methods to extract the top quark mass. We show that both methods yield consistent results using ensemble tests of events generated with the D0 Monte Carlo simulation. We combine the results from the two methods to obtain a top quark mass m{sub t} = 178.1 {+-} 8.2 GeV. The statistical uncertainty is 6.7 GeV and the systematic uncertainty is 4.8 GeV.

  19. Precision Top-Quark Mass Measurements at CDF

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-07-01T23:59:59.000Z

    We present a precision measurement of the top-quark mass using the full sample of Tevatron {radical}s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb{sup -1}. Using a sample of t{bar t} candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, mtop = 172.85 {+-} 0.71 (stat) {+-} 0.85 (syst) GeV/c{sup 2}.

  20. Measurements of the top quark mass at the tevatron

    E-Print Network [OSTI]

    Brandt, Oleg

    2012-01-01T23:59:59.000Z

    The mass of the top quark (\\mtop) is a fundamental parameter of the standard model (SM). Currently, its most precise measurements are performed by the CDF and D0 collaborations at the Fermilab Tevatron $p\\bar p$ collider at a centre-of-mass energy of $\\sqrt s=1.96 \\TeV$. We review the most recent of those measurements, performed on data samples of up to 8.7 \\fb\\ of integrated luminosity. The Tevatron combination using up to 5.8 fb$^{-1}$ of data results in a preliminary world average top quark mass of $m_{\\rm top} = 173.2 \\pm 0.9$ GeV. This corresponds to a relative precision of about 0.54%. We conclude with an outlook of anticipated precision the final measurement of \\mtop at the Tevatron.

  1. Measurements of the top quark mass at the tevatron

    E-Print Network [OSTI]

    Oleg Brandt; for the CDF Collaboration; for the D0 Collaboration

    2012-04-04T23:59:59.000Z

    The mass of the top quark (\\mtop) is a fundamental parameter of the standard model (SM). Currently, its most precise measurements are performed by the CDF and D0 collaborations at the Fermilab Tevatron $p\\bar p$ collider at a centre-of-mass energy of $\\sqrt s=1.96 \\TeV$. We review the most recent of those measurements, performed on data samples of up to 8.7 \\fb\\ of integrated luminosity. The Tevatron combination using up to 5.8 fb$^{-1}$ of data results in a preliminary world average top quark mass of $m_{\\rm top} = 173.2 \\pm 0.9$ GeV. This corresponds to a relative precision of about 0.54%. We conclude with an outlook of anticipated precision the final measurement of \\mtop at the Tevatron.

  2. Measurement of the top quark mass in the dilepton channel

    E-Print Network [OSTI]

    Baringer, Philip S.; Abbott, B.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.

    1999-07-14T23:59:59.000Z

    radiative corrections, the value of the top quark mass affects predic- tions of the standard model for many processes. For ex- ample, the prediction for the mass of the W boson varies by approximately 7 MeV1 for every 1 GeV change in the mass of the top... subdetectors that measure the trajectories of charged par- ticles: a vertex drift chamber, a transition radiation detector, a central drift chamber, and two forward drift chambers. These chambers also measure ionization to identify tracks from single charged...

  3. CDF/PHYS/TOP/PUBLIC/7303 Measurement of the Top Quark Mass using the Neutrino Weighting Algorithm on

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/PHYS/TOP/PUBLIC/7303 Measurement of the Top Quark Mass using the Neutrino Weighting Algorithm measure the top quark mass using 19 t ? t candidate events in which both W bosons from top quarks decay according to the t ? t decay hypothesis and we measure a top mass of 168.1 +11.0 -9.8 (stat) ± 8.6(syst) Ge

  4. Measurements of the top quark mass and decay width with the D0 detector

    SciTech Connect (OSTI)

    Ilchenko, Yuriy

    2011-11-01T23:59:59.000Z

    The top quark discovery in 1995 at Fermilab is one of the major proofs of the standard model (SM). Due to its unique place in SM, the top quark is an important particle for testing the theory and probing for new physics. This article presents most recent measurements of top quark properties from the D0 detector. In particular, the measurement of the top quark mass, the top antitop mass difference and the top quark decay width. The discovery of the top quark in 1995 confirmed the existence of a third generation of quarks predicted in the standard model (SM). Being the heaviest elementary particle known, the top quark appears to become an important particle in our understanding of the standard model and physics beyond it. Because of its large mass the top quark has a very short lifetime, much shorter than the hadronization time. The predicted lifetime is only 3.3 {center_dot} 10{sup -25}s. Top quark is the only quark whose properties can be studied in isolation. A Lorentz-invariant local Quantum Field Theory, the standard model is expected to conserve CP. Due to its unique properties, the top quark provides a perfect test of CPT invariance in the standard model. An ability to look at the quark before being hadronized allows to measure directly mass of the top quark and its antiquark. An observation of a mass difference between particle and antiparticle would indicate violation of CPT invariance. Top quark through its radiative loop correction to the W mass constrains the mass of the Higgs boson. A precise measurement of the top quark mass provides useful information to the search of Higgs boson by constraining its region of possible masses. Another interesting aspect is that the top quark's Yukawa coupling to the Higgs boson is very close to unity (0.996 {+-} 0.006). That implies it may play a special role in the electroweak symmetry breaking mechanism.

  5. Measurement of the top quark mass at D0

    SciTech Connect (OSTI)

    Petrillo, Gianluca; /Rochester U.

    2010-01-01T23:59:59.000Z

    The most recent measurements of the mass of the quark top at D0 are reviewed. The analysis methods include the direct measurement by Matrix Element and Weighting method and the indirect measurement from t{bar t} production cross section. They have been applied on different experimental signatures, all including at least one electron or muon. Measurements include from 1 to 3.6 fb{sup -1} of D0 data. The most recent combination of mass measurements from D0 and from CDF are also quoted.

  6. Top Quark Physics

    E-Print Network [OSTI]

    Erich W. Varnes

    2008-10-20T23:59:59.000Z

    A review is presented of the current experimental status of the top quark sector of the standard model. The measurements summarized include searches for electroweak single top production, the latest results on the ttbar production cross section, and searches for new physics in top quark production and decay. In addition, the recent measurement of the top quark mass to a precision of 0.7% is highlighted

  7. Top Quark Measurements in CMS

    E-Print Network [OSTI]

    Efe Yazgan; for the CMS Collaboration

    2014-09-12T23:59:59.000Z

    Measurements involving top quarks provide important tests of QCD. A selected set of top quark measurements in CMS including the strong coupling constant, top quark pole mass, constraints on parton distribution functions, top quark pair differential cross sections, ttbar+0 and >0 jet events, top quark mass studied using various kinematic variables in different phase-space regions, and alternative top quark mass measurements is presented. The evolution of expected uncertainties in future LHC runs for the standard and alternative top quark mass measurements is also presented.

  8. Measurement of the top quark mass with dilepton events selected using neuroevolution at CDF

    E-Print Network [OSTI]

    CDF Collaboration; T. Aaltonen

    2009-04-14T23:59:59.000Z

    We report a measurement of the top quark mass $M_t$ in the dilepton decay channel $t\\bar{t}\\to b\\ell'^{+}\

  9. /CDF/PHYS/TOP/PUBLIC/7781 First Measurement of the Top Quark Mass in the Lepton+Jets channel using the

    E-Print Network [OSTI]

    Quigg, Chris

    /CDF/PHYS/TOP/PUBLIC/7781 First Measurement of the Top Quark Mass in the Lepton+Jets channel using a novel method to measure the top quark mass using the transverse decay length of b-hadrons from top a competitive measurement of the top quark mass by itself, since the decay length technique is uncorrelated

  10. CDF/PHYS/TOP/PUBLIC/7245 Top Quark Mass Measurement in Non-tagged Lepton+Jets Events at CDF

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/PHYS/TOP/PUBLIC/7245 Top Quark Mass Measurement in Non-tagged Lepton+Jets Events at CDF The CDF of the top quark mass in non-tagged sample of lep- ton+4 jet events from p#22;p collisions at p s=1.96 Te as a superposition of top and W+jet events. The signal-constrained #12;t imposing a signal of 15.5#6;3.2 events

  11. Top Quark Properties

    E-Print Network [OSTI]

    Tony M. Liss

    2012-12-03T23:59:59.000Z

    I review the latest results on properties of the top quark from the Tevatron and the LHC, including results measured in $t\\bar{t}$ and single-top events on the mass, width, couplings, and spin correlations.

  12. Physics with boosted top quarks

    E-Print Network [OSTI]

    Elin Bergeaas Kuutmann

    2014-08-29T23:59:59.000Z

    The production at the LHC of boosted top quarks (top quarks with a transverse momentum that greatly exceeds their rest mass) is a promising process to search for phenomena beyond the Standard Model. In this contribution several examples are discussed of new techniques to reconstruct and identify (tag) the collimated decay topology of the boosted hadronic decays of top quarks. Boosted top reconstruction techniques have been utilized in searches for new physical phenomena. An overview is given of searches by ATLAS, CDF and CMS for heavy new particles decaying into a top and an anti-top quark, vector-like quarks and supersymmetric partners to the top quark.

  13. Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels

    SciTech Connect (OSTI)

    Fedorko, Wojciech T.; /Chicago U.

    2008-09-01T23:59:59.000Z

    The authors present the first measurement of the top quark mass using simultaneously data from two decay channels. They use a data sample of {radical}s = 1.96 TeV collisions with integrated luminosity of 1.9 fb{sup -1} collected by the CDF II detector. They select dilepton and lepton + jets channel decays of t{bar t} pairs and reconstruct two observables in each topology. They use non-parametric techniques to derive probability density functions from simulated signal and background samples. The observables are the reconstructed top quark mass and the scalar sum of transverse energy of the event in the dilepton topology and the reconstructed top quark mass and the invariant mass of jets from the W boson decay in lepton + jets channel. They perform a simultaneous fit for the top quark mass and the jet energy scale which is constrained in situ by the hadronic W boson resonance from the lepton + jets channel. Using 144 dilepton candidate events and 332 lepton + jets candidate events they measure: M{sub top} = 171.9 {+-} 1.7 (stat. + JES) {+-} 1.1 (other sys.) GeV/c{sup 2} = 171.9 {+-} 2.0 GeV/c{sup 2}. The measurement features a robust treatment of the systematic uncertainties, correlated between the two channels and develops techniques for a future top quark mass measurement simultaneously in all decay channels. Measurements of the W boson mass and the top quark mass provide a constraint on the mass of the yet unobserved Higgs boson. The Higgs boson mass implied by measurement presented here is higher than Higgs boson mass implied by previously published, most precise CDF measurements of the top quark mass in lepton + jets and dilepton channels separately.

  14. Top Quark Properties

    SciTech Connect (OSTI)

    Peters, Yvonne

    2011-12-01T23:59:59.000Z

    Since its discovery in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron collider, the top quark has undergone intensive studies. Besides the Tevatron experiments, with the start of the LHC in 2010 a top quark factory started its operation. It is now possible to measure top quark properties simultaneously at four different experiments, namely ATLAS and CMS at LHC and CDF and D0 at Tevatron. Having collected thousands of top quarks each, several top quark properties have been measured precisely, while others are being measured for the first time. In this article, recent measurements of top quark properties from ATLAS, CDF, CMS and D0 are presented, using up to 5.4 fb{sup -1} of integrated luminosity at the Tevatron and 1.1 fb{sup -1} at the LHC. In particular, measurements of the top quark mass, mass difference, foward backward charge asymmetry, t{bar t} spin correlations, the ratio of branching fractions, W helicity, anomalous couplings, color flow and the search for flavor changing neutral currents are discussed.

  15. Top Quark Properties

    E-Print Network [OSTI]

    Yvonne Peters; for the Atlas Collaboration; CDF Collaboration; CMS Collaboration; D0 Collaboration

    2011-12-02T23:59:59.000Z

    Since its discovery in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron collider, the top quark has undergone intensive studies. Besides the Tevatron experiments, with the start of the LHC in 2010 a top quark factory started its operation. It is now possible to measure top quark properties simultaneously at four different experiments, namely ATLAS and CMS at LHC and CDF and D0 at Tevatron. Having collected thousands of top quarks each, several top quark properties have been measured precisely, while others are being measured for the first time. In this article, recent measurements of top quark properties from ATLAS, CDF, CMS and D0 are presented, using up to 5.4 fb-1 of integrated luminosity at the Tevatron and 1.1 fb^-1 at the LHC. In particular, measurements of the top quark mass, mass difference, forward backward charge asymmetry, tt - spin correlations, the ratio of branching fractions, W helicity, anomalous couplings, color flow and the search for flavor changing neutral currents are discussed.

  16. Top Quark Mass in Events with two Charged Leptons at the D0 Experiment

    SciTech Connect (OSTI)

    Boline, Daniel Dooley; /Boston U.

    2010-01-01T23:59:59.000Z

    The top quark is the most massive observed fundamental subatomic particle, and at the Tevatron accelerator is produced mostly in top-antitop (t{bar t}) quark pairs from the collisions of protons and anti-protons. Each top quark decays into a bottom quark and a W boson. The W boson can then decay into a pair of quarks, or into a charged lepton and a neutrino. The various decays can be broken up into three different channels based on the number of leptons from the decay of the W bosons: all-jets (with no leptons), lepton+jets (with one lepton), and dilepton (with two leptons). This dissertation will present a measurement of the top quark mass in the dilepton channel. The dilepton channel is characterized by two leptons, two neutrinos and two b-quarks. The neutrinos are not directly observed, but their absence is felt as missing transverse momentum (p{sub T}) in the detector. The combination of two leptons and large p{sub T} produces an easily isolated signal, giving the dilepton channel a high signal over background ratio. Having two neutrinos means that we cannot know what the transverse momenta of either neutrino is. This means that even if we knew the momenta of the leptons and b-quarks perfectly, we would be unable to reconstruct the mass of the top quark. This measurement gets around this problem by scanning over all possible values of the top mass, finding all consistent t{bar t} combinations, assigning a kinematic weight to each, and then adding the weights for each combination at a given possible top mass. The lepton momenta, jet momenta, and p{sub T} are only known to within some finite precision, so for a given top mass, I also vary each of these momenta within their resolutions and add the weights for a given possible top mass. After scanning over possible top masses, I choose the top mass with the largest sum of weights m{sub t}{sup max} as an observable for the event. I then perform a template based likelihood fit of m{sub t} using m{sub t}{sup max}. I analyze 322 candidate events collected by the D0 detector, and obtain a top quark mass of: m{sub t} = 174.8 {+-} 3.1 GeV.

  17. /CDF/PHYS/TOP/PUBLIC/8133 Measurement of the Top Quark Mass in the Lepton+Jets channel using the Decay

    E-Print Network [OSTI]

    Quigg, Chris

    /CDF/PHYS/TOP/PUBLIC/8133 Measurement of the Top Quark Mass in the Lepton+Jets channel using present an updated measurement of the top quark mass using the transverse decay length of b- hadrons from top decays. This technique relies solely on tracking and thus avoids the jet energy scale uncertainty

  18. Top-quark mass measurement using events with missing transverse energy and jets at CDF

    SciTech Connect (OSTI)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Anastassov, A; Amidei, D; Antos, J; Annovi, A

    2013-07-01T23:59:59.000Z

    We present a measurement of the top-quark mass with tt? events using a data sample corresponding to an integrated luminosity of 5.7 fb -1 of pp? collisions at the Fermilab Tevatron with ?s = 1.96 TeV and collected by the CDF II Detector. We select events having no identified charged leptons, large missing transverse energy, and four, five, or six jets with at least one jet containing a secondary vertex consistent with the decay of a b quark. This analysis considers events from the semileptonic tt? decay channel, including events that contain tau leptons, which are usually not included in the top-quark mass measurements. The measurement uses as kinematic variables the invariant mass of two jets consistent with the mass of the W boson, and the invariant masses of two different three-jet combinations. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of Mtop = 172.3 2.4 (stat) 1.0 (syst) GeV/c2.

  19. New method for precise determination of top quark mass at LHC

    E-Print Network [OSTI]

    Kawabata, Sayaka

    2015-01-01T23:59:59.000Z

    Current measurements of the top quark mass which have achieved a precision of less than 1 GeV involve a theoretical problem that the definition of the measured mass is ambiguous in perturbation theory. As a possible solution to the problem, we present a new method to measure the top quark mass at the LHC. This method uses lepton energy distribution and has a boost-invariant nature. We discuss strategies towards a precise determination of theoretically well-defined top quark masses such as the MSbar mass with the method. As a first step in this direction, a simulation analysis at the leading order is performed considering actual experimental circumstances. The result indicates that this method with further improvements is capable of realizing a precision of less than 1 GeV at the LHC.

  20. Measurement of the top quark mass using the invariant mass of lepton pairs in soft muon b-tagged events

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present the first measurement of the mass of the top quark in a sample of tt? ???? bb? qq? events (where ?=e,?) selected by identifying jets containing a muon candidate from the semileptonic decay of heavy-flavor hadrons ...

  1. Top-quark mass measurement using events with missing transverse energy and jets at CDF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Anastassov, A; Amidei, D; Antos, J; Annovi, A

    2013-07-01T23:59:59.000Z

    We present a measurement of the top-quark mass with tt? events using a data sample corresponding to an integrated luminosity of 5.7 fb -1 of pp? collisions at the Fermilab Tevatron with ?s = 1.96 TeV and collected by the CDF II Detector. We select events having no identified charged leptons, large missing transverse energy, and four, five, or six jets with at least one jet containing a secondary vertex consistent with the decay of a b quark. This analysis considers events from the semileptonic tt? decay channel, including events that contain tau leptons, which are usually not included inmorethe top-quark mass measurements. The measurement uses as kinematic variables the invariant mass of two jets consistent with the mass of the W boson, and the invariant masses of two different three-jet combinations. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of Mtop = 172.3 2.4 (stat) 1.0 (syst) GeV/c2.less

  2. Top-quark mass measurement using events with missing transverse energy and jets at CDF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Anastassov, A; Amidei, D; Antos, J; Annovi, A

    2013-07-01T23:59:59.000Z

    We present a measurement of the top-quark mass with tt? events using a data sample corresponding to an integrated luminosity of 5.7 fb -1 of pp? collisions at the Fermilab Tevatron with ?s = 1.96 TeV and collected by the CDF II Detector. We select events having no identified charged leptons, large missing transverse energy, and four, five, or six jets with at least one jet containing a secondary vertex consistent with the decay of a b quark. This analysis considers events from the semileptonic tt? decay channel, including events that contain tau leptons, which are usually not included in the top-quark mass measurements. The measurement uses as kinematic variables the invariant mass of two jets consistent with the mass of the W boson, and the invariant masses of two different three-jet combinations. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of Mtop = 172.3 2.4 (stat) 1.0 (syst) GeV/c2.

  3. Measurement of the Top Quark Mass in Dileptonic Top Quark Pair Decays with $\\mathbf{\\sqrt{s}=7}$~TeV ATLAS Data

    E-Print Network [OSTI]

    Maier, Andreas Alexander; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    The top quark mass in dileptonic top quark pair decays was measured using $4.7~\\mathrm{fb}^{-1}$ of $\\sqrt{s}=7~\\mathrm{TeV}$ proton-proton ($pp$) collision data recorded by the ATLAS experiment at the LHC in 2011. The event topology is characterised by the presence of two charged leptons, at least two neutrinos and several jets, two of which originate from bottom quarks. Using the template method and the m$_{\\ell b}$ observable, defined as the average invariant mass of the two charged lepton plus $b$-jet pairs in each event, the top quark mass is measured to be $173.09 \\pm 0.64~(\\mathrm{stat}) \\pm 1.50~(\\mathrm{syst})~\\mathrm{GeV}$. This proceeding is based on a preliminary result, which has been superseded meanwhile.

  4. Precise measurement of the top-quark mass from lepton+jets events at D0

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U.; Augustana Coll., Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Ancu, Lucian Stefan [Nijmegen U.; Fermilab

    2011-08-09T23:59:59.000Z

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; ? tt? data corresponding to 2.6 fb-1 of integrated luminosity collected at the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an in situ jet energy calibration with the standard jet energy scale derived in studies of ? + jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of mt = 176.01 1.64 GeV. Combining this result with a previous result obtained on an independent data set, we measure a top-quark mass of mt = 174.94 1.49 GeV for a total integrated luminosity of 3.6 fb-1.

  5. Precise measurement of the top-quark mass from lepton+jets events at D0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Alverson, George O; Alves, Gilvan Augusto; et al

    2011-08-09T23:59:59.000Z

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; ? tt? data corresponding to 2.6 fb-1 of integrated luminosity collected at the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an in situ jet energy calibration with the standard jet energy scale derived in studies of ? + jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of mt = 176.01 1.64 GeV. Combining this result with a previous result obtained on an independent data set, wemoremeasure a top-quark mass of mt = 174.94 1.49 GeV for a total integrated luminosity of 3.6 fb-1.less

  6. Precise measurement of the top-quark mass from lepton+jets events at D0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U.; Augustana Coll., Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Ancu, Lucian Stefan [Nijmegen U.; Fermilab

    2011-08-09T23:59:59.000Z

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; ? tt? data corresponding to 2.6 fb-1 of integrated luminosity collected at the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an in situ jet energy calibration with the standard jet energy scale derived in studies of ? + jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of mt = 176.01 1.64 GeV. Combining this result with a previous result obtained on an independent data set, we measure a top-quark mass of mt = 174.94 1.49 GeV for a total integrated luminosity of 3.6 fb-1.

  7. Two-loop Jet-Function and Jet-Mass for Top Quarks

    E-Print Network [OSTI]

    Ambar Jain; Ignazio Scimemi; Iain W. Stewart

    2008-06-16T23:59:59.000Z

    We compute the two-loop heavy quark jet-function in the heavy quark limit. This is one of the key ingredients in next-to-next-to-leading order (NNLO) and next-to-next-to-leading-log order (NNLL) computations of the invariant mass distribution of top-jets at a future e+e- collider. The shape of the top invariant mass distribution is affected by large logs which we compute at NNLL order. Exploiting the non-abelian exponentiation theorem, a definition of the top jet-mass is given which is transitive and whose renormalization group evolution is determined by the cusp-anomalous dimension to all orders in perturbation theory. Relations of the jet-mass to the pole, MSbar, and 1S masses are presented at two-loop order.

  8. Top quark mass measurement in the lepton plus jets channel using a modified matrix element method

    E-Print Network [OSTI]

    Xie, Si

    We report a measurement of the top quark mass, m_t, obtained from pp? collisions at ?s=1.96??TeV at the Fermilab Tevatron using the CDF II detector. We analyze a sample corresponding to an integrated luminosity of ...

  9. Top-Quark Mass Measurement Using Events with Missing Transverse Energy and Jets at CDF

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present a measurement of the top-quark mass using a sample of tt? events in 5.7??fb[superscript -1] of integrated luminosity from pp? collisions at the Fermilab Tevatron with ?s=1.96??TeV and collected by the CDF II ...

  10. Top quark pair production and top quark properties at CDF

    E-Print Network [OSTI]

    Chang-Seong Moon

    2014-11-01T23:59:59.000Z

    We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $|V_{tb}|$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($A_{FB}$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $t\\bar t$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.

  11. Measurement of the top quark mass in the dilepton channel using m[subscript T2] at CDF

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present measurements of the top quark mass using m[subscript T2], a variable related to the transverse mass in events with two missing particles. We use the template method applied to tt? dilepton events produced in ...

  12. Top Quark Production at the Tevatron Collider

    E-Print Network [OSTI]

    Liang Li

    2011-07-21T23:59:59.000Z

    Top quark physics has been a rich testing ground for the standard model since the top quark discovery in 1995. The large mass of top quark suggests that it could play a special role in searches for new phenomena. In this paper I provide an overview of recent top quark production cross section measurements from both CDF and D0 collaborations and also some new physics searches done in the top quark sector.

  13. Top Quark Production at the Tevatron Collider

    SciTech Connect (OSTI)

    Li, Liang; /UC, Riverside

    2011-07-01T23:59:59.000Z

    Top quark physics has been a rich testing ground for the standard model since the top quark discovery in 1995. The large mass of top quark suggests that it could play a special role in searches for new phenomena. In this paper I provide an overview of recent top quark production cross section measurements from both CDF and D0 collaborations and also some new physics searches done in the top quark sector.

  14. A measurement of the top quark mass with a matrix element method

    SciTech Connect (OSTI)

    Gibson, Adam Paul; /UC, Berkeley

    2006-12-01T23:59:59.000Z

    The authors present a measurement of the mass of the top quark. The event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. They consider a 318 pb{sup -1} dataset collected between March 2002 and August 2004. They select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. The analysis uses leading-order t{bar t} and background matrix elements along with parameterized parton showering to construct event-by-event likelihoods as a function of top quark mass. From the 63 events observed with the 318 pb{sup -1} dataset they extract a top quark mass of 172.0 {+-} 2.6(stat) {+-} 3.3(syst) GeV/c{sup 2} from the joint likelihood. The mean expected statistical uncertainty is 3.2 GeV/c{sup 2} for m{sub t} = 178 GTeV/c{sup 2} and 3.1 GeV/c{sup 2} for m{sub t} = 172.5 GeV/c{sup 2}. The systematic error is dominated by the uncertainty of the jet energy scale.

  15. Precision Measurement of the Mass of the Top Quark in p anti-p Collisions

    SciTech Connect (OSTI)

    Garcia, Carlos A.; /Rochester U.; ,

    2007-01-01T23:59:59.000Z

    We report a measurement of the mass of the top quark (m{sub top}) in p{bar p} collisions at a center of mass energy of 1.96 TeV. The analysis is based on p{bar p}{yields}t{bar t}{yields} lepton+jets data recorded with the D0 detector at the Fermilab Tevatron Collider. Events were preselected in the e+jets (913 events/pb of data) and in the {mu}+jets (871 events/pb of data) channels. These were analyzed through a comparison of the matrix element for the production and decay of the t{bar t} states with data, using a likelihood method and 'tagged' b quarks from the t {yields} Wb decays.

  16. Top quark studies at hadron colliders

    SciTech Connect (OSTI)

    Sinervo, P.K. [Univ. of Toronto, Ontario (Canada)

    1997-01-01T23:59:59.000Z

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.

  17. FermilabPub97/172E Measurement of the Top Quark Mass Using Dilepton Events

    E-Print Network [OSTI]

    collaboration has performed a measurement of the top quark mass m t based on six candidate events. We obtain m t = 168:4 \\Sigma 12:3 (stat) \\Sigma 3:7 (sys) GeV/c 2 , consistent with the measurement:0 \\Sigma 7:5 GeV/c 2 . Typeset using REVT E X \\Lambda Authors listed on the following page. Submitted

  18. Measurement of the Top Quark Mass at CDF Using the Template Method in the Lepton + Jets Channel

    SciTech Connect (OSTI)

    Adelman, Jahred A.; /Chicago U.

    2008-05-01T23:59:59.000Z

    A measurement of the top quark mass in p{bar p} collisions at {radical}s = 1.96 TeV is presented. The analysis uses a template method, in which the overconstrained kinematics of the Lepton+Jets channel of the t{bar t} system are used to measure a single quantity, the reconstructed top quark mass, that is strongly correlated with the true top quark mass. in addition, the dijet mass of the hadronically decaying W boson is used to constrain in situ the uncertain jet energy scale in the CDF detector. Two-dimensional probability density functions are derived using a kernel density estimate-based machinery. Using 1.9 fb{sup -1} of data, the top quark mass is measured to be 171.8{sub -1.9}{sup +1.9}(stat.) {+-} 1.0(syst.)GeV/c{sup 2}.

  19. Measurement of the Top Quark Mass From Dileptonic $t\\bar{t}$ Decays With 2012 CMS Data

    E-Print Network [OSTI]

    Richard Nally; for the CMS Collaboration

    2014-11-26T23:59:59.000Z

    We present a measurement of the top quark mass using 19.7 $\\pm$ 0.5 fb$^{-1}$ of $\\sqrt{s} = 8$ TeV CMS data. In particular, we study dileptonic $t\\bar{t}$ decays, in which a top-antitop pair decays to a final state containing two electrons or muons. We use the Analytical Matrix Weighting Technique (AMWT), and have performed the first blind top mass measurement at CMS. The mass of the top quark is measured as $m_t = 172.47 \\pm 0.17(\\text{stat}) \\pm 1.40(\\text{syst})$ GeV.

  20. A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II

    E-Print Network [OSTI]

    Quigg, Chris

    , Stephen Miller, Fred Niell, Tom Schwarz, Tom Wright and Alexei Varganov. The top group and top mass group

  1. Top quark in theory

    E-Print Network [OSTI]

    Eric Laenen

    2008-09-18T23:59:59.000Z

    I review how the top quark is embedded in the Standard Model and some its proposed extensions, and how it manifests itself in various hadron collider signals.

  2. Top Quark Highlights

    E-Print Network [OSTI]

    Christian Schwanenberger

    2010-04-28T23:59:59.000Z

    Highlights of top quark physics presented at the 2009 Europhysics Conference on High Energy Physics from 16-22 July 2009 in Krakow, Poland, are reviewed.

  3. Higgs boson mass and high-luminosity LHC probes of supersymmetry with vectorlike top quark

    E-Print Network [OSTI]

    Lalak, Zygmunt; Wells, James D

    2015-01-01T23:59:59.000Z

    We consider an extension of the MSSM with an added vectorlike top partner. Our aim is to revisit to what extent such an extension can raise the Higgs boson mass through radiative corrections and help ameliorate the MSSM hierarchy problem, and to specify what experimental probes at the LHC will find or exclude this possibility during the high-luminosity phase. Direct detection, precision electroweak and precision Higgs analyses are all commissioned to this end. To achieve the $ 125 \\, \\textrm{GeV} \\ $ Higgs boson mass, we find that superpartner masses can be reduced by a factor of more than three in this scenario compared to the MSSM without the extra vectorlike top quark, and that during the high-luminosity phase of the LHC precision Higgs analysis is expected to become the most powerful experimental probe of the scenario.

  4. Independent measurement of the top quark mass and the light- and bottom-jet energy scales at hadron colliders

    E-Print Network [OSTI]

    Frank Fiedler

    2007-06-12T23:59:59.000Z

    A method for the simultaneous determination of the energy scales for b-quark jets and light jets, the jet energy resolution, and the top quark mass at hadron colliders is presented. The method exploits the unique kinematics of events with top-antitop pair production, where one of the top quarks involves a leptonic and one a hadronic W boson decay. The paper shows a feasibility study of how this simultaneous measurement can be performed at the upcoming LHC experiments ATLAS and CMS.

  5. Properties of the top quark

    E-Print Network [OSTI]

    A. W. Jung

    2014-10-14T23:59:59.000Z

    Recent measurements of top-quark properties at the LHC and the Tevatron are presented. Most recent measurements of the top quark mass have been carried out by CMS using $19.7/$fb of $\\sqrt{s} = 8$ TeV data including the study of the dependence on event kinematics. ATLAS uses the full Run I data at $\\sqrt{s} = 7$ TeV for a "3D" measurement that significantly reduces systematic uncertainties. D0 employs the full Run II data using the matrix element method to measure the top quark mass with significantly reduced systematic uncertainties. Many different measurements of the top quark exist to date and the most precise ones per decay channel per experiment have been combined into the first world combination with a relative precision of 0.44%. Latest updates of measurements of production asymmetries include the measurement of the \\ttbar production asymmetry by D0 employing the full Run II data set, by CMS and ATLAS (including the polarization of the top quark) employing both the full data set at $\\sqrt{s} = 7$ TeV. CMS uses the full $\\sqrt{s} = 8$ TeV data to measure the top quark polarization in single top production, the ratio ${\\cal R}$ of the branching fractions ${\\cal B}(t \\rightarrow Wb) / {\\cal B}(t \\rightarrow Wq)$ and to search for flavor changing neutral currents. The results from all these measurements agree well with their respective Standard Model expectation.

  6. Measurement of the Top-Quark Mass in the All-Hadronic Channel using the full CDF data set

    E-Print Network [OSTI]

    CDF Collaboration; T. Aaltonen; S. Amerio; D. Amidei; A. Anastassov; A. Annovi; J. Antos; G. Apollinari; J. A. Appel; T. Arisawa; A. Artikov; J. Asaadi; W. Ashmanskas; B. Auerbach; A. Aurisano; F. Azfar; W. Badgett; T. Bae; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; P. Barria; P. Bartos; M. Bauce; F. Bedeschi; S. Behari; G. Bellettini; J. Bellinger; D. Benjamin; A. Beretvas; A. Bhatti; K. R. Bland; B. Blumenfeld; A. Bocci; A. Bodek; D. Bortoletto; J. Boudreau; A. Boveia; L. Brigliadori; C. Bromberg; E. Brucken; J. Budagov; H. S. Budd; K. Burkett; G. Busetto; P. Bussey; P. Butti; A. Buzatu; A. Calamba; S. Camarda; M. Campanelli; F. Canelli; B. Carls; D. Carlsmith; R. Carosi; S. Carrillo; B. Casal; M. Casarsa; A. Castro; P. Catastini; D. Cauz; V. Cavaliere; M. Cavalli-Sforza; A. Cerri; L. Cerrito; Y. C. Chen; M. Chertok; G. Chiarelli; G. Chlachidze; K. Cho; D. Chokheli; A. Clark; C. Clarke; M. E. Convery; J. Conway; M. Corbo; M. Cordelli; C. A. Cox; D. J. Cox; M. Cremonesi; D. Cruz; J. Cuevas; R. Culbertson; N. d'Ascenzo; M. Datta; P. de Barbaro; L. Demortier; L. Marchese; M. Deninno; F. Devoto; M. D'Errico; A. Di Canto; B. Di Ruzza; J. R. Dittmann; M. D'Onofrio; S. Donati; M. Dorigo; A. Driutti; K. Ebina; R. Edgar; A. Elagin; R. Erbacher; S. Errede; B. Esham; S. Farrington; J. P. Fernndez Ramos; R. Field; G. Flanagan; R. Forrest; M. Franklin; J. C. Freeman; H. Frisch; Y. Funakoshi; C. Galloni; A. F. Garfinkel; P. Garosi; H. Gerberich; E. Gerchtein; S. Giagu; V. Giakoumopoulou; K. Gibson; C. M. Ginsburg; N. Giokaris; P. Giromini; G. Giurgiu; V. Glagolev; D. Glenzinski; M. Gold; D. Goldin; A. Golossanov; G. Gomez; G. Gomez-Ceballos; M. Goncharov; O. Gonzlez Lpez; I. Gorelov; A. T. Goshaw; K. Goulianos; E. Gramellini; S. Grinstein; C. Grosso-Pilcher; R. C. Group; J. Guimaraes da Costa; S. R. Hahn; J. Y. Han; F. Happacher; K. Hara; M. Hare; R. F. Harr; T. Harrington-Taber; K. Hatakeyama; C. Hays; J. Heinrich; M. Herndon; A. Hocker; Z. Hong; W. Hopkins; S. Hou; R. E. Hughes; U. Husemann; M. Hussein; J. Huston; G. Introzzi; M. Iori; A. Ivanov; E. James; D. Jang; B. Jayatilaka; E. J. Jeon; S. Jindariani; M. Jones; K. K. Joo; S. Y. Jun; T. R. Junk; M. Kambeitz; T. Kamon; P. E. Karchin; A. Kasmi; Y. Kato; W. Ketchum; J. Keung; B. Kilminster; D. H. Kim; H. S. Kim; J. E. Kim; M. J. Kim; S. B. Kim; S. H. Kim; Y. K. Kim; Y. J. Kim; N. Kimura; M. Kirby; K. Knoepfel; K. Kondo; D. J. Kong; J. Konigsberg; A. V. Kotwal; M. Kreps; J. Kroll; M. Kruse; T. Kuhr; M. Kurata; A. T. Laasanen; S. Lammel; M. Lancaster; K. Lannon; G. Latino; H. S. Lee; J. S. Lee; S. Leo; S. Leone; J. D. Lewis; A. Limosani; E. Lipeles; A. Lister; H. Liu; Q. Liu; T. Liu; S. Lockwitz; A. Loginov; A. Luc; D. Lucchesi; J. Lueck; P. Lujan; P. Lukens; G. Lungu; J. Lys; R. Lysak; R. Madrak; P. Maestro; S. Malik; G. Manca; A. Manousakis-Katsikakis; F. Margaroli; P. Marino; M. Martnez; K. Matera; M. E. Mattson; A. Mazzacane; P. Mazzanti; R. McNulty; A. Mehta; P. Mehtala; C. Mesropian; T. Miao; D. Mietlicki; A. Mitra; H. Miyake; S. Moed; N. Moggi; C. S. Moon; R. Moore; M. J. Morello; A. Mukherjee; Th. Muller; P. Murat; M. Mussini; J. Nachtman; Y. Nagai; J. Naganoma; I. Nakano; A. Napier; J. Nett; C. Neu; T. Nigmanov; L. Nodulman; S. Y. Noh; O. Norniella; L. Oakes; S. H. Oh; Y. D. Oh; I. Oksuzian; T. Okusawa; R. Orava; L. Ortolan; C. Pagliarone; E. Palencia; P. Palni; V. Papadimitriou; W. Parker; G. Pauletta; M. Paulini; C. Paus; T. J. Phillips; G. Piacentino; E. Pianori; J. Pilot; K. Pitts; C. Plager; L. Pondrom; S. Poprocki; K. Potamianos; F. Prokoshin; A. Pranko; F. Ptohos; G. Punzi; N. Ranjan; I. Redondo Fernndez; P. Renton; M. Rescigno; F. Rimondi; L. Ristori; A. Robson; T. Rodriguez; S. Rolli; M. Ronzani; R. Roser; J. L. Rosner; F. Ruffini; A. Ruiz; J. Russ; V. Rusu; W. K. Sakumoto; Y. Sakurai; L. Santi; K. Sato; V. Saveliev; A. Savoy-Navarro; P. Schlabach; E. E. Schmidt; T. Schwarz; L. Scodellaro; F. Scuri; S. Seidel; Y. Seiya; A. Semenov; F. Sforza; S. Z. Shalhout; T. Shears; P. F. Shepard; M. Shimojima; M. Shochet; I. Shreyber-Tecker; A. Simonenko; K. Sliwa; J. R. Smith; F. D. Snider; V. Sorin; H. Song; M. Stancari; R. St. Denis; D. Stentz; J. Strologas; Y. Sudo; A. Sukhanov; I. Suslov; K. Takemasa; Y. Takeuchi; J. Tang; M. Tecchio; P. K. Teng; J. Thom; E. Thomson; V. Thukral; D. Toback; S. Tokar; K. Tollefson; T. Tomura; D. Tonelli; S. Torre; D. Torretta; P. Totaro; M. Trovato; F. Ukegawa; S. Uozumi; F. Vzquez; G. Velev; C. Vellidis; C. Vernieri; M. Vidal; R. Vilar; J. Vizn; M. Vogel; G. Volpi; P. Wagner; R. Wallny; S. M. Wang; D. Waters; W. C. Wester III; D. Whiteson; A. B. Wicklund; S. Wilbur; H. H. Williams; J. S. Wilson; P. Wilson; B. L. Winer; P. Wittich; S. Wolbers; H. Wolfe; T. Wright; X. Wu; Z. Wu; K. Yamamoto; D. Yamato; T. Yang; U. K. Yang; Y. C. Yang; W. -M. Yao; G. P. Yeh; K. Yi; J. Yoh; K. Yorita; T. Yoshida; G. B. Yu

    2014-10-08T23:59:59.000Z

    The top-quark mass M_top is measured using top quark-antiquark pairs produced in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV and decaying into a fully hadronic final state. The full data set collected with the CDFII detector at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 9.3 fb-1, is used. Events are selected that have six to eight jets, at least one of which is identified as having originated from a b quark. In addition, a multivariate algorithm, containing multiple kinematic variables as inputs, is used to discriminate signal events from background events due to QCD multijet production. Templates for the reconstructed top-quark mass are combined in a likelihood fit to measure M_top with a simultaneous calibration of the jet-energy scale. A value of M_top = 175.07+- 1.19(stat)+1.55-1.58(syst) GeV/c^2 is obtained for the top-quark mass.

  7. Top-Quark Physics Results From LHC

    E-Print Network [OSTI]

    Luca Fiorini

    2012-01-30T23:59:59.000Z

    The top-quark is a fundamental element of the physics program at the Large Hadron Collider (LHC). We review the current status of the top-quark measurements performed by ATLAS and CMS experiments in pp collisions at sqrt(s)=7 TeV by presenting the recent results of the top-quark production rates, top mass measurements and additional top quark properties. We will also describe the recent searches for physics beyond the Standard Model in the top-quark sector.

  8. Measurement of the mass difference between top and anti-top quarks in pp collisions at ?s = 7 TeV using the ATLAS detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb[superscript ?1] data sample of protonproton collisions at ?s = 7 TeV recorded with the ATLAS detector at the LHC, events ...

  9. Single Top Quark

    SciTech Connect (OSTI)

    Heidi Schellman and Ann Heinson

    2009-03-12T23:59:59.000Z

    Fermilab researchers Heidi Schellman and Ann Heinson take a whimsical look at the recent announcement of the discovery of the single top quark, by Fermilab's CDF and DZero experiments.

  10. Measurement of the Top Quark Mass in the Di-lepton Channel using the Dalitz-Goldstein Method

    SciTech Connect (OSTI)

    Hare, Matthew Frederick; /Tufts U.

    2010-10-01T23:59:59.000Z

    This dissertation describes a measurement of the mass of the top quark using a method developed by G. Goldstein and R.H. Dalitz. It is based on 2.0 fb{sup -1} of data collected by the Collider Detector Facility at Fermi National Accelerator Laboratories. Di-lepton events were observed from colliding protons with anti-protons with {radical}s = 1.96 TeV in the Tevatron Collider. A total of 145 candidate events were observed with 49 expected to be from background. These events include two neutrinos which elude detection. The method begins by assuming an initial top quark mass and solves for the neutrino momenta using a geometrical construction. The method samples over a range of likely top quark masses choosing the most consistent mass via a likelihood function. An important distinguishing feature of this method from others is its lack of dependence on the missing transverse energy, a quantity that is poorly measured by the experiment. This analysis determines the top quark mass to be M{sub top} = 172.3 {+-} 3.4(stat.) {+-} 2.0(syst.) GeV/c{sup 2} (M{sub top} = 170.5 {+-} 3.7(stat.) {+-} 1.8(syst.) GeV/c{sup 2} with b-tagging).

  11. Top Quark Studies at D0

    E-Print Network [OSTI]

    R. Y. Peters

    2014-08-10T23:59:59.000Z

    Years after its discovery in 1995 by CDF and D0, the top quark still undergoes intense investigations at the Tevatron. Using up to the full Run~II data sample, new measurements of top quark production and properties by the D0 Collaboration are presented. In particular, the first observation of single top quark s-channel production, the measurement of differential ttbar distributions, forward-backward ttbar asymmetry, a new measurement of the top quark mass, and a measurement of the top quark charge are discussed.

  12. Top Mass and Properties

    E-Print Network [OSTI]

    Yen-Chu Chen

    2008-05-15T23:59:59.000Z

    The top quark was discovered in 1995. The top quark mass is now well measured at the Tevatron, with uncertainty getting below 1% of the top mass. The world average from last year was 170.9 $\\pm$ 1.8 GeV/$c^2$. The new CDF measurement is 172 $\\pm$ 1.2 (stat) $\\pm$ 1.5 (sys) GeV/$c^2$, and D0 will soon present a new measurement. The top quark mass is an important parameter in the Standard Model, and should be measured as precisely as possible. To learn more about the top quark observed and study possible new physics, other properties also should be measured. At the Tevatron, the charge of the top quark can be measured directly. Examples of other properties studied and reported in this presentation are W helicity, top decay branching ratio to b ($R_b$), searches for $t \\to H b$ and for flavor changing neutral current (FCNC). The results are all consistent with the Standard Model within current statistics. With significantly more data being collected at the Tevatron, precision measurements of the top properties are just starting.

  13. CDF measurement of the top quark mass in the lepton + jets channel using the multivariate template method

    SciTech Connect (OSTI)

    Freeman, John; /Fermilab

    2004-12-01T23:59:59.000Z

    The authors measure the mass of the top quark using 162 pb{sup -1} of data collected by the CDF experiment at FNAL in Run II. The decay chain t{bar t} {yields} bq{bar q}{bar b}lv is studied using a novel technique called the Multivariate Template Method (MTM). Using this technique they obtain a result of M{sub top} = 179.6{sub -6.3}{sup +6.4} {+-} 6.8 GeV/c{sup 2} for the top quark.

  14. Top Quark Physics at the ILC: Methods and Meanings

    E-Print Network [OSTI]

    Zack Sullivan

    2009-03-06T23:59:59.000Z

    The physics case for studying top-quark physics at the International Linear Collider is well established. This summary places in context the top-quark physics goals, examines the current state-of-the art in understanding of the top-quark mass, and identifies some areas in which the study of the top-quark mass enhances our understanding of new techniques.

  15. Theory of top quark production and decay

    SciTech Connect (OSTI)

    Kuehn, J.H. [Universitaet Karlsruhe (Germany)

    1997-01-01T23:59:59.000Z

    Direct and indirect information on the top quark mass and its decay modes is reviewed. The theory of top production in hadron- and electron-positron-colliders is presented.

  16. Properties of the Top Quark

    SciTech Connect (OSTI)

    Wicke, Daniel; /Wuppertal U., Dept. Math.

    2009-08-01T23:59:59.000Z

    The aim of particle physics is the understanding of elementary particles and their interactions. The current theory of elementary particle physics, the Standard Model, contains twelve different types of fermions which (neglecting gravity) interact through the gauge bosons of three forces. In addition a scalar particle, the Higgs boson, is needed for theoretical consistency. These few building blocks explain all experimental results found in the context of particle physics, so far. Nevertheless, it is believed that the Standard Model is only an approximation to a more complete theory. First of all the fourth known force, gravity, has withstood all attempts to be included until now. Furthermore, the Standard Model describes several features of the elementary particles like the existence of three families of fermions or the quantisation of charges, but does not explain these properties from underlying principles. Finally, the lightness of the Higgs boson needed to explain the symmetry breaking is difficult to maintain in the presence of expected corrections from gravity at high scales. This is the so called hierarchy problem. In addition astrophysical results indicate that the universe consists only to a very small fraction of matter described by the Standard Model. Large fractions of dark energy and dark matter are needed to describe the observations. Both do not have any correspondence in the Standard Model. Also the very small asymmetry between matter and anti-matter that results in the observed universe built of matter (and not of anti-matter) cannot be explained until now. It is thus an important task of experimental particle physics to test the predictions of the Standard Model to the best possible accuracy and to search for deviations pointing to necessary extensions or modifications of our current theoretical understanding. The top quark was predicted to exist by the Standard Model as the partner of the bottom quark. It was first observed in 1995 by the Tevatron experiments CDF and D0 and was the last of the quarks to be discovered. As the partner of the bottom quark the top quark is expected to have quantum numbers identical to that of the other known up-type quarks. Only the mass is a free parameter. We now know that it is more than 30 times heavier than the next heaviest quark, the bottom quark. Thus, within the Standard Model all production and decay properties are fully defined. Having the complete set of quarks further allows to verify constraints that the Standard Model puts on the sum of all quarks or particles. This alone is reason enough to experimentally study the top quark properties. The high value of the top quark mass and its closeness to the electroweak scale has inspired people to speculate that the top quark could have a special role in the electroweak symmetry breaking. Confirming the expected properties of the top quark experimentally establishes the top quark as we expect it to be. Any deviation from the expectations gives hints to new physics that may help to solve the outstanding questions. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarized. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties. After a short introduction to the Standard Model and the experimental environment in the remainder of this chapter, Chapter 2 describes the current status of top quark mass measurements. Then measurments of interaction properties are described in Chapter 3. Finally, Chapter 4 deals with analyses that consider hypothetical particles beyond the Standard Model in the observed events.

  17. Top quark physics in hadron collisions

    E-Print Network [OSTI]

    Wolfgang Wagner

    2007-08-03T23:59:59.000Z

    The top quark is the heaviest elementary particle observed to date. Its large mass makes the top quark an ideal laboratory to test predictions of perturbation theory concerning heavy quark production at hadron colliders. The top quark is also a powerful probe for new phenomena beyond the Standard Model of particle physics. In addition, the top quark mass is a crucial parameter for scrutinizing the Standard Model in electroweak precision tests and for predicting the mass of the yet unobserved Higgs boson. Ten years after the discovery of the top quark at the Fermilab Tevatron top quark physics has entered an era where detailed measurements of top quark properties are undertaken. In this review article an introduction to the phenomenology of top quark production in hadron collisions is given, the lessons learned in Tevatron Run I are summarized, and first Run II results are discussed. A brief outlook to the possibilities of top quark research a the Large Hadron Collider, currently under construction at CERN, is included.

  18. Top Quark Mass Measurement in the Lepton plus Jets Channel Using a Modified Matrix Element Method

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Akimoto, T.; /Tsukuba U.; Alvarez Gonzalez, B.; /CSIC, Catalunya; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

    2008-12-01T23:59:59.000Z

    The authors report a measurement of the top quark mass, m{sub t}, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. They analyze a sample corresponding to an integrated luminosity of 1.9 rfb{sup -1}. They select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a b quark. They calculate a signal likelihood using a matrix element integration method, where the matrix element is modified by using effective propagators to take into account assumptions on event kinematics. The event likelihood is a function of m{sub t} and a parameter JES that determines in situ the calibration of the jet energies. They use a neural network discriminant to distinguish signal from background events. They also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, they find m{sub t} = 172.7 {+-} 1.8 (stat. + JES) {+-} 1.2(syst.) GeV/c{sup 2}.

  19. Top Quark Physics at the CDF Experiment

    E-Print Network [OSTI]

    Bernd Stelzer; for the CDF Collaboration

    2010-07-21T23:59:59.000Z

    Fermilab's Tevatron accelerator is recently performing at record luminosities that enables a program systematically addressing the physics of top quarks. The CDF collaboration has analyzed up to 5/fb of proton anti-proton collisions from the Tevatron at a center of mass energy of 1.96 TeV. The large datasets available allow to push top quark measurements to higher and higher precision and have lead to the recent observation of electroweak single top quark production at the Tevatron. This article reviews recent results on top quark physics from the CDF experiment.

  20. Recent Results of Top Quark Physics from the Tevatron

    E-Print Network [OSTI]

    R. Y. Peters; on behalf of the D0; CDF collaborations

    2015-07-09T23:59:59.000Z

    Twenty years after its discovery in 1995 by the CDF and D0 collaborations at the Tevatron proton-antiproton collider at Fermilab, the top quark still undergoes intensive studies at the Tevatron and the LHC at CERN. In this article, recent top quark physics results from CDF and D0 are reported. In particular, measurements of single top quark and double top quark production, the ttbar forward-backward asymmetry and the top quark mass are discussed.

  1. Top quark mass coupling and classification of weakly-coupled heterotic superstring vacua

    E-Print Network [OSTI]

    Rizos, J

    2014-01-01T23:59:59.000Z

    The quest for the Standard Model among the huge number of string vacua is usually based on a set of phenomenological criteria related to the massless spectrum of string models. In this work we study criteria associated with interactions in the effective low energy theory and in particular with the presence of the coupling that provides mass to the top quark. Working in the context of the Free Fermionic Formulation of the heterotic superstring, we demonstrate that, in a big class of phenomenologically promising $Z_2\\times Z_2$ compactifications, these criteria can be expressed entirely in terms of the generalised GSO projection coefficients entering the definition of the models. They are shown to be very efficient in identifying phenomenologically viable vacua, especially in the framework of computer-based search, as they are met by approximately one every $10^4$ models. We apply our results in the investigation of a class of supersymmetric Pati-Salam vacua, comprising $10^{16}$ configurations, and show that w...

  2. Top quark mass coupling and classification of weakly-coupled heterotic superstring vacua

    E-Print Network [OSTI]

    J. Rizos

    2014-05-25T23:59:59.000Z

    The quest for the Standard Model among the huge number of string vacua is usually based on a set of phenomenological criteria related to the massless spectrum of string models. In this work we study criteria associated with interactions in the effective low energy theory and in particular with the presence of the coupling that provides mass to the top quark. Working in the context of the Free Fermionic Formulation of the heterotic superstring, we demonstrate that, in a big class of phenomenologically promising $Z_2\\times Z_2$ compactifications, these criteria can be expressed entirely in terms of the generalised GSO projection coefficients entering the definition of the models. They are shown to be very efficient in identifying phenomenologically viable vacua, especially in the framework of computer-based search, as they are met by approximately one every $10^4$ models. We apply our results in the investigation of a class of supersymmetric Pati-Salam vacua, comprising $10^{16}$ configurations, and show that when combined with other phenomenological requirements they lead to a relatively small set of about $10^7$ Standard Model compatible models that can be fully classified.

  3. Review of Top Quark Physics Results

    SciTech Connect (OSTI)

    Kehoe, R.; Narain, M.; Kumar, A.; ,

    2007-12-01T23:59:59.000Z

    As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. Production of top quarks in pairs provides an important probe of strong interactions. The top quark mass is a key fundamental parameter which places a valuable constraint on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states constrain potential new physics. In many cases, the tests available with study of the top quark are both critical and unique. Large increases in data samples from the Fermilab Tevatron have been coupled with major improvements in experimental techniques to produce many new precision measurements of the top quark. The first direct evidence for electroweak production of top quarks has been obtained, with a resulting direct determination of V{sub tb}. Several of the properties of the top quark have been measured. Progress has also been made in obtaining improved limits on potential anomalous production and decay mechanisms. This review presents an overview of recent theoretical and experimental developments in this field. We also provide a brief discussion of the implications for further efforts.

  4. Top quark physics at CDF

    E-Print Network [OSTI]

    Karolos Potamianos

    2011-12-01T23:59:59.000Z

    We present the recent results of top-quark physics using up to 6 fb$^{-1}$ of $p\\bar{p}$ collisions analyzed by the CDF collaboration. The large number of top quark events analyzed, of the order of several thousands, allows stringent checks of the standard model predictions. Also, the top quark is widely believed to be a window to new physics. We present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  5. Top quark physics at CDF

    SciTech Connect (OSTI)

    Potamianos, Karolos

    2011-12-01T23:59:59.000Z

    We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions analyzed by the CDF collaboration. The large number of top quark events analyzed, of the order of several thousands, allows stringent checks of the standard model predictions. Also, the top quark is widely believed to be a window to new physics. We present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  6. Top Quark Mass Measurement in the lepton plus jets Channel Using a Matrix Element Method and in situ Jet Energy Calibration

    E-Print Network [OSTI]

    Bauer, Gerry P.

    A precision measurement of the top quark mass mt [m subscript t] is obtained using a sample of tt? events from pp? collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, ...

  7. Measurements of the Top-Quark Mass and the tt? Cross Section in the Hadronic ?+jets Decay Channel at ?s=1.96??TeV

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present the first direct measurement of the top-quark mass using tt? events decaying in the hadronic ?+jets decay channel. Using data corresponding to an integrated luminosity of 2.2??fb[superscript -1] collected by the ...

  8. Discovery of single top quark production

    SciTech Connect (OSTI)

    Gillberg, Dag

    2009-05-01T23:59:59.000Z

    The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking - the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. An analysis is performed using 2.3 fb{sup -1} of data recorded by the D0 detector at the Fermilab Tevatron Collider at centre-of-mass energy {radical}s = 1.96 TeV. Boosted decision trees are used to isolate the single top signal from background, and the single top cross section is measured to be {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.74{sub -0.74}{sup +0.95} pb. Using the same analysis, a measurement of the amplitude of the CKM matrix element V{sub tb}, governing how top and b quarks mix, is also performed. The measurement yields: |V{sub tb}|f{sub 1}{sup L}| = 1.05{sub -0.12}{sup +0.13}, where f{sub 1}{sup L} is the left-handed Wtb coupling. The separation of signal from background is improved by combining the boosted decision trees with two other multivariate techniques. A new cross section measurement is performed, and the significance for the excess over the predicted background exceeds 5 standard deviations.

  9. CDF/PUB/TOP/CDFR/11076 First Search for s-channel Electroweak Single Top Quark

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/PUB/TOP/CDFR/11076 First Search for s-channel Electroweak Single Top Quark Production, 2014) Abstract The first search for electroweak single top quark production from the exchange of an s-model backgrounds is observed. Assuming that this excess is due to electroweak production of top quarks of mass 172

  10. Measurements of top quark properties at the Tevatron collider

    SciTech Connect (OSTI)

    Margaroli, Fabrizio

    2011-05-01T23:59:59.000Z

    The discovery of the top quark in 1995 opened a whole new sector of investigation of the Standard Model; today top quark physics remains a key priority of the Tevatron program. Some of the measurements of top quark properties, for example its mass, will be a long-standing legacy. The recent evidence of an anomalously large charge asymmetry in top quark events suggests that new physics could couple preferably with top quarks. I will summarize this long chapter of particle physics history and discuss the road the top quark is highlighting for the LHC program.

  11. Top quark properties from the Tevatron

    SciTech Connect (OSTI)

    Klute, Markus; /MIT, LNS

    2006-05-01T23:59:59.000Z

    This report describes latest measurements and studies of top quark properties from the Tevatron in Run II with an integrated luminosity of up to 750 pb{sup -1}. Due to its large mass of about 172 GeV/c{sup 2}, the top quark provides a unique environment for tests of the Standard Model and is believed to yield sensitivity to new physics beyond the Standard Model. With data samples of close to 1 fb{sup -1} the CDF and D0 collaborations at the Tevatron enter a new area of precision top quark measurements.

  12. Top-Quark Mass Data and the Sum of Quasi-Degenerate Neutrino Masses (One small electroweak-bound e-parameter organizes elementary particle 3-flavor phenomenology)

    E-Print Network [OSTI]

    E. M. Lipmanov

    2008-10-01T23:59:59.000Z

    The absolute neutrino masses and type of neutrino mass hierarchy are among the main problems in neutrino physics. Top-quark mass is another topical problem in particle physics. These problems extend the old puzzle of electron-muon mass ratio close to the fine structure constant, which is still not solved by known theory. Here I continue the search for a general flavor pattern that may incorporate these problems. Relations between neutrino/electron and electron/top-quark pole mass ratios are obtained from supposition that realistic elementary particle dimensionless bare flavor quantities are small deviated (measured by universal parameter e) from the values of a stated flavor pattern (at e=0) and experimental data hints. With the world average t-quark mass data the sum of QD-neutrino masses is estimated (0.50 +- 0.003)eV in agreement with cosmological constraints and known QD-neutrino mass estimations from experimental data on neutrino oscillation mass-squared differences.

  13. Review of recent top-quark LHC combinations

    E-Print Network [OSTI]

    Giorgio Cortiana; on behalf of the ATLAS; CMS collaborations within the TOPLHCWG

    2014-11-27T23:59:59.000Z

    A review of recent combinations of top-quark measurements performed at the LHC, by the ATLAS and CMS collaborations, is provided. The typical uncertainty categorisations, and their assumed correlation patterns are presented, together with the results of the combinations of the top-quark pair and single top-quark production cross sections, the top-quark mass, as well as of the $W$ boson polarisation and the charge asymmetry in $t\\bar t$ events.

  14. Standard Model False Vacuum Inflation: Correlating the Tensor-to-Scalar Ratio to the Top Quark and Higgs Boson masses

    E-Print Network [OSTI]

    Isabella Masina; Alessio Notari

    2012-05-03T23:59:59.000Z

    For a narrow band of values of the top quark and Higgs boson masses, the Standard Model Higgs potential develops a false minimum at energies of about $10^{16}$ GeV, where primordial Inflation could have started in a cold metastable state. A graceful exit to a radiation-dominated era is provided, e.g., by scalar-tensor gravity models. We pointed out that if Inflation happened in this false minimum, the Higgs boson mass has to be in the range $126.0 \\pm 3.5$ GeV, where ATLAS and CMS subsequently reported excesses of events. Here we show that for these values of the Higgs boson mass, the inflationary gravitational wave background has be discovered with a tensor-to-scalar ratio at hand of future experiments. We suggest that combining cosmological observations with measurements of the top quark and Higgs boson masses represents a further test of the hypothesis that the Standard Model false minimum was the source of Inflation in the Universe.

  15. The top quark to electron mass ratio m(t) = 18*m(e)/alpha^2 where alpha = e^2/hslash*c

    E-Print Network [OSTI]

    Malcolm H. Mac Gregor

    2006-03-24T23:59:59.000Z

    Threshold-state elementary particle lifetimes exhibit a scaling in powers of alpha = e^2/hslash*c, and a reciprocal electron-based 1/alpha scaling in particle masses that extends over two powers of 1/alpha. The m(e)/alpha coupling generates accurate q = (u,d), s, c, b quark masses for particles up to 11 GeV. The m(e)/alpha^2 coupling creates the "alpha-quarks" q^alpha = q/alpha that reproduce the top quark mass and average W^+-, Z^0 doublet mass. The calculated Bc mass is 6303.3 MeV/c^2, and the lattice QCD value is 6304 +- 12 MeV/c^2. The calculated and experimental top quark masses are m(t)calc = 18*m(e)/alpha^2 = 172.73 GeV/c^2 and m(t)exp = 172.5 +- 2.3 GeV/c^2.

  16. Top Mass Measurements at the Tevatron

    E-Print Network [OSTI]

    M. H. L. S. Wang

    2009-04-02T23:59:59.000Z

    We present the latest measurements of the top quark mass from the Tevatron. The different top decay channels and measurement techniques used for these results are also described. The world average of the top quark mass based on some of these new results combined with previous results is mtop=172.6+-1.4 GeV.

  17. Measurement of the top quark mass in $p \\bar{p}$ collisions using events with two leptons

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls; Alverson, George O.; /Northeastern U.; Aoki, Masato; /Fermilab; Askew, Andrew Warren; /Florida State U. /Stockholm U.

    2012-01-01T23:59:59.000Z

    We present a measurement of the top quark mass (m{sub t}) in p{bar p} collisions at {radical}s = 1.96 TeV using t{bar t} events with two leptons (ee, e{mu} or {mu}{mu}) in the final state in 4.3 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider. We analyze the kinematically underconstrained dilepton events by integrating over the neutrino rapidity distributions. We reduce the dominant systematic uncertainties from jet energy calibration using a correction obtained from t{bar t} {yields} {ell} + jets events. We also correct jets in simulated events to replicate the quark flavor dependence of the jet response in data. In combination with our previous analysis, we measure m{sub t} = 174.0 {+-} 2.4(stat) {+-} 1.4(syst) GeV.

  18. Combination of CDF and D0 results on the mass of the top quark using up to 9.7 fb$^{-1}$ at the Tevatron

    E-Print Network [OSTI]

    Tevatron Electroweak Working Group

    2014-07-12T23:59:59.000Z

    We summarize the current top-quark mass measurements from the CDF and D0 experiments at Fermilab. We combine published Run I (1992--1996) results with the most precise published and preliminary Run II (2001--2011) measurements based on data corresponding to up to 9.7 fb$^{-1}$ of $p\\bar{p}$ collisions. Taking correlations of uncertainties into account, and combining the statistical and systematic uncertainties, the resulting preliminary Tevatron average mass of the top quark is $M_{top} = 174.34 \\pm 0.64 ~GeV/c^2$, corresponding to a relative precision of 0.37%.

  19. Top Quark Properties at the TeVatron

    E-Print Network [OSTI]

    Yvonne Peters for the CDF; D0 Collaborations

    2011-03-29T23:59:59.000Z

    Discovered in 1995 by CDF and D0 at the Fermilab Tevatron collider, the top quark remains interesting to test the Standard Model. Having collected more than 7 fb$^{-1}$ of integrated luminosity with both experiments until today, several top quark properties have been measured with increasing precision, while other properties have been investigated for the first time. In this article recent measurements of top quark properties from CDF and D0 are presented, using between 1 fb$^{-1}$ and 4.8 fb$^{-1}$ of data. In particular, the measurement of the top quark mass, the top quark width, the top antitop mass difference, a check of the electric charge of the top quark, measurements of the top antitop quark spin correlation and W helicity as well as a search for charged Higgs bosons are discussed.

  20. Dark decay of Top quark

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kong, Kyoungchui [Kansas; Lee, Hye-Sung [W&M, JLAB; Park, Myeonhun [Tokyo

    2014-04-01T23:59:59.000Z

    We suggest top quark decays as a venue to search for light dark force carriers. Top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6 ? deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t ? b W + Z's. This is the same as the dominant top quark decay (t ? b W) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. We discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.

  1. Top Mass Measurements with the D0 Detector

    E-Print Network [OSTI]

    Daniel Boline

    2015-01-18T23:59:59.000Z

    I present recent results related to the measurement of the top quark mass, using $p\\bar{p}$ collisions recorded with the D{\\O}Detector at the Tevatron. The results are: A direct measurement of the mass difference between top and anti-top quarks, Measurement of the top quark mass in the lepton+jets channel and in the dilepton channel.

  2. The Top Quark Forward Backward Asymmetry at CDF

    E-Print Network [OSTI]

    Yen-Chu Chen for the CDF collaboration

    2011-07-01T23:59:59.000Z

    It has been more than 15 years since the discovery of the top quark. Great strides have been made in the measurement of the top quark mass and the properties of it. Most results show consistency with the standard model. However, using 5 fb$^{-1}$ data, recent measurements of the asymmetry in the production of top and anti-top quark pair have demonstrated surprisingly large values at CDF. Using 4 fb$^{-1}$ data, D0 also has similar effect.

  3. Dark decay of Top quark

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kong, Kyoungchui; Lee, Hye-Sung; Park, Myeonhun

    2014-04-01T23:59:59.000Z

    We suggest top quark decays as a venue to search for light dark force carriers. Top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6 ? deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t ? b W + Z's. This is the same as the dominant topmorequark decay (t ? b W) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. We discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.less

  4. The Top Quark - 2006 and Beyond

    E-Print Network [OSTI]

    John Womersley

    2006-04-04T23:59:59.000Z

    We know there is new physics at the electroweak scale, but we don't know what it is. Right now, the top quark is our only window on to this physics. In almost all models of electroweak symmetry breaking, top either couples strongly to new particles or its properties are modified in some way. Top is being studied in detail at the Fermilab Tevatron. Its production cross section has been measured in a variety of channels; its mass has been determined to better than 2%, and can be used to constrain the mass of the Higgs. Top quark decays have been tested and non-standard production mechanisms searched for. Single top production probes the electroweak properties of top, and has not yet been observed; searches are now closing in on this process and it should be seen soon. So far, all of the top quark's properties are consistent with the Standard Model. However, the data still to come at the Tevatron will increase the precision of all these measurements, and the enormous statistics available at the LHC will open up new possibilities such as observation of spin correlations and perhaps even CP violation in the top sector.

  5. Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

    SciTech Connect (OSTI)

    Aaltonen, T [Helsinki Inst. of Phys.; Alvarez Gonzalez, B [Oviedo U., Cantabria Inst. of Phys.; Amerio, S [INFN, Padua; Amidei, D [Michigan U.; Anastassov, A [Northwestern U.; Annovi, A [Frascati

    2011-10-14T23:59:59.000Z

    A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy ?s = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt? pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb-1 of integrated luminosity, the top-quark mass is measured to be mt = 172.4 1.4 (stat + ?JES) 1.3 (syst) GeV/c2.

  6. Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A

    2011-10-14T23:59:59.000Z

    A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy ?s = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt? pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and amorecorrection to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb-1 of integrated luminosity, the top-quark mass is measured to be mt = 172.4 1.4 (stat + ?JES) 1.3 (syst) GeV/c2.less

  7. Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T [Helsinki Inst. of Phys.; Alvarez Gonzalez, B [Oviedo U., Cantabria Inst. of Phys.; Amerio, S [INFN, Padua; Amidei, D [Michigan U.; Anastassov, A [Northwestern U.; Annovi, A [Frascati

    2011-10-14T23:59:59.000Z

    A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy ?s = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt? pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb-1 of integrated luminosity, the top-quark mass is measured to be mt = 172.4 1.4 (stat + ?JES) 1.3 (syst) GeV/c2.

  8. Top Quark Pair Production in Early CMS Data

    E-Print Network [OSTI]

    Kao, Shih-Chuan

    2011-01-01T23:59:59.000Z

    23 2.13 top decay . . . . . . . . . . . . .of the Top Quark . . . . . . . . . . . . . . . . . . . . .20 Top Production in Hadron

  9. Measurement of the Top Quark Mass by Dynamical Likelihood Method using the Lepton + Jets Events with the Collider Detector at Fermilab

    SciTech Connect (OSTI)

    Kubo, Taichi; /Tsukuba U.

    2008-02-01T23:59:59.000Z

    We have measured the top quark mass with the dynamical likelihood method. The data corresponding to an integrated luminosity of 1.7fb{sup -1} was collected in proton antiproton collisions at a center of mass energy of 1.96 TeV with the CDF detector at Fermilab Tevatron during the period March 2002-March 2007. We select t{bar t} pair production candidates by requiring one high energy lepton and four jets, in which at least one of jets must be tagged as a b-jet. In order to reconstruct the top quark mass, we use the dynamical likelihood method based on maximum likelihood method where a likelihood is defined as the differential cross section multiplied by the transfer function from observed quantities to parton quantities, as a function of the top quark mass and the jet energy scale(JES). With this method, we measure the top quark mass to be 171.6 {+-} 2.0 (stat.+ JES) {+-} 1.3(syst.) = 171.6 {+-} 2.4 GeV/c{sup 2}.

  10. Top Quark: discovery, present and future Galtieri, The Top Quark, PDG 50th

    E-Print Network [OSTI]

    Galtieri, Lina

    1 Top Quark: discovery, present and future Galtieri, The Top Quark, PDG 50th Anniversary. September 23-2006 #12;Chasing the Top Quark 2 Gell-Mann, Zweig uds quarks postulated ('64) GIM mechanism at FNAL 1984 PDG partial listing top should exist Searches at Tristan, PETRA, SPPS, SLC : top not found

  11. Measurement of the top quark mass at CDF using the "neutrino phi weighting" template method on a lepton plus isolated track sample

    E-Print Network [OSTI]

    Choudalakis, Georgios

    We present a measurement of the top quark mass with tt? dilepton events produced in pp? collisions at the Fermilab Tevatron (?s=1.96??TeV) and collected by the CDF II detector. A sample of 328 events with a charged ...

  12. LHC limits on the top-Higgs in models with strong top-quark dynamics

    SciTech Connect (OSTI)

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Ottawa-Carleton Institute for Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States)

    2011-11-01T23:59:59.000Z

    LHC searches for the standard model Higgs boson in WW or ZZ decay modes place strong constraints on the top-Higgs state predicted in many models with new dynamics preferentially affecting top quarks. Such a state couples strongly to top quarks, and is therefore produced through gluon fusion at a rate enhanced relative to the rate for the standard model Higgs boson. A top-Higgs state with mass less than 300 GeV is excluded at 95% C.L. if the associated top-pion has a mass of 150 GeV, and the constraint is even stronger if the mass of the top-pion state exceeds the top-quark mass or if the top-pion decay constant is a substantial fraction of the weak scale. These results have significant implications for theories with strong top dynamics, such as topcolor-assisted technicolor, top-seesaw models, and certain Higgsless models.

  13. Top Quark Production at the LHC

    E-Print Network [OSTI]

    Francesco Span; for the ATLAS; CMS collaborations

    2011-12-16T23:59:59.000Z

    Top quark production in proton proton collisions at the Large Hadron Collider (LHC) is reviewed using data collected by the ATLAS and CMS detectors. Most recent results on searches for new physics related to top quark production mechanism are included.

  14. Top quark physics at the LHC

    E-Print Network [OSTI]

    Werner Bernreuther

    2008-05-09T23:59:59.000Z

    The physics perspectives of the production and decay of single top quarks and top quark pairs at the CERN Large Hadron Collider (LHC) are reviewed from a phenomenological point of view.

  15. Top quark Physics at the Tevatron

    E-Print Network [OSTI]

    Yvonne Peters; for the CDF; D0 Collaborations

    2012-01-06T23:59:59.000Z

    When the heaviest elementary particle known today, the top quark, was discovered in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron collider, a large program to study this particle in details has started. In this article, an overview of the status of top quark physics at the Tevatron is presented. In particular, recent results on top quark production, properties and searches using top quarks are discussed.

  16. Studies of top quark properties at the Tevatron

    SciTech Connect (OSTI)

    Shary, Viatcheslav

    2012-05-01T23:59:59.000Z

    An overview of the recent measurements of the top quark properties in proton antiproton collisions at {radical}s = 1.96 TeV is presented. These measurements are based on 5.4-8.7 fb{sup -1} of data collected with the D0 and CDF experiments at the Fermilab Tevatron collider. The top quark mass and width measurements, studies of the spin correlation in top quark pair production, W boson helicity measurement, searches for anomalous top quark couplings and Lorentz invariance violation are discussed.

  17. The heavy top quark and supersymmetry

    SciTech Connect (OSTI)

    Hall, L.J. [Lawrence Berkeley Lab., CA (United States); [Univ. of California, Berkeley, CA (United States)

    1997-01-01T23:59:59.000Z

    Three aspects of supersymmetric theories are discussed: electroweak symmetry breaking, the issues of flavor, and gauge unification. The heavy top quark plays an important, sometimes dominant, role in each case. Additional symmetries lead to extensions of the Standard Model which can provide an understanding for many of the outstanding problems of particle physics. A broken supersymmetric extension of spacetime allows electroweak symmetry breaking to follow from the dynamics of the heavy top quark; an extension of isospin provides a constrained framework for understanding the pattern of quark and lepton masses; and a grand unified extension of the Standard Model gauge group provides an elegant understanding of the gauge quantum numbers of the components of a generation. Experimental signatures for each of these additional symmetries are discussed.

  18. Top Quark Physics at the Tevatron

    E-Print Network [OSTI]

    Frederic Deliot; Douglas Glenzinski

    2011-10-10T23:59:59.000Z

    We review the field of top-quark physics with an emphasis on experimental techniques. The role of the top quark in the Standard Model of particle physics is summarized and the basic phenomenology of top-quark production and decay is introduced. We discuss how contributions from physics beyond the Standard Model could affect top-quark properties or event samples. The many measurements made at the Fermilab Tevatron, which test the Standard Model predictions or probe for direct evidence of new physics using the top-quark event samples, are reviewed here.

  19. Summary of the session on the top quark

    SciTech Connect (OSTI)

    Butler, Joel N.; /Fermilab

    2011-01-01T23:59:59.000Z

    The CDF and D0 experiments at the Fermilab Tevatron showed recent results on the production and properties of the top quark. The CMS and ATLAS experiments presented first observations of top events at the LHC. Prospects for the top physics at the LHC over the next few years were discussed. CDF and D0 have made remarkable progress in detemerining the properties of the top quark, which so far, conforms to the expectations of the SM. The sophisticated methods they have developed form the basis of the exploration that is now starting at the LHC. New methods, such as the use of boosted top quark signatures, will be necessary to realize fully the potential of the LHC for finding new high mass particles decaying to top and for searching for deviations from the SM. Prospects for the future of top quark physics are very bright.

  20. A Measurement of the Top Quark Mass with the D0 Detector at s**(1/2) = 1.96-TeV using the Matrix Element Method

    SciTech Connect (OSTI)

    Kroeninger, Kevin Alexander; /Bonn U.

    2004-04-01T23:59:59.000Z

    Using a data set of 158 and 169 pb{sup -1} of D0 Run-II data in the electron and muon plus jets channel, respectively, the top quark mass has been measured using the Matrix Element Method. The method and its implementation are described. Its performance is studied in Monte Carlo using ensemble tests and the method is applied to the Moriond 2004 data set.

  1. Measurements of Top Quark Properties at the Tevatron

    SciTech Connect (OSTI)

    Mietlicki, David J.; /Michigan U.

    2012-04-01T23:59:59.000Z

    The top quark is the most recently discovered of the standard model quarks, and studies of its properties are important tests of the standard model. Many measurements of top properties have been produced by the CDF and D0 collaborations, which study top quarks produced in p{bar p} collisions at the Fermilab Tevatron with a center-of-mass energy {radical}s = 1.96 TeV. We describe recent results from top properties measurements at the Tevatron using datasets corresponding to integrated luminosities up to 8.7 fb{sup -1}.

  2. Studies of top quark production at D0

    SciTech Connect (OSTI)

    Gerber, Cecilia E.; /Illinois U., Chicago

    2011-07-01T23:59:59.000Z

    I present recent results on top quark production in pp collisions at a center of mass energy of 1.96 TeV. The studies were performed by the D0 collaboration using approximately 5 fb{sup -1} of data taken during Run II at the Fermilab Tevatron accelerator. The top quark is the heaviest known elementary particle and completes the quark sector of the three-generation structure of the standard model (SM). It differs from the other quarks not only by its much larger mass, but also by its lifetime which is too short to build hadronic bound states. The SM predicts that top quarks are created via two independent production mechanisms at hadron colliders. The primary mode, in which a t{bar t} pair is produced from a gtt vertex via the strong interaction, was used by the D0 and CDF collaborations to establish the existence of the top quark in 1995. The second production mode of top quarks at hadron colliders is the electroweak production of a single top quark from a Wtb vertex. The predicted cross section for single top quark production is about half that of t{bar t} pairs but the signal-to-background ratio is much worse; observation of single top quark production has therefore until recently been impeded by its low rate and difficult background environment compared to the top pair production. In the following sections I will present results for the measurement of the t{bar t} pair and the single top quark production cross section using respectively 5.3 fb{sup -1} and 5.4 fb{sup -1} of data taken by the D0 experiment.

  3. Top quark physics expectations at the LHC

    E-Print Network [OSTI]

    Andrei Gaponenko; for the ATLAS Collaboration; for the CMS Collaboration

    2008-10-22T23:59:59.000Z

    The top quark will be produced copiously at the LHC. This will make both detailed physics studies and the use of top quark decays for detector calibration possible. This talk reviews plans and prospects for top physics activities in the ATLAS and CMS experiments.

  4. Measurement of the top quark mass using template methods on dilepton events in p anti-p collisions at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Taiwan, Inst.

    2006-02-01T23:59:59.000Z

    The authors describe a measurement of the top quark mass from events produced in p{bar p} collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. They identify t{bar t} candidates where both W bosons from the top quarks decay into leptons (e{nu}, {mu}{nu}, or {tau}{nu}) from a data sample of 360 pb{sup -1}. The top quark mass is reconstructed in each event separately by three different methods, which draw upon simulated distributions of the neutrino pseudorapidity, t{bar t} longitudinal momentum, or neutrino azimuthal angle in order to extract probability distributions for the top quark mass. For each method, representative mass distributions, or templates, are constructed from simulated samples of signal and background events, and parameterized to form continuous probability density functions. A likelihood fit incorporating these parameterized templates is then performed on the data sample masses in order to derive a final top quark mass. Combining the three template methods, taking into account correlations in their statistical and systematic uncertainties, results in a top quark mass measurement of 170.1 {+-} 6.0(stat.) {+-} 4.1(syst.) GeV/c{sup 2}.

  5. Single Top Quarks at the Tevatron

    E-Print Network [OSTI]

    A. P. Heinson

    2008-09-05T23:59:59.000Z

    After many years searching for electroweak production of top quarks, the Tevatron collider experiments have now moved from obtaining first evidence for single top quark production to an impressive array of measurements that test the standard model in several directions. This paper describes measurements of the single top quark cross sections, limits set on the CKM matrix element |Vtb|, searches for production of single top quarks produced via flavor-changing neutral currents and from heavy W-prime and H+ boson resonances, and studies of anomalous Wtb couplings. It concludes with projections for future expected significance as the analyzed datasets grow.

  6. Jet substructures of boosted polarized top quarks

    E-Print Network [OSTI]

    Yoshio Kitadono; Hsiang-nan Li

    2014-09-05T23:59:59.000Z

    We study jet substructures of a boosted polarized top quark, which undergoes the semileptonic decay $t\\to b\\ell\

  7. Top Quark Production Asymmetries AFBt and AFBl

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Berger, Edmond L.; Cao, Qing-Hong; Chen, Chuan-Ren; Yu, Jiang-Hao; Zhang, Hao

    2012-02-01T23:59:59.000Z

    A large forward-backward asymmetry is seen in both the top quark rapidity distribution AFBt and in the rapidity distribution of charged leptons AFBl from top quarks produced at the Tevatron. We study the kinematic and dynamic aspects of the relationship of the two observables arising from the spin correlation between the charged lepton and the top quark with different polarization states. We emphasize the value of both measurements, and we conclude that a new physics model which produces more right-handed than left-handed top quarks is favored by the present data.

  8. Top quark physics at the Tevatron

    SciTech Connect (OSTI)

    Antonio Sidoti

    2004-03-17T23:59:59.000Z

    After the successful Run I of the Tevatron (1992-1996),with the top quark discovery, both CDF and D0 experiments were extensively upgraded to meet the challenges of the Tevatron Run II collider. The energy of p{bar p} collisions at the Tevatron was increased from {radical}s = 1.8 TeV to {radical}s = 1.96 TeV. t{bar t} production cross section is expected to increase by a factor of {approx} 30%. Major upgrades in the Tevatron accelerator chain will increase the Run II instantaneous luminosity: the goal is to achieve L = 5 - 20 x 10{sup 31} cm{sup 2}s{sup -1} while the highest luminosity reached up to now (September 2003) is 5.2 x 10{sup 31} cm{sup 2} s{sup -1}. In this paper we will present the top quark properties measured by both CDF and D0 with the first physics-quality data collected during the Run II (March 2002-January 2003). First we will review t{bar t} cross section measurements in the various decay channels; then top quark mass measurements will be presented.

  9. Top Quark Properties in Little Higgs Models

    SciTech Connect (OSTI)

    Berger, C.F.; /SLAC; Perelstein, M.; /Cornell U., CIHEP; Petriello, F.; /Wisconsin U., Madison

    2005-12-08T23:59:59.000Z

    Identifying the mechanism which breaks electroweak symmetry and generates fermion masses is one of the main physics goals for both the LHC and the ILC. Studies of the top quark have the potential to illuminate this issue; since it is the heaviest of the Standard Model (SM) fermions, the top is expected to couple strongly to the symmetry-breaking sector. Consequently, the structure of that sector can have significant, potentially observable effects on the properties of the top. for example, it is well known that the vector and axial t{bar t}Z form factors receive large corrections (of order 5-10%) in certain models of dynamical electroweak symmetry breaking [1]. At future colliders such as the LHC and the ILC, we will be able to pursue a program of precision top physics, similar to the program studying the Z at LEP and SLC. In this manuscript, they study the corrections to the top quark properties in ''Little Higgs'' models of electroweak symmetry breaking [2], and compare the expected deviations from the SM predictions with expected sensitivities of experiments at the LHC and the ILC. In the Little Higgs models, electroweak symmetry is driven by the radiative effects from the top sector, including the SM-like top and its heavy counterpart, a TeV-scale ''heavy top'' T. Probing this structure experimentally is quite difficult. While the LHC should be able to discover the T quark, its potential for studying its couplings is limited [3,4]. Direct production of the T will likely be beyond the kinematic reach of the ILC. However, we will show below that the corrections to the gauge couplings of the SM top, induced by its mixing with the T, will be observable at the ILC throughout the parameter range consistent with naturalness. Measuring these corrections will provide a unique window on the top sector of the Little Higgs. Many Little Higgs models have been proposed in the literature. We will consider two examples in this study, the ''Littlest Higgs'' model [5], and its variation incorporating T parity [6].

  10. Top Quark Forward-Backward Asymmetry

    E-Print Network [OSTI]

    Kingman Cheung; Wai-Yee Keung; Tzu-Chiang Yuan

    2009-11-17T23:59:59.000Z

    The recent forward-backward asymmetry recorded by the CDF Collaboration for the top and anti-top quark pair production indicates more than $2\\sigma$ deviation from the Standard Model prediction, while its total production cross section remains consistent. We propose a $W'$ boson that couples to down and top quarks. We identify the parameter space that can give rise a large enough forward-backward asymmetry without producing too many top and anti-top quark pairs. Other models presented erstwhile in the literature that can produce such effects are also discussed.

  11. THE TOP QUARK Updated December 2011 by T.M. Liss (Univ. Illinois) and A.

    E-Print Network [OSTI]

    1 THE TOP QUARK Updated December 2011 by T.M. Liss (Univ. Illinois) and A. Quadt (Univ. Gottingen). A. Introduction: The top quark is the Q = 2/3, T3 = +1/2 member of the weak-isospin doublet" for more information). This note summarizes the properties of the top quark (mass, production cross section

  12. Observation of $t$-channel electroweak top quark production

    SciTech Connect (OSTI)

    Triplett, Nathan; /Iowa State U.

    2011-04-01T23:59:59.000Z

    The top quark is the heaviest known fundamental particle, with a mass of 172.0{sub -1.3}{sup +0.9}GeV. This is nearly twice the mass of the second heaviest known particle, the Z boson, and roughly the mass of a gold atom. Because of its unusually large mass, studying the top quark may provide insight into the Higgs mechanism and other beyond the standard model physics. Only two accelerators in the world are powerful enough to produce top quarks. The Tevatron, which first accelerated protons in 1983, has produced almost 400,000 top quarks, roughly half at each of its two detectors: DO and CDF. The LHC is a much newer accelerator which currently has accumulated about 0.5% as much data as the Tevatron. However, when running at full luminosity, the LHC is capable of producing a top quark about once every second and will quickly surpass the Tevatron as the leading producer of top quarks. This analysis uses data from the D0 detector at the Tevatron, which are described in chapter 3. Top quarks are produced most often in pairs of top and anti-top quarks through an interaction of the strong force. This production mode was first observed in 1995 at the Tevatron. However, top quarks can also be produced though an electroweak interaction, which produces just one top quark. This production mode was first observed at the Tevatron in 2008. Single top quark production can occur in different channels. In this analysis, a measurement of the cross section of the t-channel production mode is performed. This measurement uses 5.4 fb{sup -1} of data and uses the technique of boosted decision trees in order to separate signal from background events. The t-channel cross section is measured to be: {sigma}(p{bar p} {yields} tqb + X) = 3.03{sub -0.66}{sup +0.78}pb (0.0.1). Additional cross section measurements were also performed for the s-channel as well as the s + t-channel. The measurement of each one of these three cross sections was repeated three times using different techniques, and all three methods were combined into a 'super-method' which achieves the best performance. The details of these additional measurements are shown in appendix A.

  13. Single top quark production at D0

    E-Print Network [OSTI]

    Reinhard Schwienhorst; for the D0 collaboration

    2011-09-13T23:59:59.000Z

    Updates of electroweak single top quark production measurements by the D0 collaboration are presented using 5.4fb^-1 of proton-antiproton collision data from the Tevatron at Fermilab. Measurements of the t-channel, s-channel and combined single top quark production cross section are presented, including an updated lower limit on the CKM matrix element |V_tb|. Also reported are results from searches for gluon-quark flavor-changing neutral currents and W' boson production.

  14. Measurement of the front back asymmetry in top-antitop quark pairs produced in proton-antiproton collisions at center of mass energy = 1.96 TeV

    SciTech Connect (OSTI)

    Schwarz, Thomas A.; /Michigan U.

    2006-01-01T23:59:59.000Z

    Quarks, along with leptons and force carrying particles, are predicted by the Standard Model to be the fundamental constituents of nature. In distinction from the leptons, the quarks interact strongly through the chromodynamic force and are bound together within the hadrons. The familiar proton and neutron are bound states of the light ''up'' and ''down'' quarks. The most massive quark by far, the ''top'' quark, was discovered by the CDF and D0 experiments in March, 1995. The new quark was observed in p{bar p} collisions at 1.8 TeV at the Fermilab Tevatron. The mass of the top quark was measured to be 176 {+-} 13 GeV/c{sup 2} and the cross section 6.8{sub -2.4}{sup +3.6} pb. It is the Q = 2/3, T{sub 3} = +1/2 member of the third generation weak-isospin doublet along with the bottom quark. The top quark is the final Standard Model quark to be discovered. Along with whatever is responsible for electroweak symmetry breaking, top quark physics is considered one of the least understood sectors of the Standard Model and represents a front line of our understanding of particle physics. Currently, the only direct measurements of top quark properties come from the CDF and D0 experiments observing p{bar p} collisions at the Tevatron. Top quark production at the Tevatron is almost exclusively by quark-antiquark annihilation, q{bar q} {yields} t{bar t} (85%), and gluon fusion, gg {yields} t{bar t} (15%), mediated by the strong force. The theoretical cross-section for this process is {sigma}{sub t{bar t}} = 6.7 {+-} 0.8 pb for m{sub t} = 175 GeV/c{sup 2}. Top quarks can also be produced at the Tevatron via q{bar b}{prime} {yields} tb and qg {yields} q{prime}tb through the weak interaction. The cross section for these processes is lower (3pb) and the signal is much more difficult to isolate as backgrounds are much higher. The top quark is predicted to decay almost exclusively into a W-boson and a bottom quark (t {yields} Wb). The total decay width t {yields} Wb is {Lambda} = 1.50 GeV. This corresponds to an incredibly short lifetime of 0.5 x 10{sup -24} seconds. This happens so quickly that hadronization and bound states do not take place, which leads to the interesting consequence that the top quark spin information is passed to the decay products.

  15. Top-quark processes at NLO in production and decay

    SciTech Connect (OSTI)

    Campbell, John M.; Ellis, R.Keith

    2012-04-01T23:59:59.000Z

    We describe the implementation of top production and decay processes in the parton-level Monte Carlo program MCFM. By treating the top quark as being on-shell, we can factorize the amplitudes for top-pair production, s-channel single-top production, and t-channel single-top production into the product of an amplitude for production and an amplitude for decay. In this way we can retain all spin correlations. Both the production and the decay amplitudes are calculated consistently at next-to-leading order in alpha_s. The full dependence on the b-quark mass is also kept. Phenomenological results are presented for various kinematic distributions at the LHC and for the top quark forward-backward asymmetry at the Tevatron.

  16. Top quark physics expectations at the LHC

    E-Print Network [OSTI]

    Gaponenko, Andrei; ATLAS Collaboration; CMS Collaboration

    2008-01-01T23:59:59.000Z

    Physics Analysis Summary TOP 08 005. ATLAS Collaboration,Note 2006/013. E. W. Varnes, Top Physics plenary talk, thismass in the ATLAS cuts based top mass analysis with 1fb ?1

  17. Gluon Radiation in Top Quark Production and Decay at $e^+e^-$ Colliders

    E-Print Network [OSTI]

    Cosmin Macesanu; Lynne H. Orr

    2000-12-18T23:59:59.000Z

    We study gluon radiation in top quark production above threshold at high energy $e^+e^-$ colliders. We allow for the top quarks to be off-shell, considering radiation in both the top production and decay processes simultaneously. Our calculation includes all top width effects, spin correlations, and $b$ quark mass effects. We study the effects of gluon radiation on top mass reconstuction and examine the interference between production- and decay-stage radiation, which can be sensitive to the value of the top quark decay width.

  18. A measurement of the top quark mass in 1.96 TeV proton-antiproton collisions using a novel matrix element method

    SciTech Connect (OSTI)

    Freeman, John C.; /LBL, Berkeley

    2007-12-01T23:59:59.000Z

    A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix elements techniques, the method involves an integration using the Standard Model matrix element for tt production and decay. however, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.

  19. A Measurement of the Top Quark Mass in 1.96 TeV Proton-Antiproton Collisions Using a Novel Matrix Element Method

    SciTech Connect (OSTI)

    CDF Collaboration; Freeman, John; Freeman, John

    2007-09-30T23:59:59.000Z

    A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix element techniques, the method involves an integration using the Standard Model matrix element for t{bar t} production and decay. However, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.

  20. Top Quark Properties from Top Pair Events and Decays

    E-Print Network [OSTI]

    Andrew G. Ivanov; for the CDF; Dzero Collaborations

    2008-10-19T23:59:59.000Z

    Over a decade since the discovery of the top quark we are still trying to unravel mysteries of the heaviest observed particle and learn more about its nature. The continuously accumulating statistics of CDF and Dzero data provide the means for measuring top quark properties with ever greater precision and the opportunity to search for signs of new physics that could be manifested through subtle deviations from the standard model in the production and decays of top quarks. In the following we present a slice of the rich program in top quark physics at the Fermilab Tevatron: measurements of the properties of top quark decays and searches for unusual phenomena in events with pair produced tops. In particular, we discuss the most recent and precise CDF and Dzero measurements of the transverse polarization of W bosons from top decays, branching ratios and searches for flavor-changing neutral current decays, decays into charged Higgs and invisible decays. These analyses correspond to integrated luminosities ranging from 0.9 to 2.7 inv. fb.

  1. Commissioning ATLAS and CMS with top quarks

    E-Print Network [OSTI]

    B. S. Acharya; F. Cavallari; G. Corcella; R. Di Sipio; G. Petrucciani

    2008-05-25T23:59:59.000Z

    The large ttbar production cross-section at the LHC suggests the use of top quark decays to calibrate several critical parts of the detectors, such as the trigger system, the jet energy scale and b-tagging.

  2. Dark Decay of the Top Quark

    SciTech Connect (OSTI)

    Kong, Kyoungchul; Lee, Hye-Sung; Park, Myeonghun

    2014-04-01T23:59:59.000Z

    We suggest top quark decays as a venue to search for light dark force carriers. The top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6sigma deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t-->bW+Z's. This is the same as the dominant top quark decay (t-->bW) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. We discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.

  3. Single top quark production at the Tevatron

    SciTech Connect (OSTI)

    Schwienhorst, Reinhard; /Michigan State U.

    2008-05-01T23:59:59.000Z

    The Tevatron experiments D0 and CDF have found evidence for single top quark production, based on datasets between 0.9 fb{sup -1} and 2.2 fb{sup -1}. Several different multivariate techniques are used to extract the single top quark signal out of the large backgrounds. The cross section measurements are also used to provide the first direct measurement of the CKM matrix element |V{sub tb}|.

  4. Top quark physics in the ATLAS detector: summary of Run I results

    E-Print Network [OSTI]

    Moreno Llacer, Maria; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    An overview of the most recent results on top quark physics obtained using proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider at $\\sqrt{s}$ = 7 TeV or $\\sqrt{s}$ = 8 TeV centre-of-mass energy are presented. Measurements for inclusive and differential top quark pair and single top quark production in different final states are reviewed. The latest measurements of the top quark mass, top quark properties such as charge asymmetry and spin correlations, constraints on the coupling of the top quark to the W boson and the recent evidence of top quark pairs produced in associated with vector bosons are also presented.

  5. Observation of the top quark with the DO detector

    SciTech Connect (OSTI)

    Hadley, N.J. [Univ. of Maryland, College Park, MD (United States)

    1997-01-01T23:59:59.000Z

    The DO Collaboration reports on the observation of the top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. We measure the top quark mass to be 199{sub -21}{sup -19}(stat){sub -21}{sup +14}(syst.) GeV/c{sup 2} and its production cross section to be 6.4 {+-}2.2 pb. Our result is based on approximately 50 pb{sup -1} of data. We observe 17 events with an expected background of 3.8 {+-} 0.6 events. The probability of an upward fluctuation of the background to produce the observed signal is 2 x 10{sup -6} (equivalent to 4.6 standard deviations). The kinematic properties of the events are consistent with top quark decay, and the distribution of events across the seven decay channels is consistent with the Standard Model top quark branching fractions. We describe the analysis that led to the observation of the top quark as well as the properties of the top quark events.

  6. Top quark property measurements at the LHC

    E-Print Network [OSTI]

    Richard Hawkings

    2014-10-29T23:59:59.000Z

    Measurements of top quark properties performed at the Large Hadron Collider are reviewed, with a particular emphasis on top-pair charge asymmetries, spin correlations and polarization measurements performed by the ATLAS and CMS collaborations. The measurements are generally in good agreement with predictions from next-to-leading-order QCD calculations, and no deviations from Standard Model expectations have been seen.

  7. Measurements of the Properties of the Top Quark

    SciTech Connect (OSTI)

    Brandt, Oleg

    2011-08-01T23:59:59.000Z

    We review recent measurements of the properties of the top quark: the decay width of the top quark, of spin correlations between the top and the antitop quarks in t{bar t} production, the W boson helicity in top decays, the strong colour flow in t{bar t} events, and the asymmetry of t{bar t} production due to the strong colour charge. The measurements are performed on data samples of up to 5.4 fb{sup -1} of integrated luminosity acquired by the CDF and D0 collaborations in Run II of the Fermilab Tevatron p{bar p} collider at a centre-of-mass energy of {radical}s = 1.96 TeV.

  8. Measurements of the Top-quark Mass and the $t\\bar{t}$ Cross Section in the Hadronic $\\tau +$ Jets Decay Channel at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-08-01T23:59:59.000Z

    We present the first direct measurement of the top-quark mass using t{bar t} events decaying in the hadronic {tau} + jets decay channel. Using data corresponding to an integrated luminosity of 2.2 fb{sup -1} collected by the CDF II detector in p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron, we measure the t{bar t} cross section, {sigma}{sub t{bar t}}, and the top-quark mass, M{sub top}. We extract M{sub top} from a likelihood based on per-event probabilities calculated with leading-order signal and background matrix elements. We measure {sigma}{sub t{bar t}} = 8.8 {+-} 3.3 (stat) {+-} 2.2 (syst) pb and M{sub top} = 172.7 {+-} 9.3 (stat) {+-} 3.7 (syst) GeV/c{sup 2}.

  9. Evidence for production of single top quarks

    SciTech Connect (OSTI)

    Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Simon Fraser U.; Ahn, S.H.; /Korea U., KODEL; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP /Michigan U.

    2008-03-01T23:59:59.000Z

    We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p{bar p} collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top quark partner that is always produced from strong coupling processes. Top quarks were first observed in pair production in 1995, and since then, single top quark production has been searched for in ever larger datasets. In this analysis, we select events from a 0.9 fb{sup -1} dataset that have an electron or muon and missing transverse energy from the decay of a W boson from the top quark decay, and two, three, or four jets, with one or two of the jets identified as originating from a b hadron decay. The selected events are mostly backgrounds such as W+jets and t{bar t} events, which we separate from the expected signals using three multivariate analysis techniques: boosted decision trees, Bayesian neural networks, and matrix element calculations. A binned likelihood fit of the signal cross section plus background to the data from the combination of the results from the three analysis methods gives a cross section for single top quark production of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.7 {+-} 1.3 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.014%, corresponding to a 3.6 standard deviation significance. The measured cross section value is compatible at the 10% level with the standard model prediction for electroweak top quark production. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa quark mixing matrix element that describes the Wtb coupling and find |V{sub tb}f{sub 1}{sup L}| = 1.31{sub -0.21}{sup +0.25}, where f{sub 1}{sup L} is a generic vector coupling. This model-independent measurement translates into 0.68 < |V{sub tb}| {le} 1 at the 95% C.L. in the standard model.

  10. Uncovering the single top: observation of electroweak top quark production

    SciTech Connect (OSTI)

    Benitez, Jorge Armando; /Michigan State U.

    2009-08-01T23:59:59.000Z

    The top quark is generally produced in quark and anti-quark pairs. However, the Standard Model also predicts the production of only one top quark which is mediated by the electroweak interaction, known as 'Single Top'. Single Top quark production is important because it provides a unique and direct way to measure the CKM matrix element V{sub tb}, and can be used to explore physics possibilities beyond the Standard Model predictions. This dissertation presents the results of the observation of Single Top using 2.3 fb{sup -1} of Data collected with the D0 detector at the Fermilab Tevatron collider. The analysis includes the Single Top muon+jets and electron+jets final states and employs Boosted Decision Tress as a method to separate the signal from the background. The resulting Single Top cross section measurement is: (1) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.74{sub -0.74}{sup +0.95} pb, where the errors include both statistical and systematic uncertainties. The probability to measure a cross section at this value or higher in the absence of signal is p = 1.9 x 10{sup -6}. This corresponds to a standard deviation Gaussian equivalence of 4.6. When combining this result with two other analysis methods, the resulting cross section measurement is: (2) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.94 {+-} 0.88 pb, and the corresponding measurement significance is 5.0 standard deviations.

  11. TOP QUARK PHYSICS AT THE NLC CARL R. SCHMIDT

    E-Print Network [OSTI]

    Schmidt, Carl

    TOP QUARK PHYSICS AT THE NLC CARL R. SCHMIDT Santa Cruz Institute for Particle Physics University) is an excellent tool for studying the properties of the top quark. In this talk I review some of the theory of top, is an ideal tool for studying the properties of the top quark. The event environment in e + e \\Gamma

  12. Top quark mass measurement in the tt[over -bar] all hadronic channel using a matrix element technique in pp[over -bar] collisions at sqrt[s]=1.96 TeV

    E-Print Network [OSTI]

    Xie, Si

    We present a measurement of the top quark mass in the all hadronic channel (tt??bb?q[subscript 1]q?[subscript 2]q[subscript 3]q?[subscript 4] using 943??pb[superscript -1] of pp? collisions at ?s=1.96??TeV collected at the ...

  13. Determination of the top-quark pole mass and strong coupling constant from the t[bar over t] production cross section in pp collisions at ?s = 7 TeV

    E-Print Network [OSTI]

    Apyan, Aram

    The inclusive cross section for top-quark pair production measured by the CMS experiment in protonproton collisions at a center-of-mass energy of 7 TeV is compared to the QCD prediction at next-to-next-to-leading order ...

  14. Top quark measurement in the CDF

    E-Print Network [OSTI]

    Hyun Su Lee; for the CDF Collaboration

    2009-05-28T23:59:59.000Z

    We present recent top physics results in the CDF including updates of top mass, \\ttbar cross section, single top search, forward-backward asymmetry, and the differential cross section of \\ttbar. Most of measurements utilize close to the integrated luminosity of 3 fb$^{-1}$.

  15. Measurement of the top quark mass with the dynamical likelihood method using lepton plus jets events with b-tags in p anti-p collisions at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Taiwan,

    2005-12-01T23:59:59.000Z

    This report describes a measurement of the top quark mass, M{sub top}, with the dynamical likelihood method (DLM) using the CDF II detector at the Fermilab Tevatron. The Tevatron produces top/anti-top (t{bar t}) pairs in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The data sample used in this analysis was accumulated from March 2002 through August 2004, which corresponds to an integrated luminosity of 318 pb{sup -1}. They use the t{bar t} candidates in the ''lepton+jets'' decay channel, requiring at least one jet identified as a b quark by finding an displaced secondary vertex. The DLM defines a likelihood for each event based on the differential cross section as a function of M{sub top} per unit phase space volume of the final partons, multiplied by the transfer functions from jet to parton energies. The method takes into account all possible jet combinations in an event, and the likelihood is multiplied event by event to derive the top quark mass by the maximum likelihood method. Using 63 t{bar t} candidates observed in the data, with 9.2 events expected from background, they measure the top quark mass to be 173.2{sub -2.4}{sup +2.6}(stat.) {+-} 3.2(syst.) GeV/c{sup 2}, or 173.2{sub -4.0}{sup +4.1} GeV/c{sup 2}.

  16. The Top Mass: Interpretation and Theoretical Uncertainties

    E-Print Network [OSTI]

    Andr H. Hoang

    2014-12-11T23:59:59.000Z

    Currently the most precise LHC measurements of the top quark mass are determinations of the top quark mass parameter of Monte-Carlo (MC) event generators reaching uncertainties of well below $1$ GeV. However, there is an additional theoretical problem when using the MC top mass $m_t^{\\rm MC}$ as an input for theoretical predictions, because a rigorous relation of $m_t^{\\rm MC}$ to a renormalized field theory mass is, at the very strict level, absent. In this talk I show how - nevertheless - some concrete statements on $m_t^{\\rm MC}$ can be deduced assuming that the MC generator behaves like a rigorous first principles QCD calculator for the observables that are used for the analyses. I give simple conceptual arguments showing that in this context $m_t^{\\rm MC}$ can be interpreted like the mass of a heavy-light top meson, and that there is a conversion relation to field theory top quark masses that requires a non-perturbative input. The situation is in analogy to B physics where a similar relation exists between experimental B meson masses and field theory bottom masses. The relation gives a prescription how to use $m_t^{\\rm MC}$ as an input for theoretical predictions in perturbative QCD. The outcome is that at this time an additional uncertainty of about $1$ GeV has to be accounted for. I discuss limitations of the arguments I give and possible ways to test them, or even to improve the current situation.

  17. Top Quark Results Using CMS Data at 7 TeV

    E-Print Network [OSTI]

    Karl M. Ecklund; for the CMS Collaboration

    2011-10-10T23:59:59.000Z

    I give an overview of recent results on top quark properties and interactions, obtained using data collected with the CMS experiment during the years 2010--2011 at sqrt(s)= 7 TeV. Measurements are presented for the inclusive top pair production cross section, using the dilepton, lepton plus jets, and hadronic channels. The mass of the top quark is measured using the dilepton and lepton plus jets samples. CMS also measures the cross section for electroweak production of single top quarks and constrains the CKM matrix element V_tb. Top quark results are compared with Standard Model predictions and used to search for possible presence of new physics. In particular, measurements of the top-pair invariant mass distribution are used to search for new particles decaying to top pairs. CMS has also investigated the top-pair charge asymmetry to search for possible new physics contributions.

  18. Search for rare top-quark decays at the LHC

    E-Print Network [OSTI]

    Veloso, Filipe; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    Flavour-changing neutral-current (FCNC) top quark decays are suppressed by the GIM mechanism, but are enhanced by BSM models. Any evidence for top-quark FCNC decays could be an evidence for new physics. Searches for the FCNC decays $t\\to qX$ where $X=Z,\\gamma,H,g$ and $q=u,c$ performed by the ATLAS and CMS Collaborations are presented. Data collected during 2011 and 2012 from proton-proton ($pp$) collisions at the LHC at a centre-of-mass energy of $\\sqrt{s}=7$ and 8 TeV, corresponding to integrated luminosities ranging from 2.1 fb$^{-1}$ to 25 fb$^{-1}$, are analysed. Top-quark pair-production events with one top quark decaying through the $t\\to qZ,q\\gamma,qH$ channels and the other through the dominant Standard Model mode $t\\to bW$ are considered as signal, as well as direct top production for the $t\\to qg$ channel. No evidence for FCNC signals are found and upper limits on the $t\\to qX$ branching ratios are set at 95\\% confidence level.

  19. Improving the Top Quark Forward-Backward Asymmetry Measurement at the LHC

    SciTech Connect (OSTI)

    Bai, Yang; /SLAC; Han, Zhenyu; /Harvard U., Phys. Dept.

    2011-08-15T23:59:59.000Z

    At the LHC, top quark pairs are dominantly produced from gluons, making it difficult to measure the top quark forward-backward asymmetry. To improve the asymmetry measurement, we study variables that can distinguish between top quarks produced from quarks and those from gluons: the invariant mass of the top pair, the rapidity of the top-antitop system in the lab frame, the rapidity of the top quark in the top-antitop rest frame, the top quark polarization and the top-antitop spin correlation. We combine all the variables in a likelihood discriminant method to separate quark-initiated events from gluon-initiated events. We apply our method on models including G-prime's and W-prime's motivated by the recent observation of a large top quark forward-backward asymmetry at the Tevatron. We have found that the significance of the asymmetry measurement can be improved by 10% to 30%. At the same time, the central values of the asymmetry increase by 40% to 100%. We have also analytically derived the best spin quantization axes for studying top quark polarization as well as spin-correlation for the new physics models.

  20. Top Quark Physics: Future Measurements R. Frey, D. Gerdes, J. Jaros, S. Vejcik, E. Berger, R. S. Chivukula, F. Cuypers, P. Drell,

    E-Print Network [OSTI]

    Frey, Raymond E.

    Top Quark Physics: Future Measurements R. Frey, D. Gerdes, J. Jaros, S. Vejcik, E. Berger, R. S discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize mea­ surements of the top quark's mass

  1. Higgs Bosons from Top Quark Decays

    E-Print Network [OSTI]

    Tao Han; Richard Ruiz

    2014-04-28T23:59:59.000Z

    In light of the discovery of a Standard Model (SM)-like Higgs boson ($h$) at the LHC, we investigate the top quark to Higgs boson transition $t\\rightarrow W^{*}bh$, which is the leading $t\\to h$ decay mode in the SM. We find the decay branching fraction to be $1.80\\times 10^{-9}$. In comparison, the two-body, loop-induced $t\\rightarrow ch$ transition occurs at $\\sim10^{-14}$ in the SM. We consider the consequences of gauge invariant dimension-6 operators affecting the $t\\bar{t}h$ interaction and find that the decay branching fraction may be increased by a factor of two within current constraints on the coupling parameters from collider experiments. We also extend the calculation to the CP-conserving Type I and Type II Two Higgs Doublet Models (2HDM), including both CP-even and CP-odd Higgs bosons. For neutral scalar masses at about $100$ GeV, the decay rates can be several times larger than the SM result in the allowed range of model parameters. Observation prospects at present and future colliders are briefly addressed.

  2. Top quark physics at the Tevatron

    SciTech Connect (OSTI)

    Bhat, P.C.

    1998-04-01T23:59:59.000Z

    The authors review the analyses of t{bar t} candidate events in various decay channels, carried out using the p{bar p} collider data at {radical}s = 1.8 TeV by the CDF and D0 collaborations at the Fermilab Tevatron. The measurements of the top quark mass (m{sub t}) using lepton+jets channel yield m{sub t} = 173.3 {+-} 7.8 GeV/c{sup 2} from D0 analysis and m{sub t} = 175.9 {+-} 6.9 GeV/c{sup 2} from CDF analysis. The production cross section is measured to be {sigma}{sub t{bar t}} = 7.6{sub -1.5}{sup +1.8} pb by CDF and {sigma}{sub t{bar t}} = 5.6 {+-} 1.8 pb by D0. Further investigations using t{bar t} decays and future prospects are briefly discussed.

  3. Determination of the width of the top quark

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Abolins, Maris A.; /Michigan State U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls; Alverson, George O.; /Northeastern U.; Alves, Gilvan Augusto; /Rio de Janeiro, CBPF /Nijmegen U.

    2010-09-01T23:59:59.000Z

    We extract the total width of the top quark, {Lambda}{sub t}, from the partial decay width {Lambda}(t {yields} Wb) measured using the t-channel cross section for single top quark production and from the branching fraction B(t {yields} Wb) measured in t{bar t} events using up to 2.3 fb{sup -1} of integrated luminosity collected by the D0 Collaboration at the Tevatron p{bar p} Collider. The result is {Lambda}{sub t} = 1.99{sub -0.55}{sup +0.69} GeV, which translates to a top-quark lifetime of {tau}{sub t} = (3.3{sub -0.9}{sup +1.3}) x 10{sup -25} s. Assuming a high mass fourth generation b{prime} quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |V{sub tb{prime}}| < 0.63 at 95% C.L.

  4. Determination of the top-quark pole mass and strong coupling constant from the t t-bar production cross section in pp collisions at sqrt(s) = 7 TeV

    E-Print Network [OSTI]

    CMS Collaboration

    2014-08-20T23:59:59.000Z

    The inclusive cross section for top-quark pair production measured by the CMS experiment in proton-proton collisions at a center-of-mass energy of 7 TeV is compared to the QCD prediction at next-to-next-to-leading order with various parton distribution functions to determine the top-quark pole mass, mtpole, or the strong coupling constant, alphaS. With the parton distribution function set NNPDF2.3, a pole mass of 176.7 +3.0 -2.8 GeV is obtained when constraining alphaS at the scale of the Z boson mass, mZ, to the current world average. Alternatively, by constraining mtpole to the latest average from direct mass measurements, a value of alphaS(mZ) = 0.1151 +0.0028 -0.0027 is extracted. This is the first determination of alphaS using events from top-quark production.

  5. Top quark and electroweak results from CDF

    SciTech Connect (OSTI)

    Sandra Leone

    2003-11-04T23:59:59.000Z

    In 2001 the Tevatron run II began, after a five year period of significant upgrade of the accelerator itself and of the experiments CDF and D0. After a detector commissioning run, the CDF experiment is now taking high quality data with all subsystems functional. We report in this talk the first preliminary CDF results on top quark and W/Z boson properties, based on run II data. The top quark, discovered in 1995 at the Tevatron, has proven to be a very interesting particle. Its properties allow to perform stringent tests of the Standard Model (SM) and to search for new physics through a deviation from SM predictions. We give here some expectations of what Tevatron run II will ultimately provide to our understanding of matter.

  6. Top Quark Production Cross Section at the Tevatron

    SciTech Connect (OSTI)

    Shabalina, E.; /Chicago U.

    2006-05-01T23:59:59.000Z

    An overview of the preliminary results of the top quark pair production cross section measurements at a center-of-mass energy of 1.96 TeV carried out by the CDF and D0 collaborations is presented. The data samples used for the analyses are collected in the current Tevatron run and correspond to an integrated luminosity from 360 pb{sup -1} up to 760 pb{sup -1}.

  7. Search of anomalous $Wtb$ couplins in single top quark prodution at D0

    SciTech Connect (OSTI)

    Joshi, Jyoti; Beri, Suman; /Panjab U.

    2011-12-01T23:59:59.000Z

    The large mass of the top quark, close to the electroweak symmetry-breaking scale, makes it a good candidate for probing physics beyond the Standard Model, including possible anomalous couplings. D0 has made measurements of single top quark production using 5.4 fb{sup -1} of integrated luminosity. We examine the data to study the Lorentz structure of the Wtb coupling. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. In 2009, the electroweak single top quark production was observed by the D0 and CDF collaborations. Electroweak production of top quarks at the Tevatron proceeds mainly via the decay of a time-like virtual W boson accompanied by a bottom quark in the s-channel (tb = t{bar b} + {bar t}b), or via the exchange of a space-like virtual W boson between a light quark and a bottom quark in the t-channel (tqb = tq{bar b} + {bar t}qb, where q refers to the light quark). For a top quark mass of 172.5 GeV, The Standard Model (SM) prediction of single top production rate at next-to-leading order with soft-gluon contributions at next-to-next-to-leading order are 1.04 {+-} 0.04 pb (s-channel) and 2.26 {+-} 0.12 pb (t-channel). The large mass of the top quark implies that it has large couplings to the electroweak symmetry breaking sector of the SM and may have non-standard interactions with the weak gauge bosons. Single top quark production provides a unique probe to study the interactions of the top quark with the W boson.

  8. Top properties in $t\\bar{t}$ events at CMS (includes mass)

    E-Print Network [OSTI]

    V. Adler; on behalf of the CMS Collaboration

    2013-02-12T23:59:59.000Z

    Selected results from the following topics are presented: Measurements of several top quark properties are obtained from the CMS data collected in 2011 at a center-of-mass energy of 7 TeV. The results include measurements of the top quark mass, the W helicity in top decays, the top quark charge, and of the $t\\bar{t}$ spin correlation and the search for anomalous couplings.

  9. Single top quark production and Vtb at the Tevatron

    SciTech Connect (OSTI)

    Schwienhorst, Reinhard; /Michigan State U.

    2010-09-01T23:59:59.000Z

    Single top quark production via the electroweak interaction was observed by the D0 and CDF collaborations at the Tevatron proton-antiproton collider at Fermilab. Multivariate analysis techniques are employed to extract the small single top quark signal. The combined Tevatron cross section is 2.76{sub -0.47}{sup +0.58} pb. This corresponds to a lower limit on the CKM matrix element |V{sub tb}| of 0.77. Also reported are measurements of the t-channel cross section, the top quark polarization in single top quark events, and limits on gluon-quark flavor-changing neutral currents and W{prime} boson production.

  10. Search for electroweak single top quark production with CDF

    SciTech Connect (OSTI)

    Kemp, Y.; /Karlsruhe U.

    2005-01-01T23:59:59.000Z

    We report on a search for Standard Model t-channel and s-channel single top quark production in p{bar p} collisions at a center of mass energy of 1.96 TeV. We use a data sample corresponding to 162 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. We find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section, consistent with the Standard Model: 10.1 pb for the t-channel, 13.6 pb for the s-channel and 17.8 pb for the combined cross section of t- and s-channel.

  11. arbitrary quark mass: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with small uncertainty allows us to predict properties of the as-yet-unobserved Higgs boson. This paper presents the status of the measurements of the top quark mass. A. P....

  12. Observation of Single Top Quark Production

    SciTech Connect (OSTI)

    Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Alberta U. /Simon Fraser U. /York U., Canada /McGill U.; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan State U. /Northeastern U.

    2009-03-01T23:59:59.000Z

    We report first observation of the electroweak production of single top quarks in p{bar p} collisions at {radical}s = 1.96 TeV based on 2.3 fb{sup ?1} of data collected by the D0 detector at the Fermilab Tevatron Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of b quarks, we measure a cross section of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.94 {+-} 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10{sup ?7}, corresponding to a 5.0 standard deviation significance for the observation.

  13. CDF/PUB/TOP/PUBLIC/10793 Measurement of Single Top Quark Production

    E-Print Network [OSTI]

    Quigg, Chris

    CDF/PUB/TOP/PUBLIC/10793 Measurement of Single Top Quark Production in 7.5 fb-1 of CDF Data Using a measurement of single top quark production in lepton plus jets final state using 7.5 fb-1 of p¯p collision a bottom quark. We use the new POWHEG Monte Carlo generator for single top signal samples in s-channel, t

  14. Dynamical electroweak symmetry breaking and the top quark

    SciTech Connect (OSTI)

    Chivukula, R.S. [Boston Univ., MA (United States)

    1997-01-01T23:59:59.000Z

    In this talk, I discuss theories of dynamical electroweak symmetry breaking, with emphasis on the implications of a heavy top quark on the weak interaction {rho} parameter.

  15. Search for charged Higgs bosons in top quark decays

    E-Print Network [OSTI]

    Baringer, Philip S.; Bean, Alice; Clutter, Justace Randall; Moulik, Tania; Wilson, Graham Wallace; DØ Collaboration; Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Aguilo, E.; Ahsan, M.

    2009-12-07T23:59:59.000Z

    We present a search for charged Higgs bosons in top quark decays. We analyze the e+jetse+jets, ?+jets?+jets, ee, e?, ??, ?e and ?? final states from top quark pair production events, using data from about 1 fb^(?1) of integrated luminosity recorded...

  16. Top quark spin correlations and polarization at the LHC: standard model predictions and effects of anomalous top chromo moments

    E-Print Network [OSTI]

    Werner Bernreuther; Zong-Guo Si

    2015-03-16T23:59:59.000Z

    A number of top-spin observables are computed within the Standard Model (SM), at next-to-leading order in the strong and weak gauge couplings for hadronic top-quark anti-quark (ttbar) production and decay at the LHC for center-of-mass energies 7 and 8 TeV. For dileptonic final states we consider the azimuthal angle correlation, the helicity correlation, and the opening angle distribution; for lepton plus jets final states we determine distributions and asymmetries that trace a longitudinal and transverse polarization, respectively, of the t and t-bar samples. In addition, we investigate the effects of a non-zero chromo-magnetic and chromo-electric dipole moment of the top quark on these and other top-spin observables and associated asymmetries. These observables allow to disentangle the contributions from the real and imaginary parts of these moments.

  17. Top Quark Production and Decay at Nexttoleading Order in e + e \\Gamma Annihilation

    E-Print Network [OSTI]

    Schmidt, Carl

    found a mass of 199 +19 \\Gamma21 \\Sigma 22 GeV, while CDF obtained a mass of 176 \\Sigma 8 \\Sigma 10 GeV. Both of these mass measurements are in excellent agreement with the value of 175 \\Sigma 11 +17 \\Gamma19. The top quark is certainly unique among the six known quarks. It is by far the heaviest; more than 30

  18. Quark Number Susceptibility with Finite Quark Mass in Holographic QCD

    E-Print Network [OSTI]

    Kyung-il Kim; Youngman Kim; Shingo Takeuchi; Takuya Tsukioka

    2011-10-31T23:59:59.000Z

    We study the effect of a finite quark mass on the quark number susceptibility in the framework of holographic QCD. We work in a bottom-up model with a deformed AdS black hole and D3/D7 model to calculate the quark number susceptibility at finite temperature with/without a finite quark chemical potential. As expected the finite quark mass suppresses the quark number susceptibility. We find that at high temperatures $T\\ge 600$ MeV the quark number susceptibility of light quarks and heavy quarks are almost equal in the bottom-up model. This indicates that the heavy quark like charm contribution to thermodynamics of a QCD-like system may start to become significant at temperatures $T\\sim 600$ MeV. In D3/D7 model, we focus on the competition between the quark chemical potential, which enhances the quark number susceptibility, and the quark mass that suppresses the susceptibility. We observe that depending on the relative values of the quark mass and the quark chemical potential, the quark number susceptibility shows a diverging or converging behavior. We also calculate the chiral susceptibility in D3/D7 model to support the observation made with the quark number susceptibility.

  19. Search for Single Top Quark Production at LEP2

    E-Print Network [OSTI]

    The OPAL collaboration; G. Abbiendi

    2001-10-04T23:59:59.000Z

    A search for single top quark production via flavour changing neutral currents (FCNC) was performed with data collected by the OPAL detector at the e+e- collider LEP. Approximately 600 pb-1 of data collected at sqrt(s) = 189 - 209 GeV were used to search for the FCNC process e+ e- -> tc(u) -> bWc(u). This analysis is sensitive to the leptonic and the hadronic decay modes of the W boson. No evidence for a FCNC process is observed. Upper limits at the 95% confidence level on the single top production cross-section as a function of the centre-of-mass energy are derived. Limits on the anomalous coupling parameters kappa_gamma and kappa_Z are determined from these results.

  20. Energy profile of b-jet for boosted top quarks

    E-Print Network [OSTI]

    Yoshio Kitadono

    2014-09-05T23:59:59.000Z

    We analyse the semileptonic decay of a polarised top-quark with a large velocity based on the perturbative QCD factorisation framework. Thanks to the factorisation and the spin decomposition, the production part and the decay part can be factorised and the spin dependence is introduced in the decay part. The decay part is converted to the top-jet function which describes the distribution of jet observables and the spin is translated to the helicity of the boosted top. Using this top-jet function, the energy profile of b-jet is investigated and it is turned out that the sub-jet energy for the helicity-minus top is accumulated faster than that for the helicity-plus top. This behaviour for the boosted top can be understood with the negative spin-analysing-power of b-quark in the polarised-top decay.

  1. Tracking down hyper-boosted top quarks

    E-Print Network [OSTI]

    Larkoski, Andrew J; Selvaggi, Michele

    2015-01-01T23:59:59.000Z

    The identification of hadronically decaying heavy states, such as vector bosons, the Higgs, or the top quark, produced with large transverse boosts has been and will continue to be a central focus of the jet physics program at the Large Hadron Collider (LHC). At a future hadron collider working at an order-of-magnitude larger energy than the LHC, these heavy states would be easily produced with transverse boosts of several TeV. At these energies, their decay products will be separated by angular scales comparable to individual calorimeter cells, making the current jet substructure identification techniques for hadronic decay modes not directly employable. In addition, at the high energy and luminosity projected at a future hadron collider, there will be numerous sources for contamination including initial- and final-state radiation, underlying event, or pile-up which must be mitigated. We propose a simple strategy to tag such "hyper-boosted" objects that defines jets with radii that scale inversely proportion...

  2. First observation of top quark production in the forward region

    E-Print Network [OSTI]

    Aaij, Roel; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; d'Argent, Philippe; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Bel, Lennaert; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bertolin, Alessandro; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Birnkraut, Alex; Bizzeti, Andrea; Blake, Thomas; Blanc, Frdric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Braun, Svende; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Capriotti, Lorenzo; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carniti, Paolo; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cavallero, Giovanni; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Dlage, Nicolas; Demmer, Moritz; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Di Ruscio, Francesco; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Surez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dufour, Laurent; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Frber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferrari, Fabio; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fohl, Klaus; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; Garca Pardias, Julin; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gastaldi, Ugo; Gauld, Rhorry; Gavardi, Laura; Gazzoni, Giulio; Geraci, Angelo; Gerick, David; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gian, Sebastiana; Gibson, Valerie; Girard, Olivier Gran; Giubega, Lavinia-Helena; Gligorov, Vladimir; Gbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gndara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto

    2015-01-01T23:59:59.000Z

    Top quark production in the forward region in proton-proton collisions is observed for the first time. The $W\\!+\\!b$ final state with $W\\to\\mu\

  3. A New Top Mass Measurement in The Dilepton Channel

    SciTech Connect (OSTI)

    Trovato, Marco; /INFN, Pisa /Pisa U.

    2008-01-01T23:59:59.000Z

    The top quark discovery completed the present picture of the fundamental constituents of the nature. Since then, the Collider Detector at Fermilab and D0 Collaborations have been spending great efforts to measure its properties better. About 30 times larger than the second heaviest quark, the mass of the top has been measured with increased statistic and more and more sophisticated techniques in order to reduce as much as possible its uncertainty. This is because the top is expected to play a fundamental role in the Standard Model. The value of its mass sets boundaries on the mass of the unobserved Higgs boson, and perhaps more appealing, studies of its properties might lead to the discovery of new physics.

  4. Quark masses: An environmental impact statement

    E-Print Network [OSTI]

    Kimchi, Itamar

    We investigate worlds that lie on a slice through the parameter space of the standard model over which quark masses vary. We allow as many as three quarks to participate in nuclei, while fixing the mass of the electron and ...

  5. Angular correlations in top quark decays in standard model extensions

    SciTech Connect (OSTI)

    Batebi, S. [Science and Research Branch, Islamic Azad University (IAU), Tehran (Iran, Islamic Republic of); Etesami, S. M. [School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Physics Department, Isfahan University of Technology (IUT), P.O. Box 11365-9161, Isfahan (Iran, Islamic Republic of); Mohammadi-Najafabadi, M. [Physics Department, Isfahan University of Technology (IUT), P.O. Box 11365-9161, Isfahan (Iran, Islamic Republic of)

    2011-03-01T23:59:59.000Z

    The CMS Collaboration at the CERN LHC has searched for the t-channel single top quark production using the spin correlation of the t-channel. The signal extraction and cross section measurement rely on the angular distribution of the charged lepton in the top quark decays, the angle between the charged lepton momentum and top spin in the top rest frame. The behavior of the angular distribution is a distinct slope for the t-channel single top (signal) while it is flat for the backgrounds. In this Brief Report, we investigate the contributions which this spin correlation may receive from a two-Higgs doublet model, a top-color assisted technicolor (TC2) and the noncommutative extension of the standard model.

  6. Search for New Physics with Top and Bottom Quarks with ATLAS

    SciTech Connect (OSTI)

    Khanov, Alexander

    2013-12-11T23:59:59.000Z

    The studies performed by the principal investigator during the period of the grant constitute the ground work for search for new physics in channels including top and bottom quarks with the ATLAS detector at the Large Hadron Collider. The PI has been involved in search for heavy charged Higgs bosons decaying into top and bottom quark pairs, and top quark rare decays involving Higgs bosons and c-quarks. Both channels have the top quark pair production as their main background, which was studied in detail. The search for heavy charged Higgs and top quark rare decays requires signi#12;cant amount of data accumulated by the experiment. In case no signal is observed in the present data sample collected by ATLAS (5 fb{sup -1} of integrated luminosity at proton-anti proton center-of-mass energy of 7 TeV and 20 fb{sup -1} at 8 TeV), data from the upgraded detector running at 14 TeV needs to be analyzed. The PI has been working on physics and performance studies at upgraded detector.

  7. Lina Galtieri: Top Mass Measurements. Aspen2010, January 17-23 1 Precision Top Mass Measurement

    E-Print Network [OSTI]

    Galtieri, Lina

    Lina Galtieri: Top Mass Measurements. Aspen2010, January 17-23 1 Precision Top Mass Measurement Measurements. Aspen2010, January 17-23 2 Motivation Mw~ Mt 2 Mw~ log(MH) Quantum loop the combination of many EWK observable #12;Lina Galtieri: Top Mass Measurements. Aspen2010, January 17-23 3 Top

  8. Top-Quark Initiated Processes at High-Energy Hadron Colliders

    E-Print Network [OSTI]

    Tao Han; Joshua Sayre; Susanne Westhoff

    2014-11-10T23:59:59.000Z

    In hadronic collisions at high energies, the top-quark may be treated as a parton inside a hadron. Top-quark initiated processes become increasingly important since the top-quark luminosity can reach a few percent of the bottom-quark luminosity. In the production of a heavy particle $H$ with mass $m_H > m_t$, treating the top-quark as a parton allows us to resum large logarithms $\\log(m_{H}^{2}/m_{t}^{2}$) arising from collinear splitting in the initial state. We quantify the effect of collinear resummation at the 14-TeV LHC and a future 100-TeV hadron collider, focusing on the top-quark open-flavor process $gg\\to t\\bar t H$ in comparison with $t\\bar t \\to H$ and $tg\\rightarrow tH$ at the leading order (LO) in QCD. We employ top-quark parton distribution functions with appropriate collinear subtraction and power counting. We find that (1) Collinear resummation enhances the inclusive production of a heavy particle with $m_H\\approx$ 5 TeV (0.5 TeV) by more than a factor of two compared to the open-flavor process at a 100-TeV (14-TeV) collider; (2) Top-quark mass effects are important for scales $m_H$ near the top-quark threshold, where the cross section is largest. We advocate a modification of the ACOT factorization scheme, dubbed m-ACOT, to consistently treat heavy-quark masses in hadronic collisions; (3) The scale uncertainty of the total cross section in m-ACOT is of about 20 percent at the LO. While a higher-order calculation is indispensable for a precise prediction, the LO cross section is well described by the process $t\\bar t\\to H$ using an effective factorization scale significantly lower than $m_H$. We illustrate our results by the example of a heavy spin-0 particle. Our main results also apply to the production of particles with spin-1 and 2.

  9. Top quark induced effective potential in a composite Higgs model

    E-Print Network [OSTI]

    Maarten Golterman; Yigal Shamir

    2015-05-13T23:59:59.000Z

    We consider non-perturbative aspects of a composite Higgs model that serves as a prototype for physics beyond the Standard Model, in which a new strongly interacting sector undergoes chiral symmetry breaking, and generates the Higgs particle as a pseudo Nambu-Goldstone boson. In addition, the top quark couples linearly to baryons of the new strong sector, thereby becoming partially composite. We study the dynamics leading to the top quark Yukawa coupling as well as the top quark contribution to the effective potential for the Higgs, obtaining expressions for these couplings in terms of baryonic correlation functions in the underlying strongly interacting theory. We then show that a large-N limit exists in which the top quark contribution to the Higgs effective potential overcomes that of the weak gauge bosons, inducing electroweak symmetry breaking. The same large-N limit also suggests that the baryons that couple to the top quark may be relatively light. This composite Higgs model, and similar ones, can be studied on the lattice with the methods developed for lattice QCD.

  10. Measurement of leptonic asymmetries and top-quark polarization in tt-bar production

    E-Print Network [OSTI]

    Baringer, Philip S.; Bean, Alice; Chen, G.; Clutter, Justace Randall; Sekaric, Jadranka; Wilson, Graham Wallace; Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Askew, A.; Atkins, S.

    2013-01-24T23:59:59.000Z

    We present measurements of lepton (?) angular distributions in top-quark (t) pair production and tt-bar?W+bW?b-bar??+?b???-b-ar b-bar decays produced in pp-bar collisions at a center-of-mass energy of s?=1.96??TeV, where ...

  11. Top quark electric and chromo electric dipole moments in the general two Higgs Doublet model

    E-Print Network [OSTI]

    E. O. Iltan

    2002-02-11T23:59:59.000Z

    We study the electric and chromo electric dipole moment of top quark in the general two Higgs Doublet model (model III). We analyse the dependency of this quantity to the new phases coming from the complex Yukawa couplings and masses of charged and neutral Higgs bosons. We observe that the electric and chromo elecric dipole moments of top quark are at the order of 10^{-21} e cm and 10^{-20} g_s cm, which are extremely large values compared to ones calculated in the SM and also two Higgs Doublet model with real Yukawa couplings.

  12. Production of two Z-bosons in gluon fusion in the heavy top quark approximation

    E-Print Network [OSTI]

    Melnikov, Kirill

    2015-01-01T23:59:59.000Z

    We compute QCD radiative corrections to the continuum production of a pair of Z-bosons in the annihilation of two gluons. We only consider the contribution of the top quark loops and we treat them assuming that $m_t$ is much larger than any other kinematic invariant in the problem. We estimate the QCD corrections to $pp \\to ZZ$ using the first non-trivial term in the expansion in the inverse top quark mass and we compare them to QCD corrections of the signal process, $pp \\to H \\to ZZ$.

  13. Reconstructing top quark-antiquark events with one lost jet

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Demina, Regina [Univ. of Rochester, Rochester, NY (United States); Harel, Amnon [Univ. of Rochester, Rochester, NY (United States); Orbaker, Douglas [Univ. of Rochester, Rochester, NY (United States)

    2015-07-01T23:59:59.000Z

    We present a technique for reconstructing the kinematics of pair-produced top quarks that decay to a charged lepton, a neutrino and four final state quarks in the subset of events where only three jets are reconstructed. We present a figure of merit that allows for a fair comparison of reconstruction algorithms without requiring their calibration. The new reconstruction of events with only three jets is fully competitive with the full reconstruction typically used for four-jet events.

  14. The latest results on top quark pair cross-section measurement

    E-Print Network [OSTI]

    Yamauchi, Katsuya; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    The latest results on top quark pair production cross-section measurement in proton-proton collisions at $\\sqrt{s} = 7\\ TeV$ and $\\sqrt{s} = 8\\ TeV$ with the ATLAS detector are reported. The inclusive cross-section was measured with 4% of uncertainty using di-lepton e-mu events. The measurement of the differential cross-section as functions of various observables such as transverse momentum and rapidity of the top quark and invariant mass of the pseudo-top-quark pair system including the results in boosted topologies are also reported. These results are compared with the various generators such as Powheg, Alpgen and MC@NLO and the various PDF sets.

  15. Measurement of the Single Top Quark Cross Section in the Lepton Plus Jets Final State in Proton-Antiproton Collisions at a Center of Mass Energy of 1.96 TeV Using the CDF II Detector

    SciTech Connect (OSTI)

    Wu, Zhenbin

    2012-01-01T23:59:59.000Z

    We present a measurement of the single top quark cross section in the lepton plus jets final state using an integrated luminosity corresponding to 7.5~\\text{fb}^{-1} of p\\bar p collision data collected by the Collider Detector at Fermilab. The single top candidate events are identified by the signature of a charged lepton, large missing transverse energy, and two or three jets with at least one of them identified as originating from a bottom quark. A new Monte Carlo generator \\textsc{powheg} is used to model the single top quark production processes, which include {s}-channel, {t}-channel, and {Wt}-channel. A neural network multivariate method is exploited to discriminate the single top quark signal from the comparatively large backgrounds. We measure a single top production cross section of $3.04^{+0.57}_{-0.53}$ (\\mathrm{stat.~+~syst.}) pb assuming $m_{\\rm top}=172.5$~GeV/$c^2$. In addition, we extract the CKM matrix element value $|V_{tb}|=0.96\\pm 0.09~(\\mathrm{stat.~+~syst.})\\pm 0.05~(\\mathrm{theory})$ and set a lower limit of |V_{tb}|>0.78 at the 95\\% credibility level.

  16. Top-quark transverse-momentum distributions in t-channel single-top production

    E-Print Network [OSTI]

    Nikolaos Kidonakis

    2013-06-15T23:59:59.000Z

    I present approximate next-to-next-to-leading-order (NNLO) top-quark transverse momentum, pT, distributions in t-channel single-top production. These distributions are derived from next-to-next-to-leading-logarithm (NNLL) soft-gluon resummation. Theoretical results for the single top as well as the single antitop pT distributions are shown for LHC and Tevatron energies.

  17. Jet Multiplicity in Top-Quark Pair Events at CMS

    E-Print Network [OSTI]

    A. Descroix for the CMS Collaboration

    2014-11-11T23:59:59.000Z

    The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity. Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the ttbar production is determined as a function of the additional jet multiplicity. The fraction of events with no additional jets is measured as a function of the threshold required for the transverse momentum of the additional jet. The measurements are compared with predictions from perturbative quantum chromodynamics and no significant deviations are observed.

  18. Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in p p Collisions at s = 8 TeV Using the ATLAS Detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O.?S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B.?S.; Adamczyk, L.; Adams, D.?L.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J.?A.; Agustoni, M.; Ahlen, S.?P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; kesson, T.?P.?A.; Akimoto, G.; Akimov, A.?V.; Alberghi, G.?L.; Albert, J.; Albrand, S.; Alconada Verzini, M.?J.; Aleksa, M.; Aleksandrov, I.?N.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B.?M.?M.; Allison, L.?J.; Allport, P.?P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; Alviggi, M.?G.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S.?P.; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L.?S.; Andari, N.; Andeen, T.; Anders, C.?F.; Anders, G.; Anderson, K.?J.; Andreazza, A.; Andrei, V.; Anduaga, X.?S.; Angelidakis, S.; Angelozzi, I.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A.?V.; Anjos, N.; Annovi, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J.?P.; Arce, A.?T.?H.; Arduh, F.?A.; Arguin, J-F.; Argyropoulos, S.; Arik, M.; Armbruster, A.?J.; Arnaez, O.; Arnal, V.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ashkenazi, A.; sman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N.?B.; Auerbach, B.; Augsten, K.; Aurousseau, M.; Avolio, G.; Axen, B.; Azuelos, G.; Azuma, Y.; Baak, M.?A.; Baas, A.?E.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Badescu, E.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J.?T.; Baker, O.?K.; Balek, P.; Balli, F.; Banas, E.; Banerjee, Sw.; Bannoura, A.?A.?E.; Bansil, H.?S.; Barak, L.; Baranov, S.?P.; Barberio, E.?L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnes, S.?L.; Barnett, B.?M.; Barnett, R.?M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A.?J.; Barreiro, F.; Barreiro Guimares da Costa, J.; Bartoldus, R.; Barton, A.?E.; Bartos, P.; Bartsch, V.; Bassalat, A.; Basye, A.; Bates, R.?L.; Batista, S.?J.; Batley, J.?R.; Battaglia, M.; Battistin, M.; Bauer, F.; Bawa, H.?S.; Beacham, J.?B.; Beattie, M.?D.; Beau, T.; Beauchemin, P.?H.; Beccherle, R.; Bechtle, P.; Beck, H.?P.; Becker, K.; Becker, S.; Beckingham, M.; Becot, C.; Beddall, A.?J.; Beddall, A.; Bedikian, S.; Bednyakov, V.?A.; Bee, C.?P.; Beemster, L.?J.; Beermann, T.?A.; Begel, M.; Behr, K.; Belanger-Champagne, C.; Bell, P.?J.; Bell, W.?H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J.?A.; Benjamin, D.?P.; Bensinger, J.?R.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Beringer, J.; Bernard, C.; Bernard, N.?R.; Bernius, C.; Bernlochner, F.?U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertsche, C.; Bertsche, D.; Besana, M.?I.; Besjes, G.?J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethke, S.; Bevan, A.?J.; Bhimji, W.; Bianchi, R.?M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S.?P.; Bierwagen, K.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Black, C.?W.; Black, J.?E.; Black, K.?M.; Blackburn, D.; Blair, R.?E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G.?J.; Bobrovnikov, V.?S.; Bocchetta, S.?S.; Bocci, A.; Bock, C.; Boddy, C.?R.; Boehler, M.; Boek, T.?T.; Bogaerts, J.?A.; Bogdanchikov, A.?G.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A.?S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E.?V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I.?R.; Bozic, I.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J.?E.; Braun, H.?M.; Brazzale, S.?F.; Brelier, B.; Brendlinger, K.; Brennan, A.?J.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T.?M.; Britton, D.; Brochu, F.?M.; Brock, I.; Brock, R.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W.?K.; Brosamer, J.; Brost, E.

    2015-04-01T23:59:59.000Z

    A measurement of spin correlation in tt production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb?. The correlation between the top and antitop quark spins is extracted from dilepton tt events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.380.04, in agreement with the standard model prediction. A search is performed for pair production of top squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.

  19. Recent results in the top quark sector from the D0 experiment

    E-Print Network [OSTI]

    Brandt, Oleg

    2015-01-01T23:59:59.000Z

    In these proceedings, I review recent measurements in the top quark sector in $p\\bar p$ collisions at a centre-of-mass energy of $\\sqrt s=1.96$ TeV in Run II of the Fermilab Tevatron Collider using the D0 detector. I will present the differential measurement of the $t\\bar t$ production cross section and the Tevatron combination of inclusive $t\\bar t$ cross section measurements; the first evidence of the production of single top quarks in the $s$-channel by D0 and the observation in combination with CDF. Furthermore, I will review the measurements of the forward-backward asymmetry in $t\\bar t$ events, and conclude with the world's most precise single measurement of the top quark mass, which is a fundamental parameter of the standard model, and present the Tevatron combination, which is the world's most precise determination of the top quark mass, with a relative precision of 0.37\\%.

  20. Search for pair production of the scalar top quark in the electron+muon final state

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Altona, A.; Alverson, G.; Alves, G.A.

    2010-09-01T23:59:59.000Z

    We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ({tilde t}{sub 1}) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb{sup -1}. The scalar top quarks are assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}), and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and improved exclusion limits at the 95% C.L. are set in the (M{sub {tilde t}{sub 1}}, M{sub {tilde {nu}}}) mass plane.

  1. Top quarks at the Tevatron: Measurements of the top quark production and decay with the D0 experiment

    SciTech Connect (OSTI)

    Strandberg, Jonas; /Stockholm U.

    2006-04-01T23:59:59.000Z

    This thesis presents two measurements of the to pquark using 230 pb{sup -1} of data recorded with the D0 detector at the Tevatron accelerator. The first measurement determines the top pair production cross section at {radical}s = 1.96 TeV in proton-antiproton collisions. In the standard model of particle physics the top quark decays almost exclusively into a W boson and a b quark. Candidate events are selected by requiring that at least one jet in the event is tagged with the secondary vertex algorithm.

  2. Quark Masses: An Environmental Impact Statement

    E-Print Network [OSTI]

    Robert L. Jaffe; Alejandro Jenkins; Itamar Kimchi

    2009-04-03T23:59:59.000Z

    We investigate worlds that lie on a slice through the parameter space of the Standard Model over which quark masses vary. We allow as many as three quarks to participate in nuclei, while fixing the mass of the electron and the average mass of the lightest baryon flavor multiplet. We classify as "congenial" worlds that satisfy the environmental constraint that the quark masses allow for stable nuclei with charges one, six, and eight, making organic chemistry possible. Whether a congenial world actually produces observers depends on a multitude of historical contingencies, beginning with primordial nucleosynthesis, which we do not explore. Such constraints may be independently superimposed on our results. Environmental constraints such as the ones we study may be combined with information about the a priori distribution of quark masses over the landscape of possible universes to determine whether the measured values of the quark masses are determined environmentally, but our analysis is independent of such an anthropic approach. We estimate baryon masses as functions of quark masses and nuclear masses as functions of baryon masses. We check for the stability of nuclei against fission, strong particle emission, and weak nucleon emission. For two light quarks with charges 2/3 and -1/3, we find a band of congeniality roughly 29 MeV wide in their mass difference. We also find another, less robust region of congeniality with one light, charge -1/3 quark, and two heavier, approximately degenerate charge -1/3 and 2/3 quarks. No other assignment of light quark charges yields congenial worlds with two baryons participating in nuclei. We identify and discuss the region in quark-mass space where nuclei would be made from three or more baryon species.

  3. Observation of Electroweak Single Top-Quark Production

    E-Print Network [OSTI]

    Xie, Si

    We report the observation of single top-quark production using 3.2??fb[superscript -1] of pp? collision data with ?s=1.96??TeV collected by the Collider Detector at Fermilab. The significance of the observed data is 5.0 ...

  4. Direct Top-Quark Width Measurement at CDF

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present a measurement of the top-quark width in the lepton+jets decay channel of tt? events produced in pp? collisions at Fermilabs Tevatron collider and collected by the CDF II detector. From a data sample corresponding ...

  5. Search for the top quark at CDF

    SciTech Connect (OSTI)

    Shaw, N.M. [Purdue Univ., Lafayette, IN (United States). Dept. of Physics; The CDF Collaboration

    1992-11-01T23:59:59.000Z

    We review prospects for top discovery in the current 1992 CDF run, focusing on the inclusive electron and muon channels. In the standard model, {approximately} 37% of t{bar t} events contain a high P{sub T} electron or muon. In particular, B tagging through soft leptons and secondary vertices are discussed. Expected signal to background and prospects for the current CDF 1992 run are given.

  6. Direct Measurement of the Total Decay Width of the Top Quark

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present a measurement of the total decay width of the top quark using events with top-antitop quark pair candidates reconstructed in the final state with one charged lepton and four or more hadronic jets. We use the ...

  7. Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in p p Collisions at s = 8 TeV Using the ATLAS Detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O.?S.; Abramowicz, H.; et al

    2015-04-01T23:59:59.000Z

    A measurement of spin correlation in tt production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb?. The correlation between the top and antitop quark spins is extracted from dilepton tt events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.380.04, in agreement with the standard model prediction. A search is performed for pair production of topmoresquarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.less

  8. Light quark masses using domain wall fermions

    E-Print Network [OSTI]

    Tom Blum; Amarjit Soni; Matthew Wingate

    1998-09-10T23:59:59.000Z

    We compute the one-loop self-energy correction to the massive domain wall quark propagator. Combining this calculation with simulations at several gauge couplings, we estimate the strange quark mass in the continuum limit. The perturbative one-loop mass renormalization is comparable to that for Wilson quarks and considerably smaller than that for Kogut-Susskind quarks. Also, scaling violations appear mild in comparison to other errors at present. Given their good chiral behavior and these features, domain wall quarks are attractive for evaluating the light quark masses. Our preliminary quenched result is m_s(2 GeV) = 82(15) MeV in the ${\\bar{MS}}$ scheme.

  9. Tevatron top physics

    E-Print Network [OSTI]

    Jeannine Wagner-Kuhr; for the CDF; D0 Collaborations

    2009-04-15T23:59:59.000Z

    A summary of the most recent results on top quark physics obtained at Fermilab's Tevatron proton-antiproton collider, operating at a centre of mass energy of 1.96 TeV, is presented. Measurements of the top pair and single top quark production cross sections, the investigation of top quark decay properties, the precision measurement of the top quark mass as well as searches for physics beyond the standard model are discussed.

  10. Measurement of Top-Quark Polarization in t-channel Single-Top Production

    E-Print Network [OSTI]

    Matthias Komm; for the CMS Collaboration

    2014-11-29T23:59:59.000Z

    The measurement of the top quark polarization, sensitive to the electroweak coupling structure, in t-channel single-top production is presented. Events are analyzed corresponding to an integrated luminosity of approximately $20~\\mathrm{fb^{-1}}$ recorded with the CMS detector during pp collisions at $\\sqrt{s}=8~\\mathrm{TeV}$. By requiring one isolated lepton (muon or electron), two jets, and missing transverse energy, an angular asymmetry, sensitive to the polarization of the top quark, is reconstructed in the top-quark rest frame. The corresponding angular asymmetry at parton level is inferred from data in a phase space with enhanced single-top t-channel candidates through unfolding. Remaining background contributions are estimated through a ML-fit and subtracted. A polarization of $P_{t}=0.82\\pm0.12\\mathrm{~(stat.)}\\pm0.32\\mathrm{~(syst.)}$ is measured assuming a spin-analyzing power of the charged lepton stemming from the top decay of $100\\%$.

  11. Study of the top quark electric charge at the CDF experiment

    SciTech Connect (OSTI)

    Bartos, Pavol; /Comenius U.

    2011-09-01T23:59:59.000Z

    We report on the measurement of the top quark electric charge using the jet charge tagging method on events containing a single lepton collected by the CDF II detector at Fermilab between February 2002 and February 2010 at the center-of-mass energy {radical}s = 1.96 TeV. There are three main components to this measurement: determining the charge of the W (using the charge of the lepton), pairing the W with the b-jet to ensure that they are from the same top decay branch and finally determining the charge of the b-jet using the Jet Charge algorithm. We found, on a sample of 5.6 fb{sup -1} of data, that the p-value under the standard model hypothesis is equal to 13.4%, while the p-value under the exotic model hypothesis is equal to 0.014%. Using the a priori criteria generally accepted by the CDF collaboration, we can say that the result is consistent with the standard model, while we exclude an exotic quark hypothesis with 95% confidence. Using the Bayesian approach, we obtain for the Bayes factor (2ln(BF)) a value of 19.6, that favors very strongly the SM hypothesis over the XM one. The presented method has the highest sensitivity to the top quark electric charge among the presented so far top quark charge analysis.

  12. Forward-backward asymmetry in top quark-antiquark production

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U.; Augustana Coll., Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Aoki, Masato [Fermilab; Louisiana Tech. U.

    2011-12-12T23:59:59.000Z

    We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb-1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.

  13. Forward-backward asymmetry in top quark-antiquark production

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Alverson, George O; Alves, Gilvan Augusto; et al

    2011-12-12T23:59:59.000Z

    We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb-1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 4.0)%.moreThe results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.less

  14. Forward-backward asymmetry in top quark-antiquark production

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U.; Augustana Coll., Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Aoki, Masato [Fermilab; Louisiana Tech. U.

    2011-12-12T23:59:59.000Z

    We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb-1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.

  15. Search for scalar top and bottom quarks at the Tevatron

    SciTech Connect (OSTI)

    Calfayan, Philippe; /Munich U.

    2009-01-01T23:59:59.000Z

    This document reviews recent results on the search for scalar top and scalar bottom quarks in p{bar p} collisions at {radical}s = 1.96 TeV. The analyses presented are based on data samples with integrated luminosities from 1.0 to 1.9 fb{sup -1} recorded at the Tevatron with the D0 and CDF detectors.

  16. Top quark pair production cross section at the Tevatron

    SciTech Connect (OSTI)

    Cortiana, Giorgio; /INFN, Padua /Padua U.

    2008-04-01T23:59:59.000Z

    Top quark pair production cross section has been measured at the Tevatron by CDF and D0 collaborations using different channels and methods, in order to test standard model predictions, and to search for new physics hints affecting the t{bar t} production mechanism or decay. Measurements are carried out with an integrated luminosity of 1.0 to 2.0 fb{sup -1}, and are found to be consistent with standard model expectations.

  17. Mass inequality for the quark propagator

    E-Print Network [OSTI]

    Dean Lee; Richard Thomson

    2005-06-09T23:59:59.000Z

    We show that for any gauge-fixing scheme with positive semi-definite functional integral measure, the inverse correlation length of the quark propagator is bounded below by one-half the pion mass.

  18. Running heavy-quark masses in DIS

    E-Print Network [OSTI]

    S. Alekhin; S. -O. Moch

    2011-07-03T23:59:59.000Z

    We report on determinations of the running mass for charm quarks from deep-inelastic scattering reactions. The method provides complementary information on this fundamental parameter from hadronic processes with space-like kinematics. The obtained values are consistent with but systematically lower than the world average as published by the PDG. We also address the consequences of the running mass scheme for heavy-quark parton distributions in global fits to deep-inelastic scattering data.

  19. Tevatron Top Results

    E-Print Network [OSTI]

    Christophe Clement

    2006-05-28T23:59:59.000Z

    I present the latest results from the CDF and D0 collaborations on top quark production (single top and top quark pair production) at the Tevatron proton-antiproton collider at sqrt(s) =1.96 TeV, measurements of the top quark decay properties such as the branching ratio B(t -> Wb), the W helicity in t -> Wb decays, and measurements of fundamental parameters such as the top quark charge and mass.

  20. Collider Detector at Fermilab (CDF): Data from the Top Group's Top Quark Research

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The Collider Detector at Fermilab (CDF) is a Tevatron experiment at Fermilab. The Tevatron, a powerful particle accelerator, accelerates protons and antiprotons close to the speed of light, and then makes them collide head-on inside the CDF detector. The CDF detector is used to study the products of such collisions. The CDF Physics Group at Fermilab is organized into six working groups, each with a specific focus. The Top group studies the properties of the top quark, the heaviest known fundamental particle. Their public web page makes data and numerous figures available from both CDF Runs I and II.

  1. Evidence for single top quark production using Bayesian neural networks

    SciTech Connect (OSTI)

    Kau, Daekwang; /Florida State U.

    2007-08-01T23:59:59.000Z

    We present results of a search for single top quark production in p{bar p} collisions using a dataset of approximately 1 fb{sup -1} collected with the D0 detector. This analysis considers the muon+jets and electron+jets final states and makes use of Bayesian neural networks to separate the expected signals from backgrounds. The observed excess is associated with a p-value of 0.081%, assuming the background-only hypothesis, which corresponds to an excess over background of 3.2 standard deviations for a Gaussian density. The p-value computed using the SM signal cross section of 2.9 pb is 1.6%, corresponding to an expected significance of 2.2 standard deviations. Assuming the observed excess is due to single top production, we measure a single top quark production cross section of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.4 {+-} 1.5 pb.

  2. Search for Scalar Top Quark Production in $p\\bar{p}$ Collisions at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-03-01T23:59:59.000Z

    We report on a search for the supersymmetric partner of the top quark (scalar top) decaying into a charm quark and a neutralino in p{bar p} collisions at {radical}s = 1.96 TeV. The data sample, collected by the CDF II detector at the Fermilab Tevatron, corresponds to an integrated luminosity of 2.6 fb{sup -1}. Candidate events are selected by requiring two or more jets and a large imbalance in the transverse momentum. To enhance the analysis sensitivity, at least one of the jets is required to be identified as originating from a charm quark using an algorithm specifically designed for this analysis. The selected events are in good agreement with standard model predictions. In the case of large mass splitting between the scalar top quark and the neutralino we exclude a scalar top quark mass below 180 GeV/c{sup 2} at 95% confidence level.

  3. The Top Quark, Its Discovery, and Subsequent Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening a solidSynthesis of 2Dand WaterTheManagementTheThe Top Quark, Its

  4. Search for W-prime boson production in the top quark decay channel

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Agelou, M.; Agram, J.-L.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; /Buenos Aires U. /Rio de

    2006-07-01T23:59:59.000Z

    We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W bosons at the 95% confidence level for several different W' boson masses. We exclude masses below 610 GeV for a W' boson with standard-model-like couplings, below 630 GeV for a W' boson with right-handed couplings that is allowed to decay to both leptons and quarks, and below 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.

  5. Calculation of associated production of a top quark and a W ? at the LHC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cao, Qing-Hong; Berger, Edmond L.; Yu, Jiang-Hao; Yuan, C.-P.

    2011-11-01T23:59:59.000Z

    We investigate collider signatures of a top-philic W' model, in which the W' boson couples only to the third-generation quarks of the standard model. The main discovery channel for this W' is through associated production of the W' and top quark, yielding a top-quark pair plus an extra bottom-quark jet as a signal. We do a full simulation of the signal and relevant backgrounds. We develop a method of analysis that allows us to conclude that discovery of the W' is promising at the LHC despite large standard model backgrounds. Bottom-quark tagging of the extra jet is key to suppressing the backgrounds.

  6. Exotic Physics with the Top Quark at the LHC. End of grant report

    SciTech Connect (OSTI)

    Black, Kevin

    2013-07-29T23:59:59.000Z

    The grant supported two main activities : searching for new physics with the top quark at the LHC and development of the ATLAS muon trigger.

  7. Search for Resonances Decaying to Top and Bottom Quarks with the CDF Experiment

    E-Print Network [OSTI]

    CDF Collaboration; T. Aaltonen; S. Amerio; D. Amidei; A. Anastassov; A. Annovi; J. Antos; F. Anza'; G. Apollinari; J. A. Appel; T. Arisawa; A. Artikov; J. Asaadi; W. Ashmanskas; B. Auerbach; A. Aurisano; F. Azfar; W. Badgett; T. Bae; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; P. Barria; P. Bartos; M. Bauce; F. Bedeschi; S. Behari; G. Bellettini; J. Bellinger; D. Benjamin; A. Beretvas; A. Bhatti; L. Bianchi; K. R. Bland; B. Blumenfeld; A. Bocci; A. Bodek; D. Bortoletto; J. Boudreau; A. Boveia; L. Brigliadori; C. Bromberg; E. Brucken; J. Budagov; H. S. Budd; K. Burkett; G. Busetto; P. Bussey; P. Butti; A. Buzatu; A. Calamba; S. Camarda; M. Campanelli; F. Canelli; B. Carls; D. Carlsmith; R. Carosi; S. Carrillo; B. Casal; M. Casarsa; A. Castro; P. Catastini; D. Cauz; V. Cavaliere; A. Cerri; L. Cerrito; Y. C. Chen; M. Chertok; G. Chiarelli; G. Chlachidze; K. Cho; D. Chokheli; A. Clark; C. Clarke; M. E. Convery; J. Conway; M. Corbo; M. Cordelli; C. A. Cox; D. J. Cox; M. Cremonesi; D. Cruz; J. Cuevas; R. Culbertson; N. d'Ascenzo; M. Datta; P. de Barbaro; L. Demortier; L. Marchese; M. Deninno; F. Devoto; M. D'Errico; A. Di Canto; B. Di Ruzza; J. R. Dittmann; M. D'Onofrio; S. Donati; M. Dorigo; A. Driutti; K. Ebina; R. Edgar; A. Elagin; R. Erbacher; S. Errede; B. Esham; S. Farrington; J. P. Fernndez Ramos; R. Field; G. Flanagan; R. Forrest; M. Franklin; J. C. Freeman; H. Frisch; Y. Funakoshi; C. Galloni; A. F. Garfinkel; P. Garosi; H. Gerberich; E. Gerchtein; S. Giagu; V. Giakoumopoulou; K. Gibson; C. M. Ginsburg; N. Giokaris; P. Giromini; V. Glagolev; D. Glenzinski; M. Gold; D. Goldin; A. Golossanov; G. Gomez; G. Gomez-Ceballos; M. Goncharov; O. Gonzlez Lpez; I. Gorelov; A. T. Goshaw; K. Goulianos; E. Gramellini; C. Grosso-Pilcher; R. C. Group; J. Guimaraes da Costa; S. R. Hahn; J. Y. Han; F. Happacher; K. Hara; M. Hare; R. F. Harr; T. Harrington-Taber; K. Hatakeyama; C. Hays; J. Heinrich; M. Herndon; A. Hocker; Z. Hong; W. Hopkins; S. Hou; R. E. Hughes; U. Husemann; M. Hussein; J. Huston; G. Introzzi; M. Iori; A. Ivanov; E. James; D. Jang; B. Jayatilaka; E. J. Jeon; S. Jindariani; M. Jones; K. K. Joo; S. Y. Jun; T. R. Junk; M. Kambeitz; T. Kamon; P. E. Karchin; A. Kasmi; Y. Kato; W. Ketchum; J. Keung; B. Kilminster; D. H. Kim; H. S. Kim; J. E. Kim; M. J. Kim; S. B. Kim; S. H. Kim; Y. K. Kim; Y. J. Kim; N. Kimura; M. Kirby; K. Knoepfel; K. Kondo; D. J. Kong; J. Konigsberg; A. V. Kotwal; M. Kreps; J. Kroll; M. Kruse; T. Kuhr; M. Kurata; A. T. Laasanen; S. Lammel; M. Lancaster; K. Lannon; G. Latino; H. S. Lee; J. S. Lee; S. Leo; S. Leone; J. D. Lewis; A. Limosani; E. Lipeles; A. Lister; H. Liu; Q. Liu; T. Liu; S. Lockwitz; A. Loginov; A. Luc; D. Lucchesi; J. Lueck; P. Lujan; P. Lukens; G. Lungu; J. Lys; R. Lysak; R. Madrak; P. Maestro; S. Malik; G. Manca; A. Manousakis-Katsikakis; F. Margaroli; P. Marino; K. Matera; M. E. Mattson; A. Mazzacane; P. Mazzanti; R. McNulty; A. Mehta; P. Mehtala; C. Mesropian; T. Miao; D. Mietlicki; A. Mitra; H. Miyake; S. Moed; N. Moggi; C. S. Moon; R. Moore; M. J. Morello; A. Mukherjee; Th. Muller; P. Murat; M. Mussini; J. Nachtman; Y. Nagai; J. Naganoma; I. Nakano; A. Napier; J. Nett; C. Neu; T. Nigmanov; L. Nodulman; S. Y. Noh; O. Norniella; L. Oakes; S. H. Oh; Y. D. Oh; I. Oksuzian; T. Okusawa; R. Orava; L. Ortolan; C. Pagliarone; E. Palencia; P. Palni; V. Papadimitriou; W. Parker; G. Pauletta; M. Paulini; C. Paus; T. J. Phillips; G. Piacentino; E. Pianori; J. Pilot; K. Pitts; C. Plager; L. Pondrom; S. Poprocki; K. Potamianos; F. Prokoshin; A. Pranko; F. Ptohos; G. Punzi; I. Redondo Fernndez; P. Renton; M. Rescigno; F. Rimondi; L. Ristori; A. Robson; T. Rodriguez; S. Rolli; M. Ronzani; R. Roser; J. L. Rosner; F. Ruffini; A. Ruiz; J. Russ; V. Rusu; W. K. Sakumoto; Y. Sakurai; L. Santi; K. Sato; V. Saveliev; A. Savoy-Navarro; P. Schlabach; E. E. Schmidt; T. Schwarz; L. Scodellaro; F. Scuri; S. Seidel; Y. Seiya; A. Semenov; F. Sforza; S. Z. Shalhout; T. Shears; P. F. Shepard; M. Shimojima; M. Shochet; I. Shreyber-Tecker; A. Simonenko; K. Sliwa; J. R. Smith; F. D. Snider; V. Sorin; H. Song; M. Stancari; R. St. Denis; D. Stentz; J. Strologas; Y. Sudo; A. Sukhanov; I. Suslov; K. Takemasa; Y. Takeuchi; J. Tang; M. Tecchio; P. K. Teng; J. Thom; E. Thomson; V. Thukral; D. Toback; S. Tokar; K. Tollefson; T. Tomura; D. Tonelli; S. Torre; D. Torretta; P. Totaro; M. Trovato; F. Ukegawa; S. Uozumi; F. Vzquez; G. Velev; C. Vellidis; C. Vernieri; M. Vidal; R. Vilar; J. Vizn; M. Vogel; G. Volpi; P. Wagner; R. Wallny; S. M. Wang; D. Waters; W. C. Wester III; D. Whiteson; A. B. Wicklund; S. Wilbur; H. H. Williams; J. S. Wilson; P. Wilson; B. L. Winer; P. Wittich; S. Wolbers; H. Wolfe; T. Wright; X. Wu; Z. Wu; K. Yamamoto; D. Yamato; T. Yang; U. K. Yang; Y. C. Yang; W. -M. Yao; G. P. Yeh; K. Yi; J. Yoh; K. Yorita; T. Yoshida; G. B. Yu; I. Yu; A. M. Zanetti; Y. Zeng; C. Zhou; S. Zucchelli

    2015-04-07T23:59:59.000Z

    We report on a search for charged massive resonances decaying to top ($t$) and bottom ($b$) quarks in the full data set of proton-antiproton collisions at center-of-mass energy of $\\sqrt{s} = 1.96$ TeV collected by the CDF~II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 $fb^{-1}$. No significant excess above the standard model (SM) background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged particle production cross section times branching ratio to $t b$. Using a SM extension with a $W^{\\prime}$ and left-right-symmetric couplings as a benchmark model, we constrain the $W^{\\prime}$ mass and couplings in the 300 to 900 GeV/$c^2$ range. The limits presented here are the most stringent for a charged resonance with mass in the range 300 -- 600 GeV/$c^2$ decaying to top and bottom quarks.

  8. Lattice QCD Thermodynamics with Physical Quark Masses

    E-Print Network [OSTI]

    R. A. Soltz; C. DeTar; F. Karsch; Swagato Mukherjee; P. Vranas

    2015-02-08T23:59:59.000Z

    Over the past few years new physics methods and algorithms as well as the latest supercomputers have enabled the study of the QCD thermodynamic phase transition using lattice gauge theory numerical simulations with unprecedented control over systematic errors. This is largely a consequence of the ability to perform continuum extrapolations with physical quark masses. Here we review recent progress in lattice QCD thermodynamics, focussing mainly on results that benefit from the use of physical quark masses: the crossover temperature, the equation of state, and fluctuations of the quark number susceptibilities. In addition, we place a special emphasis on calculations that are directly relevant to the study of relativistic heavy ion collisions at RHIC and the LHC.

  9. ATLAS results on top properties

    E-Print Network [OSTI]

    F. Derue

    2014-08-26T23:59:59.000Z

    Recent measurements of top quark properties using $t{\\bar t}$ events produced in proton-proton collisions at the Large Hadron Collider with centre of mass energies of 7 and 8 TeV and detected by the ATLAS experiment are presented. These results include top quark mass, the top and anti-top mass difference, the electric charge, the top quark polarization and spin correlation, the $t{\\bar t}$ charge asymmetry and the search for flavour changing neutral currents.

  10. Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events at the Tevatron

    SciTech Connect (OSTI)

    Johnson, William Casey; /UC, Davis

    2010-05-01T23:59:59.000Z

    We search for pair production of the supersymmetric partner of the top quark, the stop quark {tilde t}{sub 1}, decaying to a b-quark and a chargino {tilde {chi}}{sub 1}{sup {+-}} with a subsequent decay into a neutralino {tilde {chi}}{sub 1}{sup 0}, lepton {ell}, and neutrino {nu}. Using 2.7 fb{sup -1} of {radical}s = 1.96 TeV p{bar p} collision data collected by the CDF II experiment, we reconstruct the mass of candidate stop events and fit the observed mass spectrum to a combination of standard model processes and stop signal. No evidence of {tilde t}{sub 1}{tilde {bar 1}}{sub 1} production is found, therefore we set 95% C.L. limits on the masses of the stop and the neutralino for several values of the chargino mass and the branching ratio {Beta} ({tilde {chi}}{sub 1}{sup {+-}} {yields} {tilde {chi}}{sub 1}{sup 0}{ell}{sup {+-}}{nu}).

  11. Universal Mass Texture, CP violation and Quark-Lepton Complementarity

    E-Print Network [OSTI]

    Canales, F Gonzalez; Barranco, J

    2010-01-01T23:59:59.000Z

    Recent measurements of the neutrino and quark mixing angles satisfy the empirical relations called quark-lepton complementarity. These empirical relations suggests the existence of a correlation between the mixing matrices of leptons and quarks. In this work, we examine the possibility that this correlation between the mixing angles of quarks and leptons originates in the similar hierarchy of quarks and charged lepton masses and the seesaw mechanism type I, that gives mass to the Majorana neutrinos. We asssume that the similar mass hierarchies of charged lepton and quark masses allows us to represent all the mass matrices of Dirac fermions in terms of a two zeroes Fritzsch texture.

  12. Universal mass matrix for quarks and leptons and CP violation

    SciTech Connect (OSTI)

    Barranco, J.; Gonzalez Canales, F.; Mondragon, A. [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Am Muehlenberg 1, D-14476 Golm (Germany); Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 04510, Mexico D.F. (Mexico)

    2010-10-01T23:59:59.000Z

    The measurements of the neutrino and quark mixing angles satisfy the empirical relations called quark-lepton complementarity. These empirical relations suggest the existence of a correlation between the mixing matrices of leptons and quarks. In this work, we examine the possibility that this correlation between the mixing angles of quarks and leptons originates in the similar hierarchy of quarks and charged lepton masses and the seesaw mechanism type I, that gives mass to the Majorana neutrinos. We assume that the similar mass hierarchies of charged lepton and quark masses allows us to represent all the mass matrices of Dirac fermions in terms of a universal form with four texture zeroes.

  13. Searches for the SM Higgs Boson in Association with Top Quarks at LHC

    E-Print Network [OSTI]

    Zanzi, Daniele; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    Summary of the Run-I results of the searches for the SM Higgs boson produced in associations with top quarks at the LHC. Results performed by both the ATLAS and CMS experiments are presented and include the searches for the Higgs boson produced in association with either a top quark pair or a single top quark. Measurements of the top Yukawa coupling from the combinations of all CMS and ATLAS Higgs boson measurements are also presented together with prospects for the LHC Run-II. Talk for the 25th International Workshop on Weak Interactions and Neutrinos (WIN2015), 08/06/15 in Heidelberg.

  14. Quark mass thresholds in QCD thermodynamics

    E-Print Network [OSTI]

    M. Laine; Y. Schroder

    2006-05-05T23:59:59.000Z

    We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high temperature QCD. The indication from leading order that the charm quark plays a visible role at surprisingly low temperatures, is confirmed. We also sketch a way to obtain phenomenological estimates relevant for generic expansion rate computations at temperatures between the QCD and electroweak scales, pointing out where improvements over the current knowledge are particularly welcome.

  15. Resolving the Tevatron top quark forward-backward asymmetry puzzle

    E-Print Network [OSTI]

    Michal Czakon; Paul Fiedler; Alexander Mitov

    2014-11-11T23:59:59.000Z

    We determine the dominant missing Standard Model (SM) contribution to the top quark pair forward-backward asymmetry at the Tevatron. Contrary to past expectations, we find a large, around 27%, shift relative to the well-known value of the inclusive asymmetry in next-to-leading order (NLO) QCD. Combining all known Standard Model corrections, we find that AFB^{SM} = 0.095 +- 0.007. This value is in perfect agreement with the latest D0 measurement \\cite{Abazov:2014cca} AFB^{D0} = 0.106+- 0.03 and about 1.5sigma below that of CDF \\cite{Aaltonen:2012it} AFB^{CDF} =0.164 +- 0.047. Our result is derived from a fully differential calculation of the next-to-next-to leading order (NNLO) QCD corrections to inclusive top pair production at hadron colliders and includes - without any approximation - all partonic channels contributing to this process. This is the first complete fully differential calculation in NNLO QCD of a two-to-two scattering process with all coloured partons.

  16. Top physics prospects at LHC

    E-Print Network [OSTI]

    Florian Beaudette

    2005-06-24T23:59:59.000Z

    With a high instantaneous luminosity and the large top quark pair production cross section, the Large Hadron Collider (LHC) will be a "top factory" allowing the analysis of millions of top events. After a short description of the top quark pair production mechanism and the cross section measurement, the accuracy of the top mass measurement needed for a sound consistency check of the Standard Model is briefly discussed. Different top mass measurement methods are presented. The observability of the single top quark production is described. Finally the observation of the Higgs boson produced in association with a top quark pair is discussed.

  17. Search for W-prime Boson Resonances Decaying to a Top Quark and a Bottom Quark

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; /Dubna, JINR; Abolins, M.; /Oklahoma U.; Acharya, B.S.; /Michigan State U.; Adams, M.; /Tata Inst.; Adams, T.; /Illinois U., Chicago; Aguilo, E.; /Florida State U.; Ahn, S.H.; /York U., Canada; Ahsan, M.; /Korea U., KODEL; Alexeev, G.D.; /Kansas State U.; Alkhazov, Georgiy; /Dubna, JINR /St. Petersburg, INP /Northeastern U.

    2008-03-01T23:59:59.000Z

    We search for the production of a heavy W{prime} gauge boson that decays to third generation quarks in 0.9 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron collider. We find no significant excess in the final-state invariant mass distribution and set upper limits on the production cross section times branching fraction. For a left-handed W{prime} boson with SM couplings, we set a lower mass limit of 731 GeV. For right-handed W{prime} bosons, we set lower mass limits of 739 GeV if the W{prime} boson decays to both leptons and quarks and 768 GeV if the W{prime} boson decays only to quarks. We also set limits on the coupling of the W{prime} boson to fermions as a function of its mass.

  18. Top pair production cross section at s**(1/2) = 1.96 TeV and a search for v + a current in top quark decay

    SciTech Connect (OSTI)

    Cabrera, S.; /Valencia U., IFIC

    2006-09-01T23:59:59.000Z

    Possible effects from physics beyond the Standard Model have been investigated in top quark decays from a data sample enriched in t{bar t} events produced in p{bar p} collisions at {radical}s = 1.96 TeV with an integrated luminosity of approximately 700 pb{sup -1} and collected with the CDF II detector. The combined t{bar t} production cross section measurement 7.3 {+-} 0.9 pb agrees with the QCD NLO predictions: 6.7 {+-} 0.8 pb assuming m{sub top} = 175 GeV/c{sup 2}. The fraction of the V + A current in top quark decay, f{sub V+A}, is determined using the invariant mass of the charged lepton and the bottom quark jet in the decay chain t {yields} Wb {yields} {ell}{nu}b (where {ell} = e or {mu}). The measured value f{sub V+A} = - 0.06 {+-} 0.25 under the assumption m{sub top} = 175 GeV/c{sup 2} is in agreement with the Standard Model. They set an upper limit on f{sub V+A} of 0.29 at the 95% confidence level.

  19. Dressed Quark Mass Dependence of Pion and Kaon Form Factors

    E-Print Network [OSTI]

    Y. Ninomiya; W. Bentz; I. C. Clot

    2015-01-27T23:59:59.000Z

    The structure of hadrons is described well by the Nambu--Jona-Lasinio (NJL) model, which is a chiral effective quark theory of QCD. In this work we explore the electromagnetic structure of the pion and kaon using the three-flavor NJL model, including effects of confinement and a pion cloud at the quark level. In the calculation there is only one free parameter, which we take as the dressed light quark ($u$ and $d$) mass. In the regime where the dressed light quark mass is approximately $0.25\\,$GeV, we find that the calculated values of the kaon decay constant, current quark masses, and quark condensates are consistent with experiment and QCD based analyses. We also investigate the dressed light quark mass dependence of the pion and kaon electromagnetic form factors, where comparison with empirical data and QCD predictions also favors a dressed light quark mass near $0.25\\,$GeV.

  20. Study of heavy-flavor quarks produced in association with top-quark pairs at ?s = 7 TeV using the ATLAS detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    Using a sample of dilepton top-quark pair (t[bar over t]) candidate events, a study is performed of the production of top-quark pairs together with heavy-flavor (HF) quarks, the sum of t[bar over t] + b + X and t[bar over ...

  1. Search for the associated production of the Higgs boson with a top-quark pair

    SciTech Connect (OSTI)

    Khachatryan, Vardan [Yerevan Physics Institute (Armenia)

    2014-09-01T23:59:59.000Z

    A search for the standard model Higgs boson produced in association with a top-quark pair (t?tH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb? and 19.7 fb? collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H ? hadrons, H ? photons, and H ? leptons. The results are characterized by an observed t?tH signal strength relative to the standard model cross section, ?=?/?SM, under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is ? = 2.8 1.0 for a Higgs boson mass of 125.6 GeV.

  2. Search for the associated production of the Higgs boson with a top-quark pair

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-09-01T23:59:59.000Z

    A search for the standard model Higgs boson produced in association with a top-quark pair (t?tH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb? and 19.7 fb? collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H ? hadrons, H ? photons, and H ? leptons. The results are characterized by an observed t?tH signal strength relative to the standard model cross section, ?=?/?SM, under the assumption that the Higgs boson decays as expected in themorestandard model. The best fit value is ? = 2.8 1.0 for a Higgs boson mass of 125.6 GeV.less

  3. Search for the associated production of the Higgs boson with a top-quark pair

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan [Yerevan Physics Institute (Armenia)

    2014-09-01T23:59:59.000Z

    A search for the standard model Higgs boson produced in association with a top-quark pair (t?tH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb? and 19.7 fb? collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H ? hadrons, H ? photons, and H ? leptons. The results are characterized by an observed t?tH signal strength relative to the standard model cross section, ?=?/?SM, under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is ? = 2.8 1.0 for a Higgs boson mass of 125.6 GeV.

  4. Top physics results at CDF

    SciTech Connect (OSTI)

    Vickey, Trevor; /Illinois U., Urbana

    2005-05-01T23:59:59.000Z

    The most recent results on top quark physics at CDF are reported. Measurements of cross-section and mass are presented, and the status of single top quark production searches are discussed. The results obtained from probing various top quark properties are also presented.

  5. Combination of measurements of the top-quark pair production cross section from the Tevatron Collider

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We combine six measurements of the inclusive top-quark pair (t[bar over t]) production cross section (?[subscript tt]-) from data collected with the CDF and D0 detectors at the Fermilab Tevatron with proton-antiproton ...

  6. Top quark forward-backward asymmetry, flavor-changing neutral-current decays, and like-sign pair production as a joint probe of new physics

    SciTech Connect (OSTI)

    Cao Junjie [College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 (China); Wang Lin [College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 (China); Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Academia Sinica, Beijing 100190 (China); Wu Lei; Yang Jinmin [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Academia Sinica, Beijing 100190 (China)

    2011-10-01T23:59:59.000Z

    The anomaly of the top quark forward-backward asymmetry A{sub FB}{sup t} observed at the Tevatron can be explained by the t-channel exchange of a neutral gauge boson (Z{sup '}) which has sizable flavor-changing coupling for top and up quarks. This gauge boson can also induce the top quark flavor-changing neutral-current (FCNC) decays and the like-sign top pair production at the LHC. In this work, we focus on two models which predict such a Z', namely, the left-right model and the U(1){sub X} model, to investigate the correlated effects on A{sub FB}{sup t}, the FCNC decays t{yields}uV (V=g, Z, {gamma}) and the like-sign top pair production at the LHC. We also pay special attention to the most recently measured A{sub FB}{sup t} in the large top pair invariant mass region. We find that under the current experimental constraints both models can alleviate the deviation of A{sub FB}{sup t} and, meanwhile, enhance the like-sign top pair production to the detectable level of the LHC. We also find that the two models give different predictions for the observables and their correlations, and thus they may even be distinguished by jointly studying these top quark observables.

  7. Search for electroweak single top quark production in 1.96-TeV proton-antiproton collisions

    SciTech Connect (OSTI)

    Stelzer, Bernd; /Toronto U.

    2005-01-01T23:59:59.000Z

    This thesis describes the first search for electroweak single top quark production in proton-antiproton collisions at a center of mass energy of 1.96 TeV. The data sample used for this analysis corresponds to 162 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. The search is performed by doing a classic maximum likelihood fit to the H{sub T} distribution in data. The kinematic variable H{sub T} is the scalar sum of transverse energies of all final state particles in the event. This variable has the advantage that its distribution looks very similar for both contributing (s-channel and t-channel) single top processes, but is different for background processes. The combination of both channels to one signal improves the sensitivity of the search. No significant evidence for electroweak single top quark production is found and we set an upper limit at the 95% confidence level on the combined single top quark production cross section of 17.8 pb.

  8. Quark masses, the Dashen phase, and gauge field topology

    SciTech Connect (OSTI)

    Creutz, Michael, E-mail: creutz@bnl.gov

    2013-12-15T23:59:59.000Z

    The CP violating Dashen phase in QCD is predicted by chiral perturbation theory to occur when the updown quark mass difference becomes sufficiently large at fixed down-quark mass. Before reaching this phase, all physical hadronic masses and scattering amplitudes are expected to behave smoothly with the up-quark mass, even as this mass passes through zero. In Euclidean space, the topological susceptibility of the gauge fields is positive at positive quark masses but diverges to negative infinity as the Dashen phase is approached. A zero in this susceptibility provides a tentative signal for the point where the mass of the up quark vanishes. I discuss potential ambiguities with this determination. -- Highlights: The CP violating Dashen phase in QCD occurs when the up quark mass becomes sufficiently negative. Before reaching this phase, all physical hadronic masses and scattering amplitudes behave smoothly with the up-quark mass. The topological susceptibility of the gauge fields diverges to negative infinity as the Dashen phase is approached. A zero in the topological susceptibility provides a tentative signal for the point where the mass of the up quark vanishes. The universality of this definition remains unproven. Potential ambiguities are discussed.

  9. Measurement of the Electric Charge of the Top Quark in $\\boldsymbol{t\\bar{t}}$ Events

    E-Print Network [OSTI]

    D0 Collaboration

    2014-09-25T23:59:59.000Z

    We present a measurement of the electric charge of top quarks using $t\\bar{t}$ events produced in $p\\bar{p}$ collisions at the Tevatron. The analysis is based on fully reconstructed $t\\bar{t}$ pairs in lepton+jets final states. Using data corresponding to 5.3 $\\rm fb^{-1}$ of integrated luminosity, we exclude the hypothesis that the top quark has a charge of $Q=-4/3\\,e$ at a significance greater than 5 standard deviations. We also place an upper limit of 0.46 on the fraction of such quarks that can be present in an admixture with the standard model top quarks ($Q=+2/3\\,e$) at a 95\\% confidence level.

  10. Measurement of Top Quark Polarization in Top-Antitop Events from Proton-Proton Collisions at ?s = 7 TeV Using the ATLAS Detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7??fb[superscript ?1] of proton-proton collision data recorded with the ATLAS detector at the Large Hadron ...

  11. QCD Thermodynamics with an almost realistic quark mass spectrum

    E-Print Network [OSTI]

    C. Schmidt

    2006-01-25T23:59:59.000Z

    We will report on the status of a new large scale calculation of thermodynamic quantities in QCD with light up and down quarks corresponding to an almost physical light quark mass value and a heavier strange quark mass. These calculations are currently being performed on the QCDOC Teraflops computers at BNL. We will present new lattice calculations of the transition temperature and various susceptibilities reflecting properties of the chiral transition. All these quantities are of immediate interest for heavy ion phenomenology.

  12. Interpretations and implications of the top quark rapidity asymmetries A FB t and A FB ?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Berger, Edmond L.; Cao, Qing-Hong; Chen, Chuan-Ren; Zhang, Hao

    2013-07-01T23:59:59.000Z

    Forward-backward asymmetries AtFB and AlFB are observed in the top-quark t rapidity distribution and in the rapidity distribution of charged leptons l from top-quark decay at the Tevatron proton-antiproton collider, and a charge asymmetry AC is seen in proton-proton collisions at the Large Hadron Collider (LHC). In this paper, we update our previous studies of the Tevatron asymmetries using the most recent data. We provide expectations for AC at the LHC based first on simple extrapolations from the Tevatron, and second based on new physics models that can explain the Tevatron asymmetries. We examine the relationship of the two asymmetries AtFB and AlFB. We show their connection through the (VA) spin correlation between the charged lepton and the top quark with different polarization states. We show that the ratio of the two asymmetries provides independent insight into the physics interpretation of the top-quark asymmetry. We emphasize the value of the measurement of both asymmetries, and we conclude that a model which produces more right-handed than left-handed top quarks is suggested by the present Tevatron data.

  13. Measurement of the electroweak top quark production cross section and the CKM matrix element Vtb with the D0 experiment

    SciTech Connect (OSTI)

    Kirsch, Matthias; /Aachen, Tech. Hochsch.

    2009-06-01T23:59:59.000Z

    At particle accelerators the Standard Model has been tested and will be tested further to a great precision. The data analyzed in this thesis have been collected at the world's highest energetic-collider, the Tevatron, located at the Fermi National Accelerator Laboratory (FNAL) in the vicinity of Chicago, IL, USA. There, protons and antiprotons are collided at a center-of-mass energy of {radical}s = 1.96 TeV. The discovery of the top quark was one of the remarkable results not only for the CDF and D0 experiments at the Tevatron collider, but also for the Standard Model, which had predicted the existence of the top quark because of symmetry arguments long before already. Still, the Tevatron is the only facility able to produce top quarks. The predominant production mechanism of top quarks is the production of a top-antitop quark pair via the strong force. However, the Standard Model also allows the production of single top quarks via the electroweak interaction. This process features the unique opportunity to measure the |V{sub tb}| matrix element of the Cabbibo-Kobayashi-Maskawa (CKM) matrix directly, without assuming unitarity of the matrix or assuming that the number of quark generations is three. Hence, the measurement of the cross section of electroweak top quark production is more than the technical challenge to extract a physics process that only occurs one out of ten billion collisions. It is also an important test of the V-A structure of the electroweak interaction and a potential window to physics beyond the Standard Model in the case where the measurement of |V{sub tb}| would result in a value significantly different from 1, the value predicted by the Standard Model. At the Tevatron two production processes contribute significantly to the production of single top quarks: the production via the t-channel, also called W-gluon fusion, and the production via the s-channel, known as well as W* process. This analysis searches for the combined s+t channel production cross section, assuming the ratio of s-channel production over t-channel production is realized in nature as predicted by the Standard Model. A data set of approximately 1 fb{sup -1} is analyzed, the data set used by the D0 collaboration to claim evidence for single top quark production. Events with two, three, and four jets are used in the analysis if they contain one or two jets that were tagged as originating from the decay of a b hadron, an isolated muon or electron, and a significant amount of missing transverse energy. This selection of events follows the signature that the single top quark events are expected to show in the detector. In the meantime, both collaborations D0 and CDF have analyzed a larger data set and have celebrated the joint observation of single top quark production. The novelty of the analysis presented here is the way discriminating observables are determined. A so-called Multi-Process Factory evaluates each event under several hypotheses. A common analysis technique for example in top quark properties studies is to reconstruct the intermediate particles in the decay chain of the signal process from the final state objects measured in the various subdetectors. An essential part of such a method is to resolve the ambiguities that arise in the assignment of the final state objects to the partons of the decay chain. In a Multi-Process Factory this approach is extended and not only the decay chain of the signal process is reconstructed, but also the decay chains of the most important background processes. From the numerous possible event configurations for each of the signal and background decay chains the most probable configuration is selected based on a likelihood measure. Properties of this configuration, such as mass of the reconstructed top quark, are then used in a multivariate analysis technique to separate the expected signal contribution from the background processes. The technique which is used is called Boosted Decision Trees and has only recently been introduced in high energy physics analyses. A Bayesian approach is use

  14. Electroweak production of the top quark in the Run II of the D0 experiment

    SciTech Connect (OSTI)

    Clement, Benoit

    2006-04-01T23:59:59.000Z

    The work exposed in this thesis deals with the search for electroweak production of top quark (single top) in proton-antiproton collisions at {radical}s = 1.96 TeV. This production mode has not been observed yet. Analyzed data have been collected during the Run II of the D0 experiment at the Fermilab Tevatron collider. These data correspond to an integrated luminosity of 370 pb{sup -1}. In the Standard Model, the decay of a top quark always produce a high momentum bottom quark. Therefore bottom quark jets identification plays a major role in this analysis. The large lifetime of b hadrons and the subsequent large impact parameters relative to the interaction vertex of charged particle tracks are used to tag bottom quark jets. Impact parameters of tracks attached to a jet are converted into the probability for the jet to originate from the primary vertex. This algorithm has a 45% tagging efficiency for a 0.5% mistag rate. Two processes (s and t channels) dominate single top production with slightly different final states. The searched signature consists in 2 to 4 jets with at least one bottom quark jet, one charged lepton (electron or muon) and missing energy accounting for a neutrino. This final state is background dominated and multivariate techniques are needed to separate the signal from the two main backgrounds: associated production of a W boson and jets and top quarks pair production. The achieved sensitivity is not enough to reach observation and we computed upper limits at the 95% confidence level at 5 pb (s-channel) and 4.3 pb (t-channel) on single top production cross-sections.

  15. Angular analysis of polarized top quark decay into B-mesons in two different helicity systems

    E-Print Network [OSTI]

    S. Mohammad Moosavi Nejad; Mahboobe Balali

    2014-10-16T23:59:59.000Z

    We calculate the ${\\cal O}(\\alpha_s)$ radiative corrections to the spin dependent differential decay rates of the process $t\\rightarrow b+W^+$. These are needed to study the angular distribution of the energy of hadrons produced in polarized top quark decays at next-to-leading order (NLO). In our previous work, we studied the angular distribution of the scaled-energy of bottom-flavored hadrons (B) from polarized top quark decays, using a specific helicity coordinate system where the top quark spin was measured relative to the bottom momentum (system~1). Here, we study the angular distribution of the energy spectrum of B-hadron in a different helicity system, where the top spin is specified relative to the W-momentum (system~2). These energy distributions are governed by the polarized and unpolarized rate functions which are related to the density matrix elements of the decay $t\\rightarrow W^++b$. Through this paper, we present our predictions of the B-hadron spectrum in the polarized and unpolarized top decay and shall compare the polarized results in two different helicity systems. These predictions can be used to determine the polarization states of top quarks and also provide direct access to the B-hadron fragmentation functions (FFs) and allow us to deepen our knowledge of the hadroniazation process.

  16. Top Physics at ATLAS

    E-Print Network [OSTI]

    Marcello Barisonzi

    2005-08-02T23:59:59.000Z

    The Large Hadron Collider LHC is a top quark factory: due to its high design luminosity, LHC will produce about 200 millions of top quarks per year of operation. The large amount of data will allow to study with great precision the properties of the top quark, most notably cross-section, mass and spin. The Top Physics Working Group has been set up at the ATLAS experiment, to evaluate the precision reach of physics measurements in the top sector, and to study the systematic effects of the ATLAS detector on such measurements. This reports give an overview of the main activities of the ATLAS Top Physics Working Group in 2004.

  17. Search for s-channel single top-quark production in protonproton collisions at ?s = 8 TeV with the ATLAS detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    This Letter presents a search at the LHC for s-channel single top-quark production in protonproton collisions at a centre-of-mass energy of 8 TeV. The analyzed data set was recorded by the ATLAS detector and corresponds ...

  18. Top quark production cross-section at the Tevatron Run 2

    SciTech Connect (OSTI)

    S. Cabrera

    2003-06-04T23:59:59.000Z

    The top quark pair production cross-section {sigma}{sub t{bar t}} has been measured in p{bar p} collisions at center of mass energies of 1.96 TeV using Tevatron Run 2 data. In the beginning of Run 2 both CDF and D0 {sigma}{sub t{bar t}} measurements in the dilepton channel t{bar t} {yields} WbW{bar b} {yields} {bar {ell}}{nu}{sub {ell}}b{ell}{prime} {bar {nu}}{sub {ell}{prime}}{bar b} and in the lepton plus jets channel t{bar t} {yields} WbW{bar b} {yields} q{bar q}{prime} b{ell}{bar {nu}}{sub {ell}}{bar b} + {bar {ell}}{nu}{sub {ell}}bq{bar q}{prime} {bar b} agree with the NLO (Next-to-Leading-Order) theoretical predictions. The presence of a top signal in Tevatron data has been reestablished.

  19. Search for a Heavy Particle Decaying to a Top Quark and a Light Quark in pp? Collisions at ?s=1.96??TeV

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present a search for a new heavy particle X produced in association with a top quark, pp? ?t(X?t? q) or pp? ?t? (X? ?tq? ), where q stands for up quarks and down quarks. Such a particle may explain the recent anomalous ...

  20. Calculation of the strange quark mass using domain wall fermions

    E-Print Network [OSTI]

    Tom Blum; Amarjit Soni; Matthew Wingate

    2000-09-18T23:59:59.000Z

    We present a first calculation of the strange quark mass using domain wall fermions. This paper contains an overview of the domain wall discretization and a pedagogical presentation of the perturbative calculation necessary for computing the mass renormalization. We combine the latter with numerical simulations to estimate the strange quark mass. Our final result in the quenched approximation is 95(26) MeV in the ${\\bar{MS}}$ scheme at a scale of 2 GeV. We find that domain wall fermions have a small perturbative mass renormalization, similar to Wilson quarks, and exhibit good scaling behavior.

  1. Measurement of differential cross sections of single top-quark production in the $t$ channel in proton-proton collisions at $\\sqrt{s} = 8$ TeV

    E-Print Network [OSTI]

    Steffen Rcker

    2014-11-25T23:59:59.000Z

    Differential measurements of single top quark $t$-channel cross sections as a function of the transverse momentum and the absolute value of the rapidity of the top quark are presented. The data collected by the CMS experiment at the LHC at a center-of-mass energy of 8 TeV corresponds to an integrated luminosity of 19.7 fb$^{-1}$. Leptonic decay channels of the top quark, with either a muon or an electron in the final state, are considered. Neural networks are used to separate signal from background contributions. After correcting for selection efficiencies and detector resolution with an unfolding technique, the resulting distributions are found to agree with predictions from different Monte Carlo generators within the estimated uncertainties.

  2. Measurement of R = B(t --> Wb)/B(t -->Wq) in Top-Quark-Pair Decays Using Dilepton Events and the Full CDF Run II Data Set

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero; et al.,

    2014-06-02T23:59:59.000Z

    We present a measurement of the ratio of the top-quark branching fractions R = B(t --> Wb)/B(t --> Wq) where q represents any quark flavor, in events with two charged leptons, imbalance in total transverse energy, and at least two jets. The measurement uses protonantiproton collision data at center-of-mass energy 1.96 TeV, corresponding to an integrated luminosity of 8.7 fb?1 collected with the Collider Detector at Fermilab during Run II of the Tevatron. We measure R to be 0.87 0.07, and extract the magnitude of the top-bottom quark coupling to be |Vtb| = 0.93 0.04, assuming three generations of quarks. Under these assumptions, a lower limit of |Vtb| > 0.85(0.87) at 95 (90) percent credibility level is set.

  3. Search for pair production of scalar top quarks in jets and missing transverse energy channel with the D0 detector

    SciTech Connect (OSTI)

    Shamim, Mansoora; /Kansas State U.

    2008-05-01T23:59:59.000Z

    This dissertation describes a search for the pair production of scalar top quarks, {tilde t}{sub 1}, using a luminosity of 995 pb{sup -1} of data collected in p{bar p} collisions with the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy {radical}s = 1.96 TeV. Both scalar top quarks are assumed to decay into a charm quark and a neutralino, {tilde {chi}}{sub 1}{sup 0}, where {tilde {chi}}{sub 1}{sup 0} is the lightest supersymmetric particle. This leads to a final state with two acoplanar charm jets and missing transverse energy. The yield of such events in data is found to be consistent with the expectations from known standard model processes. Sets of {tilde t}{sub 1} and {tilde {chi}}{sub 1}{sup 0} masses are excluded at the 95% confidence level that substantially extend the domain excluded by previous searches. With the theoretical uncertainty on the {tilde t}{sub 1} pair production cross section taken into account, the largest limit for m{sub {tilde t}{sub 1}} is m{sub {tilde t}{sub 1}} > 150 GeV, for m{sub {tilde {chi}}{sub 1}{sup 0}} = 65 GeV.

  4. Top physics at CDF

    SciTech Connect (OSTI)

    Julia Thom

    2004-06-24T23:59:59.000Z

    Precision studies of top quark properties are a primary goal of the Run II physics program at the Fermilab Tevatron. Marking the first stages of this program, the CDF collaboration presents recent results on top pair production cross section, single top physics and top mass, using between 109 and 200 pb{sup -1} of Run II data.

  5. Higgs boson production in association with top quarks in the POWHEG BOX

    E-Print Network [OSTI]

    Hartanto, Heribertus B; Reina, Laura; Wackeroth, Doreen

    2015-01-01T23:59:59.000Z

    We present results from the analytic calculation of top+antitop+Higgs hadronic production at Next-to-Leading Order in QCD interfaced with parton-shower Monte Carlo event generators in the POWHEG BOX framework. We consider kinematic distributions of the top quark and Higgs boson at the 8 TeV Large Hadron Collider and study the theoretical uncertainties due to specific choices of renormalization/factorization scales and parton-showering algorithms, namely PYTHIA and HERWIG. The importance of spin-correlations in the production and decay stages of a top/antitop quark is discussed on the example of kinematic distributions of leptons originating from the top/antitop decays. The corresponding code is now part of the public release of the POWHEG BOX.

  6. Early Top Physics with ATLAS

    E-Print Network [OSTI]

    J. Schieck

    2009-01-12T23:59:59.000Z

    The ATLAS detector is one of the two multi-purpose experiments located at the Large Hadron Collider (LHC) at CERN and is expected to collect first collision data in summer 2009. Due to the large top-quark production cross-section the LHC will function as a top-quark factory allowing to measure top-quark properties even at initial luminosities. We present some recently-performed studies, focussing on measurements of the top pair and single top production cross-sections with the first fb-1 of data. The potential for the measurement of other top-quark properties like the mass will be also briefly discussed.

  7. Measurements of the top - anti-top Production Cross Section at s**(1/2) = 1.96-TeV and Top Mass in the Dielectron Channel

    SciTech Connect (OSTI)

    Kozminski, Joseph Francis

    2005-05-01T23:59:59.000Z

    The first measurement of the top-antitop production cross section in proton-antiproton collisions at {radical}s = 1.96 TeV using 243 pb{sup -1} of data collected with the D0 detector at Fermilab is presented. In this analysis, only the dielectron final state is considered. Five events are observed, and 0.93 background events are expected. The measured cross section, after accounting for the expected branching ratio to the dielectron channel, is {sigma}{sub t{bar t}} = 14.9{sub -7.0}{sup +9.4}(stat){sub -1.8}{sup +2.5}(syst) {+-} 1.0 (lumi) pb, which agrees with the predicted cross section for top quarks with a mass of 175 GeV. In addition, a first-pass at a measurement of the top mass using the neutrino-weighting method is presented. This measurement is also performed in the dielectron channel using the five events observed in the cross section measurement.

  8. Search for Associated Production of a Single Top Quark and a Higgs Boson in Leptonic Channels

    E-Print Network [OSTI]

    CMS Collaboration

    2015-01-01T23:59:59.000Z

    A search for the production of a Higgs boson in association with a single top quark is presented, focusing on leptonic signatures provided by the $\\mathrm{H}\\rightarrow\\mathrm{W}\\mathrm{W}$ and $\\mathrm{H}\\rightarrow\\tau\\tau$ decay modes.

  9. Combination of CDF and D0 measurements of the W boson helicity in top quark decays

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.75.4??fb[superscript ...

  10. Exclusion of an Exotic Top Quark with-4/3 Electric Charge Using Soft Lepton Tagging

    E-Print Network [OSTI]

    Paus, Christoph M. E.

    We present a measurement of the electric charge of the top quark using pp[over-bar] collisions corresponding to an integrated luminosity of 2.7??fb[superscript -1] at the CDF II detector. We reconstruct tt[over-bar] events ...

  11. Search for the associated production of the Higgs boson with a top-quark pair

    E-Print Network [OSTI]

    CMS Collaboration

    A search for the standard model Higgs boson produced in association with a top-quark pair (ttH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb?1 and 19.7 fb?1 collected in pp ...

  12. Quark mass functions and pion structure in Minkowski space

    SciTech Connect (OSTI)

    Biernat, Elmer P. [CFTP, Institute Superior Tecnico; Gross, Franz L. [JLAB; Pena, Maria Teresa [CFTP, Institute Superior Tecnico; Stadler, Alfred [University of Evora

    2014-03-01T23:59:59.000Z

    We present a study of the dressed quark mass function and the pion structure in Minkowski space using the Covariant Spectator Theory (CST). The quark propagators are dressed with the same kernel that describes the interaction between different quarks. We use an interaction kernel in momentum space that is a relativistic generalization of the linear confining q-qbar potential and a constant potential shift that defines the energy scale. The confining interaction has a Lorentz scalar part that is not chirally invariant by itself but decouples from the equations in the chiral limit and therefore allows the Nambu--Jona-Lasinio (NJL) mechanism to work. We adjust the parameters of our quark mass function calculated in Minkowski-space to agree with LQCD data obtained in Euclidean space. Results of a calculation of the pion electromagnetic form factor in the relativistic impulse approximation using the same mass function are presented and compared with experimental data.

  13. The Dark Top

    E-Print Network [OSTI]

    David Poland; Jesse Thaler

    2008-12-08T23:59:59.000Z

    We present a class of composite Higgs models in which the particle that regulates the top quark contribution to the Higgs potential is also a weakly-interacting dark matter candidate. This color-neutral "dark top" is related to the standard model top quark through a large global symmetry. Because the same couplings that control the Higgs potential also determine various dark matter cross sections, the dark top scenario is quite predictive once the dark top mass and various quantum numbers are specified. We construct two concrete examples of dark top models with plausible UV completions and study their dark matter properties and LHC signatures.

  14. Search for H ? ?? produced in association with top quarks and constraints on the Yukawa coupling between the top quark and the Higgs boson using data taken at 7 TeV and 8 TeV with the ATLAS detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    A search is performed for Higgs bosons produced in association with top quarks using the diphoton decay mode of the Higgs boson. Selection requirements are optimized separately for leptonic and fully hadronic final states ...

  15. First Measurement of the Fraction of Top Quark Pair Production Through Gluon-Gluon Fusion

    E-Print Network [OSTI]

    CDF Collaboration; T. Aaltonen

    2008-04-08T23:59:59.000Z

    We present the first measurement of the fraction of top quark pair production through gluon-gluon fusion. We use 0.96/fb of s**(1/2)=1.96 TeV p-pbar collision data recorded with the CDF II detector at Fermilab. We identify the candidate t-tbar events with a high-energy charged lepton, a neutrino candidate, and four or more jets. Using charged particles with low transverse momentum in t-tbar events, we find the fraction of top quark pair production through gluon-gluon fusion to be 0.07+/-0.14(stat)+/-0.07(syst), corresponding to a 95% confidence level upper limit of 0.33, in agreement with the standard model NLO prediction of 0.15+/-0.05.

  16. Threshold Corrections to the Bottom Quark Mass Revisited

    E-Print Network [OSTI]

    Archana Anandakrishnan; B. Charles Bryant; Stuart Raby

    2015-01-29T23:59:59.000Z

    Threshold corrections to the bottom quark mass are often estimated under the approximation that tan$\\beta$ enhanced contributions are the most dominant. In this work we revisit this common approximation made to the estimation of the supersymmetric threshold corrections to the bottom quark mass. We calculate the full one-loop supersymmetric corrections to the bottom quark mass and survey a large part of the phenomenological MSSM parameter space to study the validity of considering only the tan$\\beta$ enhanced corrections. Our analysis demonstrates that this approximation underestimates the size of the threshold corrections by $\\sim$12.5% for most of the considered parameter space. We discuss the consequences for fitting the bottom quark mass and for the effective couplings to Higgses. We find that it is important to consider the additional contributions when fitting the bottom quark mass but the modifications to the effective Higgs couplings are typically $\\mathcal{O}$(few)% for the majority of the parameter space considered.

  17. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp? Collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; lvarez Gonzlez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anz, F.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; dAscenzo, N.; Datta, M.; de Barbaro, P.; DellOrso, M.; Demortier, L.; Deninno, M.; Devoto, F.; dErrico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; DOnofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Fuks, B.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; Gonzlez, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martnez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.

    2012-05-01T23:59:59.000Z

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb? of Tevatron pp collisions at ?s=1.96 TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp??t+D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0150 GeV/c.

  18. Top Physics at CDF

    SciTech Connect (OSTI)

    Moon, Chang-Seong

    2011-06-01T23:59:59.000Z

    We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions at a center of mass energy of {radical}s = 1.96 TeV analyzed by the CDF collaboration. Thanks to this large data sample, precision top quark measurements are now a reality at the Tevatron. Further, several new physics signals could appear in this large dataset. We will present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  19. Top Physics at CDF

    E-Print Network [OSTI]

    Chang-Seong Moon

    2011-07-01T23:59:59.000Z

    We present the recent results of top-quark physics using up to 6 fb$^{-1}$ of $p \\bar p$ collisions at a center of mass energy of $\\sqrt s$ = 1.96 TeV analyzed by the CDF collaboration. Thanks to this large data sample, precision top quark measurements are now a reality at the Tevatron. Further, several new physics signals could appear in this large dataset. We will present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  20. Measurement of the Inclusive Leptonic Asymmetry in Top-Quark Pairs that Decay to Two Charged Leptons at CDF

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We measure the inclusive forwardbackward asymmetry of the charged-lepton pseudorapidities from top-quark pairs produced in protonantiproton collisions and decaying to final states that contain two charged leptons (electrons ...

  1. Search for the Standard Model Higgs Boson Produced in Association with Top Quarks Using the Full CDF Data Set

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    A search is presented for the standard model Higgs boson produced in association with top quarks using the full Run II proton-antiproton collision data set, corresponding to 9.45??fb[superscript -1], collected by the ...

  2. Constituent quark masses obtained from hadron masses with contributions of Fermi-Breit and Glozman-Riska hyperfine interactions

    SciTech Connect (OSTI)

    Borka Jovanovic, V.; Borka, D. [Laboratory of Physics (010), Vinca Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Ignjatovic, S. R. [Department of Physics, Faculty of Science, University of Banja Luka, Mladena Stojanovica 2, 78000 Banja Luka (Bosnia and Herzegowina); Jovanovic, P. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

    2010-12-01T23:59:59.000Z

    We use the color-spin and flavor-spin interaction Hamiltonians with SU(3) flavor symmetry breaking to obtain meson and baryon mass formulas. Adjusting these masses with experimental masses we determine the constituent quark masses. We discuss the constituent quark masses obtained from meson and baryon mass fits. The results for constituent quark masses are very similar in the case of two different phenomenological models: Fermi-Breit and Glozman-Riska hyperfine interactions.

  3. Measurement of the charge asymmetry in top-quark pair production in proton-proton collisions at sqrt(s) = 7 TeV

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; Khachatryan, Vardan; Sirunyan, Albert M.; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; /Yerevan Phys. Inst. /Vienna, OAW /Minsk, High Energy Phys. Ctr. /Antwerp U., WISINF /Vrije U., Brussels /Brussels U. /Gent U. /Louvain U. /UMH, Mons /Rio de Janeiro, CBPF /Rio de Janeiro State U.

    2011-12-01T23:59:59.000Z

    The difference in angular distributions between top quarks and antiquarks, commonly referred to as the charge asymmetry, is measured in pp collisions at the LHC with the CMS experiment. The data sample corresponds to an integrated luminosity of 1.09 fb{sup -1} at a centre-of-mass energy of 7 TeV. Top-quark pairs are selected in the final state with an electron or muon and four or more jets. At least one jet is identified as originating from b-quark hadronization. The charge asymmetry is measured in two variables, one based on the pseudorapidities ({eta}) of the top quarks and the other on their rapidities (y). The results A{sub C}{sup {eta}} = -0.017 {+-} 0.032(stat.){sub -0.036}{sup +0.025}(syst.) and A{sub C}{sup y} = -0.013 {+-} 0.028(stat.){sub -0.031}{sup +0.029}(syst.) are consistent within uncertainties with the standard-model predictions.

  4. Searches for New Physics in Top Decays at D0

    SciTech Connect (OSTI)

    Pleier, Marc-Andre; /Brookhaven

    2011-08-01T23:59:59.000Z

    The Tevatron proton-antiproton collider at Fermilab with its centre of mass energy of 1.96 TeV allows for pair production of top quarks and the study of top quark decay properties. This report reflects the current status of measurements of the W boson helicity in top quark decays and the ratio of top quark branching fractions as well as searches for neutral current top quark decays and pair production of fourth generation t' quarks, performed by the D0 Collaboration utilising datasets of up to 5.4 fb{sup -1}.

  5. A Highly Granular Silicon-Tungsten Electromagnetic Calorimeter and Top Quark Production at the International Linear Collider

    E-Print Network [OSTI]

    Roun, J

    2014-01-01T23:59:59.000Z

    This thesis deals with two aspects of the International Linear Collider (ILC) which is a project of a linear electron-positron collider of up to at least 500 GeV center of mass energy. The first aspect is the development of a silicon-tungsten electromagnetic calorimeter (SiW-ECAL) for one of the detectors of the ILC. The concept of this detector is driven by the ILC beam specifications and by the Particle Flow Algorithm (PFA). This requires highly granular calorimeter and very compact one with integrated electronics. To prove the capability of the SiW- ECAL a technological prototype has been built and tested in test beam at DESY. The results are presented here, and show, after the calibration procedure a signal over noise ratio of 10, even in the power pulsing mode. The second aspect is the study of one of the important physics channels of the ILC, the top anti-top quark pairs production. The main goal of this study is to determine the precision that we can expect at the ILC on the top coupling with the W bos...

  6. Search for a heavy particle decaying to a top quark and a light quark in $p\\bar{p}$ collisions at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Yale U.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U. /Dubna, JINR

    2012-03-01T23:59:59.000Z

    We present a search for a new heavy particle M produced in association with a top quark, p{bar p} {yields} t(M {yields} {bar t}q) or p{bar p} {yields} {bar t}({bar M} {yields} t{bar q}), where q stands for up quarks and down quarks. Such a particle may explain the recent anomalous measurements of top-quark forward-backward asymmetry. If the light-flavor quark (q) is reconstructed as a jet (j), this gives a {bar t}+j or t+j resonance in t{bar t}+jet events, a previously unexplored experimental signature. In a sample of events with exactly one lepton, missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb{sup -1} collected by the CDF II detector, we find the data to be consistent with the standard model. We set cross-section upper limits on the production (p{bar p} {yields} Mt or {bar M} {bar t}) at 95% confidence level from 0.61 pb to 0.02 pb for M masses ranging from 200 GeV/c{sup 2} to 800 GeV/c{sup 2}, respectively.

  7. Top Threshold Physics

    E-Print Network [OSTI]

    Andre H. Hoang

    2006-04-21T23:59:59.000Z

    Running a future Linear Collider at the top pair threshold allows for precise measurements of the mass, the widths and the couplings of the top quark. I give a nontechnical review on recent theoretical developments and the theory status in top threshold physics concerning QCD corrections and top quark finite lifetime and electroweak effects. I also discuss threshold physics in the context of measurements of the top Yukawa coupling from $e^+e^-\\to t\\bar t H$ and of squark pair production.

  8. Search for the standard model Higgs boson produced in association with top quarks using the full CDF data set

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-08-01T23:59:59.000Z

    A search is presented for the standard model Higgs boson produced in association with top quarks using the full Run II proton-antiproton collision data set, corresponding to 9.45 fb{sup -1}, collected by the Collider Detector at Fermilab. No significant excess over the expected background is observed, and 95% credibility-level upper bounds are placed on the cross section {sigma}(t{bar t}H {yields} lepton + missing transverse energy + jets). For a Higgs boson mass of 125 GeV/c{sup 2}, we expect to set a limit of 12.6, and observe a limit of 20.5 times the standard model rate. This represents the most sensitive search for a standard model Higgs boson in this channel to date.

  9. Search for charged Higgs bosons in decays of top quarks in proton - antiproton collisions at s**(1/2) = 1.96 TeV

    SciTech Connect (OSTI)

    Yu, Geum Bong; /Rochester U.

    2009-08-01T23:59:59.000Z

    In this dissertation we report on the first direct search for charged Higgs bosons in decays of top quarks in p{bar p} collisions at {radical}s = 1.96 TeV. The search uses a data sample with an integrated luminosity of 2.2 fb{sup -1} collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t{bar t} candidates. We observe no evidence of charged Higgs bosons in top quark decays; hence 95% C.L. upper limits on the branching ratio are placed at {Beta}(t {yields} H{sup +}b) < 0.1 to 0.3 for charged Higgs boson masses of 60 to 150 GeV/c{sup 2} assuming {Beta}(H{sup +} {yields} c{bar s}) = 1.0 and {Beta}(t {yields} Wb)+{Beta}(t {yields} H{sup +}b) = 1.0. The upper limits on {Beta}(t {yields} H{sup +}b) are also used as model independent limits on the decay branching ratio of top quarks to any charged scalar bosons beyond the standard model.

  10. Top-Higgs and Top-pion phenomenology in the Top Triangle Moose model

    E-Print Network [OSTI]

    R. Sekhar Chivukula; Baradhwaj Coleppa; Heather E. Logan; Adam Martin; Elizabeth H. Simmons

    2011-01-31T23:59:59.000Z

    We discuss the deconstructed version of a topcolor-assisted technicolor model wherein the mechanism of top quark mass generation is separated from the rest of electroweak symmetry breaking. The minimal deconstructed version of this scenario is a "triangle moose" model, where the top quark gets its mass from coupling to a top-Higgs field, while the gauge boson masses are generated from a Higgsless sector. The spectrum of the model includes scalar (top-Higgs) and pseudoscalar (top-pion) states. In this paper, we study the properties of these particles, discuss their production mechanisms and decay modes, and suggest how best to search for them at the LHC.

  11. Search for standard model production of four top quarks in the lepton + jets channel in pp collisions at ? = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan [Yerevan Physics Inst. (YerPhI) (Armenia)

    2014-11-01T23:59:59.000Z

    A search is presented for standard model (SM) production of four top quarks (t?tt?t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6? recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM (t?tt?t) production is ?SM(t?tt?t). A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. The data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence level on the cross section for producing four top quarks in the SM, where a limit of 32 17 fb is expected.

  12. Search for standard model production of four top quarks in the lepton + jets channel in pp collisions at ? = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-11-01T23:59:59.000Z

    A search is presented for standard model (SM) production of four top quarks (t?tt?t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6? recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM (t?tt?t) production is ?SM(t?tt?t). A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. The data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence levelmoreon the cross section for producing four top quarks in the SM, where a limit of 32 17 fb is expected.less

  13. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp? Collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; lvarez Gonzlez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anz, F.; Apollinari, G.; Appel, J. A.; et al

    2012-05-01T23:59:59.000Z

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb? of Tevatron pp collisions at ?s=1.96 TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp??t+D as a function of the massmoreof the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0150 GeV/c.less

  14. Measurement of the top quark pair production cross-section in dimuon final states in proton-antiproton collisions at 1.96 TeV

    SciTech Connect (OSTI)

    Konrath, Jens Peter; /Freiburg U.

    2008-09-01T23:59:59.000Z

    Particle physics deals with the fundamental building blocks of matter and their interactions. The vast number of subatomic particles can be reduced to twelve fundamental fermions, which interact by the exchange of spin-1 particles as described in the Standard Model (SM) of particle physics. The SM provides the best description of the subatomic world to date, despite the fact it does not include gravitation. Following the relation {lambda} = h/p, where h is Planck's constant, for the examination of physics at subatomic scales with size {lambda} probes with high momenta p are necessary. These high energies are accessible through particle colliders. Here, particles are accelerated and brought to collision at interaction points at which detectors are installed to record these particle collisions. Until the anticipated start-up of the Large Hadron Collider at CERN, the Tevatron collider at Fermilab near Chicago is the highest energy collider operating in the world, colliding protons and anti-protons at a center-of-mass energy of {radical}s = 1.96 TeV. Its two interaction points are covered by the multi purpose particle detectors D0 and CDF. During the first data-taking period, known as Run I, the Tevatron operated at a center-of-mass energy of 1.8 TeV. This run period lasted from 1992 to 1996. During this period, the long-predicted top quark was discovered. From 1996 and 2001, the accelerator was upgraded to deliver higher instantaneous luminosities at its current center-of-mass energy. At the same time, the experiments were upgraded to take full advantage of the upgraded accelerator complex. The Tevatron is currently the only accelerator in the world with a sufficient energy to produce top quarks. Studying top quark production, decay and properties is an important part of the D0 and CDF physics programs. Because of its large mass, the top quark is a unique probe of the Standard Model, and an interesting environment to search for new physics. In this thesis, a measurement of the production cross-section of top quark pairs decaying to two muons is presented. In addition, a Monte Carlo study of the top quark spin correlation measurement was carried out. This thesis is laid out as follows: chapter two gives a short overview over the Standard Model of particle physics and the theoretical aspects of unpolarized and polarized top quark production and decay, chapter three describes the accelerator complex and the D0 experiment whose data is used in this analysis. The Reconstruction of events recorded with the D0 detector is explained in chapter four and the data and Monte Carlo samples used are presented in chapter five. Finally, the cross-section measurement is described in chapter six and the Monte Carlo study of top quark spin correlations in chapter seven.

  15. Search for standard model production of four top quarks in the lepton + jets channel in pp collisions at ? = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan [Yerevan Physics Inst. (YerPhI) (Armenia)

    2014-11-01T23:59:59.000Z

    A search is presented for standard model (SM) production of four top quarks (t?tt?t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6? recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM (t?tt?t) production is ?SM(t?tt?t). A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. The data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence level on the cross section for producing four top quarks in the SM, where a limit of 32 17 fb is expected.

  16. A like-sign dimuon charge asymmetry at Tevatron induced by the anomalous top quark couplings

    E-Print Network [OSTI]

    Jong Phil Lee; Kang Young Lee

    2011-10-26T23:59:59.000Z

    We show that the recently measured 3.2 $\\sigma$ deviations of the charge asymmetry of like-sign dimuon events from the standard model prediction by the D0 collaboration at Tevatron can be explained by introducing the anomalous right-handed top quark couplings. Combined analysis with the $\\bs$ and $\\bd$ mixings and $B \\to X_s \\gamma$ decays has been performed. We discuss how to discriminate the effects on the dimuon charge asymmetry of the anomalous $\\tsW$ and $\\tbW$ couplings.

  17. DZero (D0) Experiment Results for Top Quark Physics from the Fermilab Tevatron

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The D0 (DZero) Experiment is a worldwide collaboration of scientists conducting research on the fundamental nature of matter. The experiment is located at the Tevatron Collider, Fermilab. The research is focused on precise studies of interactions of protons and antiprotons and involves an intense search for subatomic clues that reveal the character of the building blocks of the universe. This web page provides access to Run II research results of the Top Quark Physics group, including preliminary, submitted, and published results. Figures and data plots are found in the directories with their respective papers.

  18. A global approach to top-quark flavor-changing interactions

    E-Print Network [OSTI]

    Gauthier Durieux; Fabio Maltoni; Cen Zhang

    2014-12-22T23:59:59.000Z

    We adopt a fully gauge-invariant effective-field-theory approach for parametrizing top-quark flavor-changing-neutral-current interactions. It allows for a global interpretation of experimental constraints (or measurements) and the systematic treatment of higher-order quantum corrections. We discuss some recent results obtained at next-to-leading order accuracy in QCD and perform, at that order, a first global analysis of a subset of the available experimental limits in terms of effective operator coefficients. We encourage experimental collaborations to adopt this approach and extend the analysis by using all information they have prime access to.

  19. Meson mass splittings in unquenched quark models (EEF70)

    E-Print Network [OSTI]

    T. J. Burns

    2014-11-10T23:59:59.000Z

    General results are obtained for meson mass splittings and mixings in unquenched (coupled-channel) quark models. Theorems derived previously in perturbation theory are generalised to the full coupled-channel system. A new formula is obtained for the mass splittings of physical states in terms of the splittings of the valence states. The S-wave hyperfine splitting decreases due to unquenching, but its relation to the vector $e^+e^-$ width is unchanged; this yields a prediction for the missing $\\eta_b(3S)$. The ordinary (quenched) quark model result that the P-wave hyperfine splitting vanishes also survives unquenching. A ratio of mass splittings used to discriminate quarkonium potential models is scarcely affected by unquenching.

  20. Study of top quark production and decays involving a tau lepton at CDF and limits on a charged Higgs boson contribution

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present an analysis of top-antitop quark production and decay into a tau lepton, tau neutrino, and bottom quark using data from 9??fb[superscript ?1] of integrated luminosity at the Collider Detector at Fermilab. Dilepton ...

  1. Neutrino masses and mixing, quark-lepton symmetry, and strong right-handed neutrino hierarchy

    SciTech Connect (OSTI)

    Dermisek, Radovan [Davis Institute for High Energy Physics, University of California, Davis, California 95616 (United States)

    2004-10-01T23:59:59.000Z

    Assuming the same form of all mass matrices as motivated by quark-lepton symmetry, we discuss conditions under which bilarge mixing in the lepton sector can be obtained with a minimal amount of fine-tuning requirements for possible models. We assume hierarchical mass matrices, dominated by the 3-3 element, with off-diagonal elements much smaller than the larger neighboring diagonal element. Characteristic features of this scenario are strong hierarchy in masses of right-handed neutrinos, and comparable contributions of both lighter right-handed neutrinos to the resulting left-handed neutrino Majorana mass matrix. Because of obvious quark-lepton symmetry, this approach can be embedded into grand unified theories. The mass of the lightest neutrino does not depend on details of a model in the leading order. The right-handed neutrino scale can be identified with the GUT scale in which case the mass of the lightest neutrino is given as (m{sub top}{sup 2}/M{sub GUT}) vertical bar U{sub {tau}}{sub 1} vertical bar{sup 2}.

  2. TRANSITION TEMPERATURE IN QCD WITH PHYSICAL LIGHT AND STRANGE QUARK MASSES.

    SciTech Connect (OSTI)

    KARSCH, F.

    2006-11-14T23:59:59.000Z

    We present results from a calculation of the transition temperature in QCD with two light (up, down) and one heavier (strange) quark mass as well as for QCD with three degenerate quark masses. Furthermore, we discuss first results from an ongoing calculation of the QCD equation of state with almost realistic light and strange quark masses.

  3. Top Quark Production Asymmetries AFBt and AFBl

    SciTech Connect (OSTI)

    Berger, Edmond L.; Cao, Qing-Hong; Chen, Chuan-Ren; Yu, Jiang-Hao; Zhang, Hao

    2012-02-01T23:59:59.000Z

    A large forward-backward asymmetry is seen in both the top quark rapidity distribution AFBt and in the rapidity distribution of charged leptons AFBl from top quarks produced at the Tevatron. We study the kinematic and dynamic aspects of the relationship of the two observables arising from the spin correlation between the charged lepton and the top quark with different polarization states. We emphasize the value of both measurements, and we conclude that a new physics model which produces more right-handed than left-handed top quarks is favored by the present data.

  4. Statistical Understanding of Quark and Lepton Masses in Gaussian Landscapes

    E-Print Network [OSTI]

    Lawrence J. Hall; Michael P. Salem; Taizan Watari

    2007-08-10T23:59:59.000Z

    The fundamental theory of nature may allow a large landscape of vacua. Even if the theory contains a unified gauge symmetry, the 22 flavor parameters of the Standard Model, including neutrino masses, may be largely determined by the statistics of this landscape, and not by any symmetry. Then the measured values of the flavor parameters do not lead to any fundamental symmetries, but are statistical accidents; their precise values do not provide any insights into the fundamental theory, rather the overall pattern of flavor reflects the underlying landscape. We investigate whether random selection from the statistics of a simple landscape can explain the broad patterns of quark, charged lepton, and neutrino masses and mixings. We propose Gaussian landscapes as simplified models of landscapes where Yukawa couplings result from overlap integrals of zero-mode wavefunctions in higher-dimensional supersymmetric gauge theories. In terms of just five free parameters, such landscapes can account for all gross features of flavor, including: the hierarchy of quark and charged lepton masses; small quark mixing angles, with 13 mixing less than 12 and 23 mixing; very light Majorana neutrino masses, with the solar to atmospheric neutrino mass ratio consistent with data; distributions for leptonic 12 and 23 mixings that are peaked at large values, while the distribution for 13 mixing is peaked at low values; and order unity CP violating phases in both the quark and lepton sectors. While the statistical distributions for flavor parameters are broad, the distributions are robust to changes in the geometry of the extra dimensions. Constraining the distributions by loose cuts about observed values leads to narrower distributions for neutrino measurements of 13 mixing, CP violation, and neutrinoless double beta decay.

  5. Measurement of the t-channel single top quark production cross section

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Abolins, Maris A.; /Michigan State U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Aguilo, Ernest; /Alberta U. /Simon Fraser U. /York U., Canada /McGill U.; Ahsan, Mahsana; /Kansas State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls /Northeastern U.

    2009-07-01T23:59:59.000Z

    The D0 collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb{sup -1} of p{bar p} collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14{sub -0.80}{sup +0.94} pb for the t-channel and 1.05 {+-} 0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.

  6. Measurement of the W-boson helicity fractions in top-quark decays at CDF

    SciTech Connect (OSTI)

    Chwalek, Thorsten; /Karlsruhe U., EKP

    2007-05-01T23:59:59.000Z

    We present a measurement of the fractions F{sub 0} and F{sub +} of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 955 pb{sup -1}. We select t{bar t} candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest-frame and the W momentum in the top-quark rest-frame. The cos{theta}* distribution in the data is determined by full kinematic reconstruction of the t{bar t} candidates. We find F{sub 0}= 0.59 {+-} 0.12(stat){sup +0.07}{sub -0.06}(syst) and F{sub +}=-0.03 {+-} 0.06(stat){sup +0.04}{sub -0.03}(syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W bosons of F{sub +} {le} 0.10 at the 95% confidence level.

  7. Search for a Supersymmetric Partner to the Top Quark in Final States with Jets and Missing Transverse Momentum at ?s=7??TeV with the ATLAS Detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    A search for direct pair production of supersymmetric top squarks (t[superscript ~][subscript 1]) is presented, assuming the t[subscript 1] decays into a top quark and the lightest supersymmetric particle, ?[superscript ...

  8. A Search for Flavour Changing Neutral Currents in Top-Quark Decays in pp Collision Data Collected With the ATLAS Detector at ?s = 7 TeV

    SciTech Connect (OSTI)

    Aad, Georges

    2014-09-30T23:59:59.000Z

    A search for flavour changing neutral current (FCNC) processes in top-quark decays by the ATLAS Collaboration is presented. Data collected from pp collisions at the LHC at a centre-of-mass energy of ?s = 7 TeV during 2011, corresponding to an integrated luminosity of 2.1 fb?1, were used. A search was performed for top-quark pair-production events, with one top quark decaying through the t ? Zq FCNC (q = u, c) channel, and the other through the Standard Model dominant mode t ? Wb. Only the decays of the Z boson to charged leptons and leptonic W-boson decays were considered as signal. Consequently, the final-state topology is characterised by the presence of three isolated charged leptons, at least two jets and missing transverse momentum from the undetected neutrino. No evidence for an FCNC signal was found. An upper limit on the t ? Zq branching ratio of BR(t ? Zq) < 0.73% is set at the 95% confidence level.

  9. Spectral probabilities of top-down tandem mass spectra

    SciTech Connect (OSTI)

    Liu, Xiaowen; Segar, Matthew W.; Li, Shuai Cheng; Kim, Sangtae

    2014-01-24T23:59:59.000Z

    In mass spectrometry (MS)-based proteomics, accurate estimation of statistical signicance of peptide and protein identications is desired for determining whether they are actually correct. Probabilistic models, such as the generating function method, have been successfully applied to compute statistical signicance of peptide-spectrum matches (PSMs) in bottom-up MS, but it is limited to PSMs of short peptides without post-translational modications (PTMs). Recently, top-down MS has be- come available in many laboratories, which often identies intact proteins with PTMs. In this paper, we propose an extended generating function (EGF) method for accurately computing statistical signicance of protein- spectrum matches (PrSMs) with PTMs.

  10. Effective field theory approach to top-quark decay at next-to-leading order in QCD

    E-Print Network [OSTI]

    Cen Zhang

    2014-05-29T23:59:59.000Z

    We present analytical results for top-quark decay processes, in an effective field theory beyond the Standard Model, at next-to-leading order in QCD. We parametrize new physics effects using dimension-six operators, and consider all operators that give rise to non-standard interactions of the top quark. We investigate both the flavor-conserving and flavor-changing decay modes, including their two-body and three-body semi-leptonic final states. The QCD mixing among relevant operators are also taken into account. These results provide all information needed for a complete model-independent study of top-quark decay at next-to-leading order accuracy, paving the way to global analyses for new physics effects in an effective field theory approach.

  11. Infrared Renormalization Group Flow for Heavy Quark Masses

    E-Print Network [OSTI]

    Andre H. Hoang; Ambar Jain; Ignazio Scimemi; Iain W. Stewart

    2008-06-17T23:59:59.000Z

    A short-distance heavy quark mass depends on two parameters, the renormalization scale mu controlling the absorption of ultraviolet fluctuations into the mass, and a scale R controlling the absorption of infrared fluctuations. 1/R can be thought of as the radius for perturbative corrections that build up the mass beyond its point-like definition in the pole scheme. Treating R as a variable gives a renormalization group equation. We argue that the sign of this anomalous dimension is universal: increasing R to add IR modes decreases m(R). The flow improves the stability of conversions between mass schemes, allowing us to avoid large logs and the renormalon. The flow in R can be used to study IR renormalons without using bubble chains, and we use it to determine the coefficient of the LambdaQCD renormalon ambiguity of the pole mass with a convergent sum-rule.

  12. Measurement of the top-quark pair-production cross section in events with two leptons and bottom-quark jets using the full CDF data set

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present a measurement of the top-quark pair production cross section in proton-antiproton collisions at ?s = 1.96??TeV. The data were collected at the Fermilab Tevatron by the CDF II detector and correspond to an ...

  13. Top-ophilia Chris Quigg

    E-Print Network [OSTI]

    Quigg, Chris

    Top-ophilia Chris Quigg Theoretical Physics Department, Fermi National Accelerator Laboratory P.O. Box 500, Batavia, Illinois 60510 USA January 11, 2008 1 Room for the Top Almost from the moment, it became clear that the top quark must exist. Exactly at what mass, we couldn't say, but we knew just how

  14. Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events from pp[over-bar] Collisions at [sqrt]s=1.96??TeV

    E-Print Network [OSTI]

    Paus, Christoph M. E.

    We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark t1) decaying to a b quark and a chargino ?1 with a subsequent ?1 decay into a neutralino ?10, ...

  15. Measurement of the W boson helicity in top quark decay at D0

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Agelou, M.; Aguilo, E.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; /Buenos Aires U. /Rio de Janeiro,

    2006-09-01T23:59:59.000Z

    The authors present a measurement of the fraction f{sub +} of right-handed W bosons produced in top quark decays, based on a candidate sample of t{bar t} events in the {ell}+jets and dilepton decay channels corresponding to an integrated luminosity of 370 pb{sup -1} collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider at {radical}s = 1.96 TeV. They reconstruct the decay angle {theta}* for each lepton. By comparing the cos{theta}* distribution from the data with those for the expected background and signal for various values of f{sub +}, they find f{sub +} = 0.056 {+-} 0.080(stat) {+-} 0.057(syst). (f{sub +} < 0.23 at 95% C.L.), consistent with the standard model prediction of f{sub +} = 3.6 x 10{sup -4}.

  16. Evidence for production of single top quarks and first direct measurement of |Vtb|

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Aguilo, E.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; /Buenos Aires U. /Rio de

    2006-12-01T23:59:59.000Z

    The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron p{bar p} collider. Using a 0.9 fb{sup -1} dataset, we apply a multivariate analysis to separate signal from background and measure {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.9 {+-} 1.4 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the CKM matrix element that describes the W tb coupling and find 0.68 < |V{sub tb}| {le} 1 at 95% C.L.

  17. Top quark three-body decays in the R-parity violating MSSM

    SciTech Connect (OSTI)

    Heng Zhaoxia; Yang Jinmin [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Academia Sinica, Beijing 100190 (China); Lu Gongru; Wu Lei [College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 (China)

    2009-05-01T23:59:59.000Z

    In the minimal supersymmetric standard model the R-parity violating interactions can trigger various exotic three-body decays for the top quark, which may be accessible at the LHC. In this work we examine the R-violating decays t{yields}cX{sub 1}X{sub 2}, which include the tree-level processes t{yields}cl{sub i}{sup -}l{sub j}{sup +} (l{sub i}=e, {mu}, {tau}) and t{yields}cd{sub i}d{sub j} (d{sub i}=d, s, b), as well as the loop-induced processes t{yields}cgX (X=g, {gamma}, Z, h). We find that the hereto weakly constrained R-violating couplings can render the decay branching ratios quite sizable, some of which already reach the sensitivity of the Tevatron collider and can be explored at the LHC with better sensitivity.

  18. Quark antiquark energies and the screening mass in a Quark-Gluon plasma at low and high temperatures

    E-Print Network [OSTI]

    O. Kaczmarek; F. Zantow

    2005-12-22T23:59:59.000Z

    We discuss quark antiquark energies and the screening mass in hot QCD using the non-perturbative lattice approach. For this purpose we analyze properties of quark antiquark energies and entropies at infinitely large separation of the quark antiquark pair at low and high temperatures. In the limit of high temperatures these energies and entropies can be related perturbatively to the temperature dependence of the Debye mass and the coupling. On the one hand our analysis thus suggests that the quark antiquark energies at (infinite) large distances are rather related to the Debye screening mass and the coupling than to the temperature dependence of heavy-light meson masses. On the other hand we find no or only little differences in all mass scales introduced by us when changing from quenched to 2-flavor QCD at temperatures which are only moderately above the phase transition.

  19. Gluon Radiation in Top Production and Decay

    E-Print Network [OSTI]

    Cosmin Macesanu; Lynne H. Orr

    2000-01-14T23:59:59.000Z

    We present the results of an exact calculation of gluon radiation in top production and decay at high energy electron-positron colliders. We include all spin correlations and interferences, the bottom quark mass, and finite top width effects in the matrix element calculation. We study properties of the radiated gluons and implications for top mass measurement.

  20. Measurement of the B+- lifetime and top quark identification using secondary vertex b-tagging

    SciTech Connect (OSTI)

    Schwartzman, Ariel G

    2004-02-01T23:59:59.000Z

    This dissertation presents a preliminary measurement of the B{sup {+-}} lifetime through the full reconstruction of its decay chain, and the identification of top quark production in the electron plus jets channel using the displaced vertex b-tagging method. Its main contribution is the development, implementation and optimization of the Kalman filter algorithm for vertex reconstruction, and of the displaced vertex technique for tagging jets arising from b quark fragmentation, both of which have now become part of the standard D0 reconstruction package. These two algorithms fully exploit the new state-of-the-art tracking detectors, recently installed as part of the Run 2 D0 upgrade project. The analysis is based on data collected during Run 2a at the Fermilab Tevatron p{bar p} Hadron Collider up to April 2003, corresponding to an integrated luminosity of 60 pb{sup -1}. The measured B meson lifetime of {tau} = 1.57 {+-} 0.18 ps is in agreement with the current world average, with a competitive level of precision expected when the full data sample becomes available.

  1. TOP AND HIGGS PHYSICS AT THE HADRON COLLIDERS

    SciTech Connect (OSTI)

    Jabeen, Shabnam

    2013-10-20T23:59:59.000Z

    This review summarizes the recent results for top quark and Higgs boson measurements from experiments at Tevatron, a protonantiproton collider at a center-of-mass energy of ? s =1 . 96 TeV, and the Large Hadron Collider, a protonproton collider at a center- of-mass energy of ? s = 7 TeV. These results include the discovery of a Higgs-like boson and measurement of its various properties, and measurements in the top quark sector, e.g. top quark mass, spin, charge asymmetry and production of single top quark.

  2. Measurements of the top quark pair production cross section and an estimate of the D0 silicon detector lifetime

    SciTech Connect (OSTI)

    Strandberg, Sara; /Stockholm U.

    2007-03-01T23:59:59.000Z

    This thesis presents two measurements of the top quark pair production cross section at {radical}s = 1:96 TeV using data from the D0 experiment. Both measurements are performed in the dilepton final state and make use of secondary vertex b-tagging.

  3. Measurement of the Inclusive Leptonic Asymmetry in Top-Quark Pairs that Decay to Two Charged Leptons at CDF

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero; et al.,

    2014-07-23T23:59:59.000Z

    We measure the inclusive forward-backward asymmetry of the charged-lepton pseudorapidities from top-quark pairs produced in proton-antiproton collisions, and decaying to final states that contain two charged leptons (electrons or muons), using data collected with the Collider Detector at Fermilab.

  4. Search for Top-Quark Partners with Charge 5/3 in the Same-Sign Dilepton Final State

    E-Print Network [OSTI]

    Apyan, Aram

    A search for the production of heavy partners of the top quark with charge 5/3 is performed in events with a pair of same-sign leptons. The data sample corresponds to an integrated luminosity of 19.5??fb[superscript ?1] ...

  5. Search for flavor changing neutral currents in top quark decays in pp collisions at 7 TeV

    E-Print Network [OSTI]

    Apyan, Aram

    The results of a search for flavor changing neutral currents in top quark decays t?Zq in events with a topology compatible with the decay chain tt?Wb+Zq???b+??q are presented. The search is performed with a data sample ...

  6. Up, down, strange and charm quark masses with Nf = 2+1+1 twisted mass lattice QCD

    E-Print Network [OSTI]

    N. Carrasco; A. Deuzeman; P. Dimopoulos; R. Frezzotti; V. Gimenez; G. Herdoiza; P. Lami; V. Lubicz; D. Palao; E. Picca; S. Recker; L. Riggio; G. C. Rossi; F. Sanfilippo; L. Scorzato; S. Simula; C. Tarantino; C. Urbach; U. Wenger

    2014-08-21T23:59:59.000Z

    We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210 - 450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI-MOM method. The results for the quark masses converted to the bar{MS} scheme are: mud(2 GeV) = 3.70(17) MeV, ms(2 GeV) = 99.6(4.3) MeV and mc(mc) = 1.348(46) GeV. We obtain also the quark mass ratios ms/mud = 26.66(32) and mc/ms = 11.62(16). By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md = 0.470(56), leading to mu = 2.36(24) MeV and md = 5.03(26) MeV.

  7. Color SU(3) symmetry, confinement, stability, clustering and quark mass dependence in the q{sup 4}q system

    SciTech Connect (OSTI)

    Dmitrasinovic, V. [Vinca Institute of Nuclear Sciences, lab 010, P.O. Box 522, 11001 Belgrade (Serbia and Montenegro)

    2006-02-01T23:59:59.000Z

    We examine the color SU(3) dynamics of q{sup 4}q system, i.e. of the pentaquark. First we study this system in the model with two-body interaction proportional to the color charges. We construct the potential matrix and show, (1) Confinement: the color singlet qq potential energy rises infinitely with the separation distance, (2) Stability: All colorless states' energies are bounded from below (3) Color singlet clustering: the pentaquark color-singlet state Hamiltonian turns into a sum of a three-quark (baryon) and a quark-antiquark (meson) cluster Hamiltonian, in the limit of asymptotically large separations. We evaluate the four excitation eigenfrequencies of pentaquarks in the harmonic oscillator two-body confining potential and the ground states' dependence on the quark-antiquark mass ratio. We show that the pentaquark is unlikely to bind even with a top antiquark, in contrast to tetraquarks.

  8. Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at $ \\sqrt{s}=8 $ TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, V. [Yerevan Physics Inst. (YerPhI) (Armenia). et al.

    2015-01-01T23:59:59.000Z

    A measurement of the W boson helicity is presented, where the W boson originates from the decay of a top quark produced in pp collisions. The event selection, optimized for reconstructing a single top quark in the final state, requires exactly one isolated lepton (muon or electron) and exactly two jets, one of which is likely to originate from the hadronization of a bottom quark. The analysis is performed using data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the CERN LHC in 2012. The data sample corresponds to an integrated luminosity of 19.7 fb$^{-1}$. The measured helicity fractions are F$_{L}$ = 0.298 0.028 (stat) 0.032(syst), F$_{0}$ = 0.720 0.039 (stat) 0.037(syst), and F$_{R}$ = -0.018 0.019 (stat) 0.011(syst). These results are used to set limits on the real part of the tWb anomalous couplings, g$_{L}$ and g$_{R}$.

  9. Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at $ \\sqrt{s}=8 $ TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, V.

    2015-01-01T23:59:59.000Z

    A measurement of the W boson helicity is presented, where the W boson originates from the decay of a top quark produced in pp collisions. The event selection, optimized for reconstructing a single top quark in the final state, requires exactly one isolated lepton (muon or electron) and exactly two jets, one of which is likely to originate from the hadronization of a bottom quark. The analysis is performed using data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the CERN LHC in 2012. The data sample corresponds to an integrated luminosity of 19.7 fb$^{-1}$.moreThe measured helicity fractions are F$_{L}$ = 0.298 0.028 (stat) 0.032(syst), F$_{0}$ = 0.720 0.039 (stat) 0.037(syst), and F$_{R}$ = -0.018 0.019 (stat) 0.011(syst). These results are used to set limits on the real part of the tWb anomalous couplings, g$_{L}$ and g$_{R}$.less

  10. Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at $ \\sqrt{s}=8 $ TeV

    SciTech Connect (OSTI)

    Khachatryan, V. [Yerevan Physics Institute (Armenia)

    2015-01-01T23:59:59.000Z

    A measurement of the W boson helicity is presented, where the W boson originates from the decay of a top quark produced in pp collisions. The event selection, optimized for reconstructing a single top quark in the final state, requires exactly one isolated lepton (muon or electron) and exactly two jets, one of which is likely to originate from the hadronization of a bottom quark. The analysis is performed using data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the CERN LHC in 2012. The data sample corresponds to an integrated luminosity of 19.7 fb$^{?1}$. The measured helicity fractions are F$_{L}$ = 0.298 0.028 (stat) 0.032(syst), F$_{0}$ = 0.720 0.039 (stat) 0.037(syst), and F$_{R}$ = ?0.018 0.019 (stat) 0.011(syst). These results are used to set limits on the real part of the tWb anomalous couplings, g$_{L}$ and g$_{R}$.

  11. QCD sum rule determination of the charm-quark mass

    SciTech Connect (OSTI)

    Bodenstein, S. [Centre for Theoretical and Mathematical Physics, University of Cape Town, Rondebosch 7700 (South Africa); Bordes, J.; Penarrocha, J. [Departamento de Fisica Teorica, Universitat de Valencia, and Instituto de Fisica Corpuscular, Centro Mixto Universitat de Valencia-CSIC (Spain); Dominguez, C. A. [Centre for Theoretical and Mathematical Physics, University of Cape Town, Rondebosch 7700 (South Africa); Department of Physics, Stellenbosch University, Stellenbosch 7600 (South Africa); Schilcher, K. [Institut fuer Physik, Johannes Gutenberg-Universitaet Staudingerweg 7, D-55099 Mainz (Germany)

    2011-04-01T23:59:59.000Z

    QCD sum rules involving mixed inverse moment integration kernels are used in order to determine the running charm-quark mass in the MS scheme. Both the high and the low energy expansion of the vector current correlator are involved in this determination. The optimal integration kernel turns out to be of the form p(s)=1-(s{sub 0}/s){sup 2}, where s{sub 0} is the onset of perturbative QCD. This kernel enhances the contribution of the well known narrow resonances, and reduces the impact of the data in the range s{approx_equal}20-25 GeV{sup 2}. This feature leads to a substantial reduction in the sensitivity of the results to changes in s{sub 0}, as well as to a much reduced impact of the experimental uncertainties in the higher resonance region. The value obtained for the charm-quark mass in the MS scheme at a scale of 3 GeV is m{sub c}(3 GeV)=987{+-}9 MeV, where the error includes all sources of uncertainties added in quadrature.

  12. Top quark forward-backward asymmetry at the Tevatron: A comparative study in different new physics models

    SciTech Connect (OSTI)

    Cao Junjie; Wu Lei [College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 (China); Heng Zhaoxia; Yang Jinmin [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Academia Sinica, Beijing 100190 (China)

    2010-01-01T23:59:59.000Z

    The top quark forward-backward asymmetry A{sub FB}{sup t} measured at the Tevatron is above the standard model prediction by more than 2{sigma} deviation, which might be a harbinger for new physics. In this work we examine the contribution to A{sub FB}{sup t} in two different new physics models: one is the minimal supersymmetric model without R parity which contributes to A{sub FB}{sup t} via sparticle-mediated t channel process dd{yields}tt; the other is the third-generation enhanced left-right model which contributes to A{sub FB}{sup t} via Z{sup '}-mediated t channel or s channel processes. We find that in the parameter space allowed by the tt production rate and the tt invariant mass distribution at the Tevatron, the left-right model can enhance A{sub FB}{sup t} to within the 2{sigma} region of the Tevatron data for the major part of the parameter space, and in optimal case A{sub FB}{sup t} can reach 12% which is slightly below the 1{sigma} lower bound. For the minimal supersymmetric model without R parity, only in a narrow part of the parameter space can the {lambda}{sup ''} couplings enhance A{sub FB}{sup t} to within the 2{sigma} region while the {lambda}{sup '} couplings just produce negative contributions to worsen the fit.

  13. Model-independent measurement of $\\boldsymbol{t}$-channel single top quark production in $\\boldsymbol{p\\bar{p}}$ collisions at $\\boldsymbol{\\sqrt{s}=1.96}$ TeV

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls; Alverson, George O.; /Northeastern U.; Alves, Gilvan Augusto; /Rio de Janeiro, CBPF; Ancu, Lucian Stefan; /Nijmegen U. /Fermilab

    2011-05-01T23:59:59.000Z

    We present a model-independent measurement of t-channel electroweak production of single top quarks in p{bar p} collisions at {radical}s = 1.96 TeV. Using 5.4 fb{sup -1} of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider, and selecting events containing an isolated electron or muon, missing transverse energy and one or two jets originating from the fragmentation of b quarks, we measure a cross section {sigma}(p{bar p} {yields} tqb + X) = 2.90 {+-} 0.59 (stat + syst) pb for a top quark mass of 172.5 GeV. The probability of the background to fluctuate and produce a signal as large as the one observed is 1.6 x 10{sup -8}, corresponding to a significance of 5.5 standard deviations.

  14. First measurement of top quark pair production cross-section in muon plus hadronic tau final states

    SciTech Connect (OSTI)

    Sumowidagdo, Suharyo; /Florida State U.

    2007-11-01T23:59:59.000Z

    This dissertation presents the first measurement of top quark pair production cross-section in events containing a muon and a tau lepton. The measurement was done with 1 fb{sup -1} of data collected during April 2002 through February 2006 using the D0 detector at the Tevatron proton-antiproton collider, located at Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois. Events containing one isolated muon, one tau which decays hadronically, missing transverse energy, and two or more jets (at least one of which must be tagged as a heavy flavor jet) were selected. Twenty-nine candidate events were observed with an expected background of 9.16 events. The top quark pair production cross-section is measured to be {sigma}(t{bar t}) = 8.0{sub -2.4}{sup +2.8}(stat){sub -1.7}{sup +1.8}(syst) {+-} 0.5(lumi) pb. Assuming a top quark pair production cross-section of 6.77 pb for Monte Carlo signal top events without a real tau, the measured {sigma} x BR is {sigma}(t{bar t}) x BR(t{bar t} {yields} {mu} + {tau} + 2{nu} + 2b) = 0.18{sub -0.11}{sup +0.13}(stat){sub -0.09}{sup +0.09}(syst) {+-} 0.01(lumi) pb.

  15. A Method for the Precision Mass Measurement of the Stop Quark at the International Linear Collider

    SciTech Connect (OSTI)

    Freitas, Ayres; /Chicago U. /Argonne /Zurich U.; Milstene, Caroline; /Fermilab /Wayne State U.; Schmitt, Michael; /Northwestern U.; Sopczak, Andre; /Lancaster U.

    2008-06-01T23:59:59.000Z

    Many supersymmetric models predict new particles within the reach of the next generation of colliders. For an understanding of the model structure and the mechanism(s) of symmetry breaking, it is important to know the masses of the new particles precisely. In this article the measurement of the mass of the scalar partner of the top quark (stop) at an e+e- collider is studied. A relatively light stop is motivated by attempts to explain electroweak baryogenesis and can play an important role in dark matter relic density. A method is presented which makes use of cross-section measurements near the pair-production threshold as well as at higher center-of-mass energies. It is shown that this method not only increases the statistical precision, but also greatly reduces the systematic uncertainties, which can be important. Numerical results are presented, based on a realistic event simulation, for two signal selection strategies: using conventional selection cuts, and using an Iterative Discriminant Analysis (IDA). Our studies indicate that a precision of {Delta}m{tilde t}{sub 1} = 0.42 GeV can be achieved, representing a major improvement over previous studies. While the analysis of stops is particularly challenging due to the possibility of stop hadronization, the general procedure could be applied to the mass measurement of other particles as well. We also comment on the potential of the IDA to discover a stop quark in this scenario, and we revisit the accuracy of the theoretical predictions for the neutralino relic density

  16. Charm and strange quark masses and $f_{D_s}$ from overlap fermions

    E-Print Network [OSTI]

    Yi-Bo Yang; Ying Chen; Andrei Alexandru; Shao-Jing Dong; Terrence Draper; Ming Gong; Frank X. Lee; Anyi Li; Keh-Fei Liu; Zhaofeng Liu; Michael Lujan

    2015-05-18T23:59:59.000Z

    We use overlap fermions as valence quarks to calculate meson masses in a wide quark mass range on the $2+1$-flavor domain-wall fermion gauge configurations generated by the RBC and UKQCD Collaborations. The well-defined quark masses in the overlap fermion formalism and the clear valence quark mass dependence of meson masses observed from the calculation facilitate a direct derivation of physical current quark masses through a global fit to the lattice data, which incorporates $O(a^2)$ and $O(m_c^4a^4)$ correction, linear chiral extrapolation, and quark mass interpolation. Using the physical masses of $D_s$, $D_s^*$ and $J/\\psi$ as inputs, Sommer's scale parameter $r_0$ and the masses of charm quark and strange quark in the $\\overline{\\rm MS}$ scheme are determined to be $r_0=0.465(4)(9)$ fm, $m_c^{\\overline{\\rm MS}}(2\\,{\\rm GeV})=1.118(6)(23)$ GeV (or $m_c^{\\overline{\\rm MS}}(m_c)=1.304(5)(19)$ GeV), and $m_s^{\\overline{\\rm MS}}(2\\,{\\rm GeV})=0.101(3)(5)\\,{\\rm GeV}$, respectively. Furthermore, we observe that the mass difference of the vector meson and the pseudoscalar meson with the same valence quark contents is proportional to the reciprocal of the square root of the valence quark masses. The hyperfine splitting of charmonium, $M_{J/\\psi}-M_{\\eta_c}$, is determined to be 119(2)(6) MeV, which is in good agreement with the experimental value. We also predict the decay constant of $D_s$ to be $f_{D_s}=254(2)(4)$ MeV. The masses of charmonium $P$-wave states $\\chi_{c0}, \\chi_{c1}$ and $h_c$ are also in good agreement with experiments.

  17. R-parity violating effects in top quark flavor-changing neutral-current production at LHC

    SciTech Connect (OSTI)

    Cao Junjie [College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 (China); Ottawa-Carleton Institute for Physics, Carleton University, Ottawa, K1S 5B6 (Canada); Heng Zhaoxia; Yang Jinmin [Institute of Theoretical Physics and Kavli Institute for Theoretical Physics China, Academia Sinica, Beijing 100190 (China); Wu Lei [College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007 (China)

    2009-03-01T23:59:59.000Z

    In the minimal supersymmetric model the R-parity violating top quark interactions, which are so far weakly constrained, can induce various flavor-changing neutral-current (FCNC) productions for the top quark at the large hadron collider (LHC). In this work we assume the presence of the B-violating couplings and examine their contributions to the FCNC productions proceeding through the parton processes cg{yields}t, gg{yields}tc, cg{yields}t{gamma}, cg{yields}tZ and cg{yields}th. We find that all these processes can be greatly enhanced relative to the R-parity preserving predictions. In the parameter space allowed by current experiments, all the production channels except cg{yields}th can reach the 3{sigma} sensitivity, in contrast to the R-parity preserving case in which only cg{yields}t can reach the 3{sigma} sensitivity.

  18. Direct Bound on the Total Decay Width of the Top Quark in pp? Collisions at ?s=1.96??TeV

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present the first direct experimental bound on the total decay width of the top quark, ?[subscript t], using 955??pb[superscript -1] of the Tevatrons pp? collisions recorded by the Collider Detector at Fermilab. We ...

  19. Measurements of t[bar over t] Spin Correlations and Top-Quark Polarization Using Dilepton Final States in pp Collisions at ?s = 7 TEV

    E-Print Network [OSTI]

    Apyan, Aram

    Spin correlations and polarization in the top quarkantiquark system are measured using dilepton final states produced in pp collisions at the LHC at ?s = 7??TeV. The data correspond to an integrated luminosity of ...

  20. Search for resonant top quark plus jet production in tt? +jets events with the ATLAS detector in pp collisions at ?s=7??TeV

    E-Print Network [OSTI]

    Taylor, Frank E.

    This paper presents a search for a new heavy particle produced in association with a top or antitop quark. Two models in which the new heavy particle is a color singlet or a color triplet are considered, decaying, respectively, ...

  1. Infrared and Ultraviolet QCD dynamics with quark mass for J=0,1 mesons

    E-Print Network [OSTI]

    Nicholas Souchlas

    2010-06-04T23:59:59.000Z

    By using a previously developed phenomenological kernel for the study of the light quark QCD sector and dynamical chiral symmetry breaking effects we will examine the relative infrared and ultraviolet QCD dynamics for J=0,1 meson properties. For the same reasons we extend and explore a quark mass depended generalization of the kernel in the heavy quark region and we also compare with the original model. The relation between the dynamics of the quark propagator and the effective kernel with the J=0,1 QQ and qQ mesons and quarks Compton size is also discussed.

  2. Measurement of W-Boson Polarization in Top-quark Decay in ppbar Collisions at sqrt(s) = 1.96 TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

    2010-03-01T23:59:59.000Z

    We report measurements of the polarization of W bosons from top-quark decays using 2.7 fb{sup -1} of p{bar p} collisions collected by the CDF II detector. Assuming a top-quark mass of 175 GeV/c{sup 2}, three measurements are performed. A simultaneous measurement of the fraction of longitudinal (f{sub 0}) and right-handed (f{sub +}) W bosons yields the model-independent results f{sub 0} = 0.88 {+-} 0.11(stat) {+-} 0.06(syst) and f{sub +} = -0.15 {+-} 0.07(stat) {+-} 0.06(syst) with a correlation coefficient of -0.59. A measurement of f{sub 0} (f{sub +}) constraining f{sub +} (f{sub 0}) to its standard model value of 0.0 (0.7) yields f{sub 0} = 0.70 {+-} 0.07(stat) {+-} 0.04(syst) (f{sub +} = 0.01 {+-} 0.02(stat) {+-} 0.05(syst)). All these results are consistent with standard model expectations.

  3. Uncertainties in Estimating the Indirect Production of $B_c$ and Its Excited States Via Top Quark Decays at CERN LHC

    E-Print Network [OSTI]

    Xing-Gang Wu

    2008-12-08T23:59:59.000Z

    Main theoretical uncertainties in estimating the indirect production of $(b\\bar{c})$-quarkonium ($B^-_c$ meson and its excited states) via top quark decays, $t\\to (b\\bar{c})+c+W^{+}$, are studied within the non-relativistic QCD framework. It is found that the dimensionless reduced decay width for a particular $(b\\bar{c})$-quarkonium state, $\\bar\\Gamma_{n}=\\Gamma_{n} /\\Gamma_{t\\to W^{+}+b}$, is very sensitive to the $c$-quark mass, while the uncertainties from the $b$-quark and $t$-quark masses are small, where $n$ stands for the eight $(b\\bar{c})$-quarkonium states up to ${\\cal O}(v^4)$: $|(b\\bar{c})(^1S_0)_1>$, $|(b\\bar{c})(^3S_1)_1>$, $|(b\\bar{c})(^1P_1)_1>$, $|(b\\bar{c})(^3P_J)_1>$ (with $J=(1,2,3)$), $|(b\\bar{c})(^1S_0)_{8}g>$ and $|(b\\bar{c})(^3S_1)_{8}g>$ respectively. About $10^8$ $t\\bar{t}$-pairs shall be produced per year at CERN LHC, if adopting the assumption that all the higher Fock states decay to the ground state with 100% probability, then we shall have $(1.038^{+1.353}_{-0.782})\\times 10^5$ $B^-_c $ events per year. So the indirect production provides another important way to study the properties of $B^-_c$ meson in comparison to that of the direct hadronic production at CERN LHC.

  4. Seeking Texture Zeros in the Quark Mass Matrix Sector of the Standard Model

    E-Print Network [OSTI]

    Giraldo, Yithsbey

    2015-01-01T23:59:59.000Z

    Here we show that the Weak Basis Transformation is an appropriate mathematical tool that can be used to find texture zeros in the quark mass matrix sector of the Standard Model. So, starting with the most general quark mass matrices and taking physical data into consideration, is possible to obtain more than three texture zeros by any weak basis transformation. Where the most general quark mass matrices considered in the model, were obtained through a special weak basis wherein the mass matrix $M_u$~(or $M_d$) has been taken to be diagonal and only the matrix $M_d$~(or $M_u$) is considered to be most general.

  5. Measurement of R = B(t?Wb)/B(t?Wq) in top-quark-pair decays using lepton+jets events and the full CDF run II dataset

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We present a measurement of the ratio of the top-quark branching fractions R=B(t?Wb)/ B(t?Wq), where q represents quarks of type b, s, or d, in the final state with a lepton and hadronic jets. The measurement uses ?s=1.96??TeV ...

  6. O(?_s^2) corrections to the running top-Yukawa coupling and the mass of the lightest Higgs boson in the MSSM

    E-Print Network [OSTI]

    D. Kunz; L. Mihaila; N. Zerf

    2014-12-17T23:59:59.000Z

    In this paper we propose a method to compute the running top-Yukawa coupling in supersymmetric models with heavy mass spectrum based on the "running" and "decoupling" procedure. In order to enable this approach we compute the two-loop SUSY-QCD radiative corrections required in the decoupling process. The method has the advantage that large logarithmic corrections are automatically resummed through the Renormalization Group Equations. As phenomenological application we study the effects of this approach on the prediction of the lightest Higgs boson mass at three-loop accuracy. We observe a significant reduction of the renormalization scale dependence as compared to the direct method, that is based on the conversion relation between the running and pole mass for the top quark. The effect of resummation of large logarithmic contributions consists in an increased prediction for the Higgs boson mass, an observation in agreement with the previous analyses.

  7. Top-quark production in proton-nucleus and nucleus-nucleus collisions at LHC energies and beyond

    E-Print Network [OSTI]

    David d'Enterria; Krisztian Krajczar; Hannu Paukkunen

    2015-04-21T23:59:59.000Z

    Single and pair top-quark production in proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions at the CERN Large Hadron Collider (LHC) and future circular collider (FCC) energies, are studied with next-to-leading-order perturbative QCD calculations including nuclear parton distribution functions. At the LHC, the pair-production cross sections amount to sigma(t-tbar) = 3.4 mub in Pb-Pb at sqrt(s) = 5.5 TeV, and sigma(t-tbar) = 60 nb in p-Pb at sqrt(s) = 8.8 TeV. At the FCC energies of sqrt(s) = 39 and 63 TeV, the same cross sections are factors of 90 and 55 times larger respectively. In the leptonic final-state t-tbar --> W+b W-bbar --> b bbar l+l- nu+nu-, after typical acceptance and efficiency cuts, one expects about 90 and 300 top-quarks per nominal LHC-year and 4.7 10^4 and 10^5 per FCC-year in Pb-Pb and p-Pb collisions respectively. The total t-tbar cross sections, dominated by gluon fusion processes, are enhanced by 3--8% in nuclear compared to p-p collisions due to an overall net gluon antishadowing, although different regions of their differential distributions are depleted due to shadowing or EMC-effect corrections. The rapidity distributions of the decay leptons in t-tbar processes can be used to reduce the uncertainty on the Pb gluon density at high virtualities by up to 30% at the LHC (full heavy-ion programme), and by 70% per FCC-year. The cross sections for single-top production in electroweak processes are also computed, yielding about a factor of 30 smaller number of measurable top-quarks after cuts, per system and per year.

  8. Top-quark production in proton-nucleus and nucleus-nucleus collisions at LHC energies and beyond

    E-Print Network [OSTI]

    David d'Enterria; Krisztian Krajczar; Hannu Paukkunen

    2015-01-23T23:59:59.000Z

    Single and pair top-quark production in proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions at the CERN Large Hadron Collider (LHC) and future circular collider (FCC) energies, are studied with next-to-leading-order perturbative QCD calculations including nuclear parton distribution functions. At the LHC, the pair-production cross sections amount to sigma(t-tbar) = 3.4 mub in Pb-Pb at sqrt(s) = 5.5 TeV, and sigma(t-tbar) = 60 nb in p-Pb at sqrt(s) = 8.8 TeV. At the FCC energies of sqrt(s) = 39 and 63 TeV, the same cross sections are factors of 90 and 55 times larger respectively. In the leptonic final-state t-tbar --> W+b W-bbar --> b bbar l+l- nu+nu-, after typical acceptance and efficiency cuts, one expects about 90 and 300 top-quarks per nominal LHC-year and 4.7 10^4 and 10^5 per FCC-year in Pb-Pb and p-Pb collisions respectively. The total t-tbar cross sections, dominated by gluon fusion processes, are enhanced by 3--8% in nuclear compared to p-p collisions due to an overall net gluon antishadowing, although different regions of their differential distributions are depleted due to shadowing or EMC-effect corrections. The rapidity distributions of the decay leptons in t-tbar processes can be used to reduce the uncertainty on the Pb gluon density at high virtualities by up to 30% at the LHC (full heavy-ion programme), and by 70% per FCC-year. The cross sections for single-top production in electroweak processes are also computed, yielding about a factor of 30 smaller number of measurable top-quarks after cuts, per system and per year.

  9. Search for Scalar Top Quark Pair-Production in Scenario with Violated R-parity in ppbar Collisions at sqrt(s)=1.96 TeV

    SciTech Connect (OSTI)

    Ogawa, Takashi

    2005-01-01T23:59:59.000Z

    A search for the pair production of supersymmetric partner of the top quark in scenario with R-parity violation is presented. The quantum number called R-parity distinguishes particles in standard model from supersymmetric particles. A scalar top quark (stop) is assumed to decay only via R{sub p}-violating supersymmetric coupling into tau lepton and b-quark. To collect events with multiple taus, a new special tau trigger (the lepton plus track trigger) is installed in Run II experiment of the Collider Detector at Fermilab (CDF). The goal of the lepton plus track trigger is to collect generic dilepton ({ell}{ell}, {ell}{tau}, {tau}{tau}) events with lower p{sub T} threshold (8 GeV/c) and without prescale even at high luminosity. The Z {yields} {tau}{tau} event, where one {tau}-lepton decays leptonically and the other hadronically, is a good benchmark to calibrate the lepton plus track trigger and {tau} identification. The data sample of 72 pb{sup -1}, collected using the electron plus track trigger, contains clear a {tau} signal from Z {yields} {tau}{tau} events. The data used in stop search correspond to 200 pb{sup -1}. The lower stop mass bound of 134 GeV/c{sup 2} at a 95% confidence level is obtained. This limit is also directly applicable to the case of the third generation scalar leptoquark (LQ{sub 3}) assuming a 100% branching for the LQ{sub 3} {yields} {tau}b decay mode.

  10. Search for H to $ \\mathrm{b\\bar{b}}$ in association with single top quarks as a test of Higgs boson couplings

    E-Print Network [OSTI]

    Simon Fink

    2015-03-18T23:59:59.000Z

    The production of a Higgs boson in association with a single top quark is one of a few channels which are sensitive for not yet excluded anomalous couplings of the Higgs boson to fermions. Multivariate analysis tools are used for the reconstruction and classification of signal events, where the Higgs boson decays into bottom quarks and the single top quark decays leptonically. In this conference report the most recent results at time of the conference using the full dataset recorded by the CMS detector at 8 TeV are presented.

  11. Search for t-Channel Single Top Quark Production in p anti-p Collisions at 1.96 TeV

    SciTech Connect (OSTI)

    Perea, Philip Michael

    2006-06-01T23:59:59.000Z

    I have performed a search for t-channel single top quark production in p{bar p} collisions at 1.96 TeV on a 366 pb{sup -1} dataset collected with the D0 detector from 2002-2005. The analysis is restricted to the leptonic decay of the W boson from the top quark to an electron or muon, tq{bar b} {yields} lv{sub l}b q{bar b} (l = e,{mu}). A powerful b-quark tagging algorithm derived from neural networks is used to identify b jets and significantly reduce background. I further use neural networks to discriminate signal from background, and apply a binned likelihood calculation to the neural network output distributions to derive the final limits. No direct observation of single top quark production has been made, and I report expected/measured 95% confidence level limits of 3.5/8.0 pb.

  12. Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp? Collisions at ?s = 1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T; Gonzalez, B Alvarez; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; et al

    2011-07-11T23:59:59.000Z

    We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t?Hb ? W(*)a10b, and subsequently decaying into ?+?-. Using a data sample corresponding to an integrated luminosity of 2.7 fb-1 collected by the CDF II detector in pp? collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t?Hb formorevarious masses of H and a10.less

  13. Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp? Collisions at ?s = 1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T [Helsinki Inst. of Phys.; Gonzalez, B Alvarez [Oviedo U.; Cantabria Inst. of Phys.; Amerio, S [INFN, Padua; Amidei, D [Michigan U.; Anastassov, A [Northwestern U.; Annovi, A [Frascati; Antos, J [Comenius U.; Apollinari, G [Fermilab; Appel, J A [Fermilab; Apresyan, A [Purdue U.; Arisawa, T [Waseda U.; Dubna, JINR

    2011-07-11T23:59:59.000Z

    We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t?Hb ? W(*)a10b, and subsequently decaying into ?+?-. Using a data sample corresponding to an integrated luminosity of 2.7 fb-1 collected by the CDF II detector in pp? collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t?Hb for various masses of H and a10.

  14. Automatic computations at next-to-leading order in QCD for top-quark flavor-changing neutral processes

    E-Print Network [OSTI]

    Celine Degrande; Fabio Maltoni; Jian Wang; Cen Zhang

    2015-03-02T23:59:59.000Z

    Computations at next-to-leading order in the Standard Model offer new technical challenges in presence of higher dimensional operators. We introduce a framework that, starting from the top-quark effective field theory at dimension six, allows to make predictions for cross sections as well as distributions in a fully automatic way. As an application, we present the first complete results at NLO in QCD for flavor changing neutral interactions including parton shower effects, for $tZ$, $th$, $t\\gamma$ associated production at the LHC.

  15. Constraining a fourth generation of quarks: non-perturbative Higgs boson mass bounds

    E-Print Network [OSTI]

    John Bulava; Karl Jansen; Attila Nagy

    2013-01-15T23:59:59.000Z

    We present a non-perturbative determination of the upper and lower Higgs boson mass bounds with a heavy fourth generation of quarks from numerical lattice computations in a chirally symmetric Higgs-Yukawa model. We find that the upper bound only moderately rises with the quark mass while the lower bound increases significantly, providing additional constraints on the existence of a straight-forward fourth quark generation. We examine the stability of the lower bound under the addition of a higher dimensional operator to the scalar field potential using perturbation theory, demonstrating that it is not significantly altered for small values of the coupling of this operator. For a Higgs boson mass of $\\sim125\\mathrm{GeV}$ we find that the maximum value of the fourth generation quark mass is $\\sim300\\mathrm{GeV}$, which is already in conflict with bounds from direct searches.

  16. Bound Energy Masses of Mesons Containing the Fourth Generation and Iso-singlet Quarks

    E-Print Network [OSTI]

    Sameer M. Ikhdair; Ramazan Sever

    2005-07-18T23:59:59.000Z

    The fourth Standard Model (SM) family quarks and weak iso-singlet quarks The fourth Standard Model (SM) family quarks and weak iso-singlet quarks predicted by ${\\rm E}_{6\\text{}}$ GUT are considered. The spin-average of the pseudoscalar $\\eta_{4}(n^{1}S_{0})$ and vector $\\psi_{4}(n^{3}S_{1})$ quarkonium binding masses of the new mesons formed by the fourth Standard Model (SM) family and iso-singlet ${\\rm E}_{6\\text{}}$ with their mixings to ordinary quarks are investigated. Further, the fine and hyperfine mass splittings of the these states are also calculated. We solved the Schr\\"{o}dinger equation with logarithmic and Martin potentials using the Shifted large-${\\rm N}$ expansion technique. Our results are compared with other models to gauge the reliability of the predictions and point out differences.

  17. Physics of top

    E-Print Network [OSTI]

    C. -P. Yuan

    2006-04-24T23:59:59.000Z

    I will briefly review the physics of top quark at high energy colliders. A new discovery of single-top event at the Fermilab Tevatron is expected. At the CERN Large Hadron Collider, detailed top quark properties can be measured and new physics ideas in which top quark plays a special role can be tested. I will also discuss a few phenomenological methods for analyzing experimental data to study top quark interactions.

  18. Updated values of running quark and lepton masses at GUT scale in SM, 2HDM and MSSM

    E-Print Network [OSTI]

    Kalpana Bora

    2012-06-26T23:59:59.000Z

    Updated values of running quark and lepton masses at GUT (Grand unified theories) scales are important for fermion mass model building, and to calculate neutrino masses, in GUTs . We present their values at GUT scales, in SM, MSSM and 2HDM theories, using the latest values of running quark and lepton masses.

  19. Texture Zero Mass Matrices and Flavor Mixing of Quarks and Leptons

    E-Print Network [OSTI]

    Fritzsch, Harald

    2015-01-01T23:59:59.000Z

    We discuss mass matrices with four texture zeros for the quarks and leptons. The three mixing angles for the quarks and leptons are functions of the fermion masses. The results agree with the experimental data. The ratio of the masses of the first two neutrinos is given by the solar mixing angle. The neutrino masses are calculated: $m_1$ $\\approx$ 0.003 eV , $m_2$ $\\approx$ 0.012 eV , $m_3$ $\\approx$ 0.048 eV.

  20. Top-quark production in proton-nucleus and nucleus-nucleus collisions at LHC energies and beyond

    E-Print Network [OSTI]

    d'Enterria, David; Paukkunen, Hannu

    2015-01-01T23:59:59.000Z

    Single and pair top-quark production in proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions at the CERN Large Hadron Collider (LHC) and future circular collider (FCC) energies, are studied with next-to-leading-order perturbative QCD calculations including nuclear parton distribution functions. At the LHC, the pair-production cross sections amount to sigma(t-tbar) = 3.4 mub in Pb-Pb at sqrt(s) = 5.5 TeV, and sigma(t-tbar) = 60 nb in p-Pb at sqrt(s) = 8.8 TeV. At the FCC energies of sqrt(s) = 39 and 63 TeV, the same cross sections are factors of 90 and 55 times larger respectively. In the leptonic final-state t-tbar --> W+b W-bbar --> b bbar l+l- nu+nu-, after typical acceptance and efficiency cuts, one expects about 90 and 300 top-quarks per nominal LHC-year and 4.7 10^4 and 10^5 per FCC-year in Pb-Pb and p-Pb collisions respectively. The total t-tbar cross sections, dominated by gluon fusion processes, are enhanced by 3--8% in nuclear compared to p-p collisions due to an overall net gluon antishadowing, altho...

  1. Theoretical overview on top pair production and single top production

    E-Print Network [OSTI]

    Stefan Weinzierl

    2012-01-19T23:59:59.000Z

    In this talk I will give an overview on theoretical aspects of top quark physics. The focus lies on top pair production and single top production.

  2. Top physics results from CDF

    SciTech Connect (OSTI)

    Gomez, Gervasio; /Cantabria Inst. of Phys.

    2005-05-01T23:59:59.000Z

    The top quark is by far the most massive fundamental particle observed so far, and the study of its properties is interesting for several reasons ranging from its possible special role in electroweak symmetry breaking to its sensitivity to physics beyond the Standard Model. They present recent top physics results from CDF based on 160-320 pb{sup -1} of p{bar p} collision data at {radical}s = 1.96 TeV. The t{bar t} cross section and the top mass have been measured in different decay channels and using different methods. they have searched for evidence of single top production, setting upper limits on its production rate. Other results shown in this conference include studies of the polarization of W bosons from top decays, a search for charged Higgs decaying from top, and a search for additional heavy t' quarks.

  3. Top pair production at a future $e^+e^-$ machine in a composite Higgs scenario

    E-Print Network [OSTI]

    Daniele Barducci; Stefania De Curtis; Stefano Moretti; Giovanni Marco Pruna

    2015-04-21T23:59:59.000Z

    The top quark plays a central role in many New Physics scenarios and in understanding the details of Electro-Weak Symmetry Breaking. In the short- and mid-term future, top-quark studies will mainly be driven by the experiments at the Large Hadron Collider. Exploration of top quarks will, however, be an integral part of particle physics studies at any future facility and an $e^+ e^-$ collider will have a very comprehensive top-quark physics program. We discuss the possibilities of testing NP in the top-quark sector within a composite Higgs scenario through deviations from the Standard Model in top pair production for different Centre-of-Mass energy options of a future $e^+e^-$ machine. In particular, we focus on precision studies of the top-quark sector at a CM energy ranging from 370 GeV up to 3 TeV.

  4. Top pair production at a future $e^+e^-$ machine in a composite Higgs scenario

    E-Print Network [OSTI]

    Barducci, Daniele; Moretti, Stefano; Pruna, Giovanni Marco

    2015-01-01T23:59:59.000Z

    The top quark plays a central role in many New Physics scenarios and in understanding the details of Electro-Weak Symmetry Breaking. In the short- and mid-term future, top-quark studies will mainly be driven by the experiments at the Large Hadron Collider. Exploration of top quarks will, however, be an integral part of particle physics studies at any future facility and an $e^+ e^-$ collider will have a very comprehensive top-quark physics program. We discuss the possibilities of testing NP in the top-quark sector within a composite Higgs scenario through deviations from the Standard Model in top pair production for different Centre-of-Mass energy options of a future $e^+e^-$ machine. In particular, we focus on precision studies of the top-quark sector at a CM energy ranging from 370 GeV up to 3 TeV.

  5. Search for charged Higgs bosons decaying via H+ -> tau nu in top quark pair events using pp collision data at sqrt(s) = 7 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, Georges; Abbott, Brad; Abdallah, Jalal; Abdel Khalek, Samah; Abdelalim, Ahmed Ali; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; /SUNY, Albany /Alberta U. /Ankara U. /Dumlupinar U. /Gazi U. /TOBB ETU, Ankara /TAEK, Ankara /Annecy, LAPP /Argonne /Arizona U. /Texas U., Arlington

    2012-04-01T23:59:59.000Z

    The results of a search for charged Higgs bosons are presented. The analysis is based on 4.6 fb{sup -1} of proton-proton collision data at {radical}s = 7 TeV collected by the ATLAS experiment at the Large Hadron Collider, using top quark pair events with a {tau} lepton in the final state. The data are consistent with the expected background from Standard Model processes. Assuming that the branching ratio of the charged Higgs boson to a {tau} lepton and a neutrino is 100%, this leads to upper limits on the branching ratio of top quark decays to a b quark and a charged Higgs boson between 5% and 1% for charged Higgs boson masses ranging from 90 GeV to 160 GeV, respectively. In the context of the m{sub h}{sup max} scenario of the MSSM, tan {beta} above 12-26, as well as between 1 and 2-6, can be excluded for charged Higgs boson masses between 90 GeV and 150 GeV.

  6. Radiative Generation of Quark Masses and Mixing Angles in the Two Higgs Doublet Model

    E-Print Network [OSTI]

    Alejandro Ibarra; Ana Solaguren-Beascoa

    2014-07-04T23:59:59.000Z

    We present a framework to generate the quark mass hierarchies and mixing angles by extending the Standard Model with one extra Higgs doublet. The charm and strange quark masses are generated by small quantum effects, thus explaining the hierarchy between the second and third generation quark masses. All the mixing angles are also generated by small quantum effects: the Cabibbo angle is generated at zero-th order in perturbation theory, while the remaining off-diagonal entries of the Cabibbo-Kobayashi-Maskawa matrix are generated at first order, hence explaining the observed hierarchy $|V_{ub}|,|V_{cb}|\\ll |V_{us}|$. The values of the radiatively generated parameters depend only logarithmically on the heavy Higgs mass, therefore this framework can be reconciled with the stringent limits on flavor violation by postulating a sufficiently large new physics scale.

  7. Light quark masses, chiral condensate and quark-gluon condensate in quenched lattice QCD with exact chiral symmetry

    E-Print Network [OSTI]

    Chiu, T W; Chiu, Ting-Wai; Hsieh, Tung-Han

    2003-01-01T23:59:59.000Z

    We determine several quantities in quenched lattice QCD with exact chiral symmetry. For 100 gauge configurations generated with Wilson gauge action at $ \\beta = 6.0 $ on the $ 16^3 \\times 32 $ lattice, we compute quenched quark propagators for 13 bare quark masses. The pion decay constant is extracted from the pion propagator, and from which the inverse lattice spacing is determined to be $ a^{-1} = 1.979(6) $ GeV. The parameters ($ C, \\delta, B $) in the pseudoscalar meson mass formula in quenched chiral perturbation theory (q$\\chi$PT) to one-loop order are determined. Further, we measure the index (topological) susceptibility of these 100 gauge configurations, $ \\chi_t = (175 \\pm 6 {MeV})^4 $, from which we obtain an estimate of the mass of $ \\eta' $ in q$\\chi$PT, and the coefficient of quenched chiral logarithm, both in good agreement with the values determined from the pion masses, as well as with the theoretical estimates. With our values of $ C, \\delta, B $, the experimental inputs of pion and kaon mass...

  8. TOP 2014: Experimental Summary

    E-Print Network [OSTI]

    Christian Schwanenberger

    2015-03-05T23:59:59.000Z

    A summary of the experimental results of the TOP2014 International Workshop in Cannes, France, is presented. This inspiring conference clearly showed the richness and diversity of top-quark physics research. Results cover a very broad spectrum of analyses involving studies of the strong and electroweak interactions of the top quark, high-precision measurements of intrinsic top-quark properties, developments of new tools in top-quark analyses, observations of new Standard Model processes, the interaction between the top quark and the Higgs boson and sensitive searches for new physics beyond the Standard Model.

  9. Measurement of the Differential Cross Section d?/d(cos??[subscript t]) for Top-Quark Pair Production in p[bar over p] Collisions at ?s = 1.96??TeV

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    We report a measurement of the differential cross section d?/d(cos?[subscript t]) for top-quark pair production as a function of the top-quark production angle in proton-antiproton collisions at s? = 1.96??TeV. This ...

  10. Measurement of the W boson helicity in top quark decays using 5.4 fb? of pp? collision data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; et al

    2011-02-01T23:59:59.000Z

    We present a measurement of the helicity of the W boson produced in top quark decays using tt decays in the l+jets and dilepton final states selected from a sample of 5.4 fb? of collisions recorded using the D0 detector at the Fermilab Tevatron pp? collider. We measure the fractions of longitudinal and right-handed W bosons to be f?=0.6690.102[0.078(stat.)0.065(syst.)] and f?=0.0230.053[0.041(stat.)0.034(syst.)], respectively. This result is consistent at the 98% level with the standard model. A measurement with f? fixed to the value from the standard model yields f?=0.0100.037[0.022(stat.)0.030(syst.)].

  11. Measurement of the W boson helicity in top quark decays using 5.4 fb? of pp? collision data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Ancu, L. S.; Aoki, M.; Arnoud, Y.; Arov, M.; Askew, A.; sman, B.; Atramentov, O.; Avila, C.; BackusMayes, J.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Beale, S.; Bean, A.; Begalli, M.; Begel, M.; Belanger-Champagne, C.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besanon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Bolton, T. A.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burnett, T. H.; Buszello, C. P.; Calpas, B.; Camacho-Prez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thry, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Christoudias, T.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Croc, A.; Cutts, D.; ?wiok, M.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Dliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Dominguez, A.; Dorland, T.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Gadfort, T.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; Geist, W.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grnendahl, S.; Grnewald, M. W.; Guo, F.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hossain, S.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffr, M.; Jain, S.; Jamin, D.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Khatidze, D.; Kirby, M. H.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kur?a, T.; Kuzmin, V. A.; Kvita, J.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, Y.; Liu, Z.; Lobodenko, A.; Lokajicek, M.; Love, P.; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magaa-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martnez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Mondal, N. K.; Muanza, G. S.; Mulhearn, M.; Nagy, E.; Naimuddin, M.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Novaes, S. F.; Nunnemann, T.; Obrant, G.; Orduna, J.; Osman, N.; Osta, J.; Otero y Garzn, G. J.; Owen, M.; Padilla, M.; Pangilinan, M.; Parashar, N.; Parihar, V.; Park, S. K.; Parsons, J.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, K.; Peters, Y.; Petrillo, G.; Ptroff, P.; Piegaia, R.; Piper, J.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V.M.; Pol, M.-E.; Polozov, P.; Popov, A. V.; Prewitt, M.; Price, D.; Protopopescu, S.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M. S.; Ranjan, K.; Ratoff, P. N.; Razumov, I.; Renkel, P.; Rich, P.; Rijssenbeek, M.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Royon, C.; Rubinov, P.; Ruchti, R.; Safronov, G.; Sajot, G.; Snchez-Hernndez, A.; Sanders, M. P.; Sanghi, B.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schliephake, T.; Schlobohm, S.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shchukin, A. A.; Shivpuri, R. K.; Simak, V.; Sirotenko, V.; Skubic, P.; Slattery, P.; Smirnov, D.

    2011-02-01T23:59:59.000Z

    We present a measurement of the helicity of the W boson produced in top quark decays using tt decays in the ?+jets and dilepton final states selected from a sample of 5.4??fb? of collisions recorded using the D0 detector at the Fermilab Tevatron pp? collider. We measure the fractions of longitudinal and right-handed W bosons to be f?=0.6690.102[0.078(stat.)0.065(syst.)] and f?=0.0230.053[0.041(stat.)0.034(syst.)], respectively. This result is consistent at the 98% level with the standard model. A measurement with f? fixed to the value from the standard model yields f?=0.0100.037[0.022(stat.)0.030(syst.)].

  12. Measurement of the t-Channel Single Top Quark Production Cross Section in pp Collisions at [sqrt]s=7??TeV

    E-Print Network [OSTI]

    Alver, Burak Han

    Electroweak production of the top quark is measured for the first time in pp collisions at ?s=7??TeV, using a data set collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36??pb-1. ...

  13. Measurement of associated production of vector bosons and top quark-antiquark pairs in pp collisions at sqrt[s]=7??TeV

    E-Print Network [OSTI]

    Apyan, Aram

    The first measurement of vector-boson production associated with a top quark-antiquark pair in proton-proton collisions at ?s=7??TeV is presented. The results are based on a data set corresponding to an integrated luminosity ...

  14. Search for Flavor-Changing Neutral Currents in Top-Quark Decays t ? Zq in pp Collisions at ?s = 8 TeV

    E-Print Network [OSTI]

    Apyan, Aram

    A search for flavor-changing neutral currents in top-quark decays t ? Zq is performed in events produced from the decay chain t[bar over t] ? Zq + Wb, where both vector bosons decay leptonically, producing a final state ...

  15. Higgs boson mass bounds in the presence of a heavy fourth quark family

    E-Print Network [OSTI]

    John Bulava; Philipp Gerhold; Karl Jansen; Jim Kallarackal; Attila Nagy

    2013-01-16T23:59:59.000Z

    We present Higgs boson mass bounds in a lattice regularization allowing thus for non-perturbative investigations. In particular, we employ a lattice modified chiral invariant Higgs-Yukawa model using the overlap operator. We show results for the upper and lower Higgs boson mass bounds in the presence of a heavy mass-degenerate quark doublet with masses ranging up to 700 GeV. We perform infinite volume extrapolations in most cases, and examine several values of the lattice cutoff. Furthermore, we argue that the lower Higgs boson mass bound is stable with respect to the addition of higher dimensional operators to the scalar field potential. Our results have severe consequences for the phenomenology of a fourth generation of quarks if a light Higgs boson is discovered at the LHC.

  16. First results from $2+1$ dynamical quark flavors on an anisotropic lattice: light-hadron spectroscopy and setting the strange-quark mass

    SciTech Connect (OSTI)

    Lin, Huey-Wen; Cohen, Saul; Dudek, Jozef; Edwards, Robert; Joo, Balint; Richards, David; Bulava, John; Foley, Justin; Morningstar, Colin; Engelson, Eric; Wallace, Stephen; Juge, Jimmy; Mathur, Nilmani; Peardon, Michael; Ryan, Sinead

    2009-02-01T23:59:59.000Z

    We present the first light-hadron spectroscopy on a set of $N_f=2+1$ dynamical, anisotropic lattices. A convenient set of coordinates that parameterize the two-dimensional plane of light and strange-quark masses is introduced. These coordinates are used to extrapolate data obtained at the simulated values of the quark masses to the physical light and strange-quark point. A measurement of the Sommer scale on these ensembles is made and the performance of the hybrid Monte Carlo algorithm used for generating the ensembles is estimated.

  17. First results from 2+1 dynamical quark flavors on an anisotropic lattice: Light-hadron spectroscopy and setting the strange-quark mass

    SciTech Connect (OSTI)

    Lin, H.-W.; Cohen, Saul D.; Dudek, Jozef; Edwards, Robert G.; Joo, Balint; Richards, David G. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Bulava, John; Foley, Justin; Morningstar, Colin [Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Engelson, Eric; Wallace, Stephen [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Juge, K. Jimmy [Department of Physics, University of the Pacific, Stockton, California 95211 (United States); Mathur, Nilmani [Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Peardon, Michael J.; Ryan, Sinead M. [School of Mathematics, Trinity College, Dublin 2 (Ireland)

    2009-02-01T23:59:59.000Z

    We present the first light-hadron spectroscopy on a set of N{sub f}=2+1 dynamical, anisotropic lattices. A convenient set of coordinates that parameterize the two-dimensional plane of light and strange-quark masses is introduced. These coordinates are used to extrapolate data obtained at the simulated values of the quark masses to the physical light and strange-quark point. A measurement of the Sommer scale on these ensembles is made, and the performance of the hybrid Monte Carlo algorithm used for generating the ensembles is estimated.

  18. Measurement of the Mass Difference between t and t[over-bar] Quarks

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present a direct measurement of the mass difference between t and t[over-bar] quarks using tt[over-bar] candidate events in the lepton+jets channel, collected with the CDF II detector at Fermilabs 1.96 TeV Tevatron ...

  19. Contribution of quark-mass-dependent operators to higher twist effects in deep-inelastic scattering

    SciTech Connect (OSTI)

    Lee, S.H. [Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)] [Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)

    1994-03-01T23:59:59.000Z

    We look at the contribution of quark-mass-dependent twist-4 operators to the second moments of spin-averaged structure functions and the Bjorken sum rule. Its contribution is non-negligible in the former case due to large Wilson coefficients. We also discuss the values of the twist-4 spin-2 nucleon matrix element within present experimental constraints.

  20. Mass generation via the Higgs boson and the quark condensate of the QCD vacuum

    E-Print Network [OSTI]

    Schumacher, Martin

    2015-01-01T23:59:59.000Z

    The Higgs boson, recently discovered with a mass of 125.7 GeV is known to mediate the masses of elementary particles, but only 2% of the mass of the nucleon. Extending a previous investigation [1] and including the strange-quark sector, hadron masses are derived from the quark condensate of the QCD vacuum and from the effects of the Higgs boson. These calculations include the $\\pi$ meson, the nucleon and the scalar mesons $\\sigma(600)$, $\\kappa(800)$, $a_0(980)$ $f_0(980)$ and $f_0(1370)$. The predicted second $\\sigma$ meson $\\sigma'(1344)=|s\\bar{s}\\rangle$, is investigated and identified with the $f_0(1370)$ meson. An outlook is given on the hyperons $\\Lambda$, $\\Sigma^{0,\\pm}$ and $\\Xi^{0,-}$.

  1. Spin analyzing power for polarized top decays with jets

    E-Print Network [OSTI]

    Yoshio Kitadono; Hsiang-nan Li

    2014-04-10T23:59:59.000Z

    We perform perturbative QCD factorization of infrared radiations associated with an energetic $b$ quark from a polarized top quark decay, taking the semi-leptonic channel as an example. The resultant formula is expressed as a convolution of an infrared-finite heavy-quark kernel with a $b$-quark jet function. Evaluating the heavy-quark kernel up to leading order in the coupling constant and adopting the jet function from QCD resummation, we predict the dependence of the spin analyzing power for a polarized top quark on the invariant mass of the $b$-quark jet. It is observed that the spin analyzing power could be enhanced by a factor 2 compared to the inclusive case with the jet mass being integrated over. It is worthwhile to test experimentally the enhancement of the spin analyzing power due to the inclusion of jet dynamics.

  2. Top-antitop and Top-top Resonances in the Dilepton Channel at the CERN LHC

    E-Print Network [OSTI]

    Yang Bai; Zhenyu Han

    2009-04-12T23:59:59.000Z

    We perform a model-independent study for top-antitop and top-top resonances in the dilepton channel at the Large Hadtron Collider. In this channel, we can solve the kinematic system to obtain the momenta of all particles including the two neutrinos, and hence the resonance mass and spin. For discovering top-antitop resonances, the dilepton channel is competitive to the semileptonic channel because of the good resolution of lepton momentum measurement and small standard model backgrounds. Moreover, the charges of the two leptons can be identified, which makes the dilepton channel advantageous for discovering top-top resonances and for distinguishing resonance spins. We discuss and provide resolutions for difficulties associated with heavy resonances and highly boosted top quarks.

  3. Search for the associated production of the Higgs boson with a top quark pair in multi-lepton final states with the ATLAS detector

    E-Print Network [OSTI]

    The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    A search for the associated production of the Higgs boson with a top quark pair is performed in multi-lepton final states using 20.3 fb$^{-1}$ of proton-proton collision data recorded by the ATLAS experiment at $\\sqrt{s}=8$ TeV at the Large Hadron Collider. Five final states, targeting the decays $H\\to WW^*$, $\\tau\\tau$, and $ZZ^*$, are examined for the presence of the Standard Model (SM) Higgs boson: two same-charged light leptons ($e$ or $\\mu$) without an additional hadronically decaying tau; three light leptons; two same-charged light leptons with an additional hadronically decaying tau; four light leptons; and one light lepton and two hadronically decaying taus. No significant excess of events is observed above the background expectation. The best fit for the $t\\bar t H$ production cross section, assuming a Higgs boson mass of 125 GeV, is $2.1 ^{+1.4}_{-1.2}$ times the SM expectation, and the observed (expected) upper limit at the 95% confidence level is 4.7 (2.4) times the SM rate. The $p$-value for comp...

  4. Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector

    E-Print Network [OSTI]

    ATLAS Collaboration

    2015-01-01T23:59:59.000Z

    A search for the associated production of the Higgs boson with a top quark pair is performed in multilepton final states using 20.3 fb$^{-1}$ of proton-proton collision data recorded by the ATLAS experiment at $\\sqrt{s}=8$ TeV at the Large Hadron Collider. Five final states, targeting the decays $H\\to WW^*$, $\\tau\\tau$, and $ZZ^*$, are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons ($e$ or $\\mu$) without a hadronically decaying $\\tau$ lepton; three light leptons; two same-charge light leptons with a hadronically decaying $\\tau$ lepton; four light leptons; and one light lepton and two hadronically decaying $\\tau$ leptons. No significant excess of events is observed above the background expectation. The best fit for the $t\\bar t H$ production cross section, assuming a Higgs boson mass of 125 GeV, is $2.1 ^{+1.4}_{-1.2}$ times the SM expectation, and the observed (expected) upper limit at the 95% confidence level is 4.7 (2.4) times the SM rate. The $p$-value f...

  5. Heavy-Quark Free Energy, Debye Mass, and Spatial String Tension at Finite Temperature in Two Flavor Lattice QCD with Wilson Quark Action

    E-Print Network [OSTI]

    WHOT-QCD Collaboration; :; Y. Maezawa; N. Ukita; S. Aoki; S. Ejiri; T. Hatsuda; N. Ishii; K. Kanaya

    2007-02-13T23:59:59.000Z

    We study Polyakov loop correlations and spatial Wilson loop at finite Temperature in two-flavor QCD simulations with the RG-improved gluon action and the clover-improved Wilson quark action on a $ 16^3 \\times 4$ lattice. From the line of constant physics at $m_{\\rm PS}/m_{\\rm V}=0.65$ and 0.80, we extract the heavy-quark free energies, the effective running coupling $g_{\\rm eff}(T)$ and the Debye screening mass $m_D(T)$ for various color channels of heavy quark--quark and quark--anti-quark pairs above the critical temperature. The free energies are well approximated by the screened Coulomb form with the appropriate Casimir factors at high temperature. The magnitude and the temperature dependence of the Debye mass are compared to those of the next-to-leading order thermal perturbation theory and to a phenomenological formula in terms of $g_{\\rm eff}(T)$. We make a comparison between our results with the Wilson quark action and the previous results with the staggered quark action. The spatial string tension is also studied in the high temperature phase and is compared to the next-to-next-leading order prediction in an effective theory with dimensional reduction.

  6. Top polarization as a probe of new physics

    E-Print Network [OSTI]

    Rohini M Godbole; Saurabh D Rindani; Kumar Rao; Ritesh K Singh

    2010-04-16T23:59:59.000Z

    We investigate the effects of new physics scenarios containing a high mass vector resonance on top pair production at the LHC, using the polarization of the produced top. In particular we use kinematic distributions of the secondary lepton coming from top decay, which depends on top polarization, as it has been shown that the angular distribution of the decay lepton is insensitive to the anomalous tbW vertex and hence is a pure probe of new physics in top quark production. Spin sensitive variables involving the decay lepton are used to probe top polarization. Some sensitivity is found for the new couplings of the top.

  7. Enhancing the Sensitivity to New Physics in the top-antitop Invariant Mass Distribution

    SciTech Connect (OSTI)

    Alvarez, Ezequiel; /Univ. Nacional San Luis /SLAC

    2012-06-14T23:59:59.000Z

    We propose selection cuts on the LHC t{bar t} production sample which should enhance the sensitivity to New Physics signals in the study of the t{bar t} invariant mass distribution. We show that selecting events in which the t{bar t} object has little transverse and large longitudinal momentum enlarges the quark-fusion fraction of the sample and therefore increases its sensitivity to New Physics which couples to quarks and not to gluons. We find that systematic error bars play a fundamental role and assume a simple model for them. We check how a non-visible new particle would become visible after the selection cuts enhance its resonance bump. A final realistic analysis should be done by the experimental groups with a correct evaluation of the systematic error bars.

  8. Top physics at LHC with ttbar events

    E-Print Network [OSTI]

    F. Hubaut

    2006-05-10T23:59:59.000Z

    The new CERN proton-proton collider, the LHC, is about to start in 2007 its data taking. Millions of top quarks will be available out of these data, allowing to perform a wide range of precision measurements and searches for new physics. An overview of the planned top physics program accessible with ttbar events is given for the ATLAS and CMS experiments. A particular emphasis is put on the precision measurements of the top mass, top polarization and searches for new physics in top production and decay.

  9. QCD thermodynamics with $N_f=2+1$ near the continuum limit at realistic quark masses

    E-Print Network [OSTI]

    Takashi Umeda

    2006-10-03T23:59:59.000Z

    We report on our study of QCD thermodynamics with 2+1 flavors of dynamical quarks. In this proceeding we present several thermodynamic quantities and our recent calculation of the critical temperature. In order to investigate the thermodynamic properties of QCD near the continuum limit we adopt improved staggered (p4) quarks coupled with tree-level Symanzik improved glue on $N_t=4$ and 6 lattices. The simulations are performed with a physical value of the strange quark mass and light quark masses which are in the range of $m_q/m_s=0.05-0.4$. The lightest quark mass corresponds to a pion mass of about 150 MeV.

  10. Top Physics at LHC

    E-Print Network [OSTI]

    M. Vander Donckt; for the CMS; ATLAS Collaborations

    2008-05-21T23:59:59.000Z

    The Large Hadron Collider (LHC) will provide a huge amount of top-antitop events, making the LHC a top quark factory, producing 1 tt pair per second at a luminosity of 10^33cm-2s-1. A large top quark sample will be available from the start of LHC and will play an important role in commissioning the CMS and ATLAS detectors. An overview of the top quark measurements during the first data-taking period is given.

  11. Search for electroweak single top quark production with cdf in proton - anti-proton collisions at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Walter, Thorsten

    2005-06-01T23:59:59.000Z

    In this thesis two searches for electroweak single top quark production with the CDF experiment have been presented, a cutbased search and an iterated discriminant analysis. Both searches find no significant evidence for electroweak single top production using a data set corresponding to an integrated luminosity of 162 pb{sup -1} collected with CDF. Therefore limits on s- and t-channel single top production are determined using a likelihood technique. For the cutbased search a likelihood function based on lepton charge times pseudorapidity of the non-bottom jet was used if exactly one bottom jet was identified in the event. In case of two identified bottom jets a likelihood function based on the total number of observed events was used. The systematic uncertainties have been treated in a Bayesian approach, all sources of systematic uncertainties have been integrated out. An improved signal modeling using the MadEvent Monte Carlo program matched to NLO calculations has been used. The obtained limits for the s- and t-channel single top production cross sections are 13.6 pb and 10.1 pb, respectively. To date, these are most stringent limits published for the s- and the t-channel single top quark production modes.

  12. Spectral properties of quarks above Tc -- thermal mass, dispersion relation, and self-energy --

    E-Print Network [OSTI]

    Masakiyo Kitazawa

    2010-11-12T23:59:59.000Z

    Spectral properties of quarks above the critical temperature for deconfinement are analyzed in quenched lattice QCD on lattices of size 128^3x16. We study quark spectral function in energy and momentum space, focusing on the values of the thermal mass and the dispersion relations of normal and plasmino modes at nonzero momentum, as well as their spatial volume dependence. Our numerical result suggests that the dispersion relation of the plasmino mode has a minimum at nonzero momentum even near the critical temperature. The quark self-energy is also analyzed by using the analyticy of the inverse propagator, which is found to be consistent with the spectral function estimated by the two-pole ansatz.

  13. High-luminosity primary vertex selection in top-quark studies using the Collider Detector at Fermilab

    SciTech Connect (OSTI)

    Buzatu, Adrian; /McGill U.

    2006-08-01T23:59:59.000Z

    Improving our ability to identify the top quark pair (t{bar t}) primary vertex (PV) on an event-by-event basis is essential for many analyses in the lepton-plus-jets channel performed by the Collider Detector at Fermilab (CDF) Collaboration. We compare the algorithm currently used by CDF (A1) with another algorithm (A2) using Monte Carlo simulation at high instantaneous luminosities. We confirm that A1 is more efficient than A2 at selecting the t{bar t} PV at all PV multiplicities, both with efficiencies larger than 99%. Event selection rejects events with a distance larger than 5 cm along the proton beam between the t{bar t} PV and the charged lepton. We find flat distributions for the signal over background significance of this cut for all cut values larger than 1 cm, for all PV multiplicities and for both algorithms. We conclude that any cut value larger than 1 cm is acceptable for both algorithms under the Tevatron's expected instantaneous luminosity improvements.

  14. Measurement of the t-Channel Single Top Quark Production Cross Section in pp Collisions at sqrt[s]=7??TeV

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; et al.

    2011-08-01T23:59:59.000Z

    Electroweak production of the top quark is measured in pp collisions at sqrt(s) = 7 TeV, using a dataset collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 inverse picobarns. With an event selection optimized for t-channel production, two complementary analyses are performed. The first one exploits the special angular properties of the signal, together with background estimates from data. The second approach uses a multivariate analysis technique to probe the compatibility with signal topology expected from electroweak top quark production. The combined measurement of the cross section is 83.6 +/- 29.8 (stat.+syst.) +/- 3.3 (lumi.) pb, consistent with the standard model expectation.

  15. Observation of top-quark production in the forward region with LHCb together with $(b,c)$-jet tagging and $W + (b, c)$ jets production measurements @7 and 8 TeV

    E-Print Network [OSTI]

    Coco, Victor

    2015-01-01T23:59:59.000Z

    Observation of top-quark production in the forward region with LHCb together with $(b,c)$-jet tagging and $W + (b, c)$ jets production measurements @7 and 8 TeV

  16. Search for s-Channel Single-Top-Quark Production in Events with Missing Energy Plus Jets in p[bar over p] Collisions at ?s = 1.96 TeV

    E-Print Network [OSTI]

    Gomez-Ceballos, Guillelmo

    The first search for single-top-quark production from the exchange of an s-channel virtual W boson using events with an imbalance in the total transverse energy, b-tagged jets, and no identified leptons is presented. ...

  17. Higgs boson mass bounds in the presence of a very heavy fourth quark generation

    E-Print Network [OSTI]

    P. Gerhold; K. Jansen; J. Kallarackal

    2010-11-07T23:59:59.000Z

    We study the effect of a potential fourth quark generation on the upper and lower Higgs boson mass bounds. This investigation is based on the numerical evaluation of a chirally invariant lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model. In particular, the considered model obeys a Ginsparg-Wilson version of the underlying ${SU}(2)_L\\times {U}(1)_Y$ symmetry, being a global symmetry here due to the neglection of gauge fields in this model. We present our results on the modification of the upper and lower Higgs boson mass bounds induced by the presence of a hypothetical very heavy fourth quark doublet. Finally, we compare these findings to the standard scenario of three fermion generations.

  18. Top-Down Mass Spectrometry Imaging of Intact Proteins by LAESI FT-ICR MS

    E-Print Network [OSTI]

    Kiss, Andrs; Reschke, Brent R; Powell, Matthew J; Heeren, Ron M A

    2013-01-01T23:59:59.000Z

    Laser Ablation Electrospray Ionization is a recent development in mass spectrometry imaging. It has been shown that lipids and small metabolites can be imaged in various samples such as plant material, tissue sections or bacterial colonies without anysample pre-treatment. Further, laser ablation electrospray ionization has been shown to produce multiply charged protein ions from liquids or solid surfaces. This presents a means to address one of the biggest challenges in mass spectrometry imaging; the identification of proteins directly from biological tissue surfaces. Such identification is hindered by the lack of multiply charged proteins in common MALDI ion sources and the difficulty of performing tandem MS on such large, singly charged ions. We present here top-down identification of intact proteins from tissue with a LAESI ion source combined with a hybrid ion-trap FT-ICR mass spectrometer. The performance of the system was first tested with a standard protein with ECD and IRMPD fragmentation to prove the...

  19. Up- and down-quark masses from finite-energy QCD sum rules to five loops

    SciTech Connect (OSTI)

    Dominguez, C. A.; Nasrallah, N. F.; Roentsch, R. H.; Schilcher, K. [Centre for Theoretical Physics and Astrophysics, University of Cape Town, Rondebosch 7700 (South Africa) and Department of Physics, Stellenbosch University, Stellenbosch 7600 (South Africa); Faculty of Science, Lebanese University, Tripoli (Lebanon); Centre for Theoretical Physics and Astrophysics, University of Cape Town, Rondebosch 7700 (South Africa); Institut fuer Physik, Johannes Gutenberg-Universitaet, Staudingerweg 7, D-55099 Mainz (Germany)

    2009-01-01T23:59:59.000Z

    The up- and down-quark masses are determined from an optimized QCD finite-energy sum rule involving the correlator of axial-vector divergences, to five-loop order in perturbative QCD, and including leading nonperturbative QCD and higher order quark-mass corrections. This finite-energy sum rule is designed to reduce considerably the systematic uncertainties arising from the (unmeasured) hadronic resonance sector, which in this framework contributes less than 3-4% to the quark mass. This is achieved by introducing an integration kernel in the form of a second degree polynomial, restricted to vanish at the peak of the two lowest lying resonances. The driving hadronic contribution is then the pion pole, with parameters well known from experiment. The determination is done in the framework of contour improved perturbation theory, which exhibits a very good convergence, leading to a remarkably stable result in the unusually wide window s{sub 0}=1.0-4.0 GeV{sup 2}, where s{sub 0} is the radius of the integration contour in the complex energy (squared) plane. The results are m{sub u}(Q=2 GeV)=2.9{+-}0.2 MeV, m{sub d}(Q=2 GeV)=5.3{+-}0.4 MeV, and (m{sub u}+m{sub d})/2=4.1{+-}0.2 MeV (at a scale Q=2 GeV)

  20. Top Physics at the LHC

    E-Print Network [OSTI]

    P. de Jong

    2009-02-27T23:59:59.000Z

    The LHC will be a top quark factory. In this note, the central role of the top quark for LHC physics will be discussed, and an overview will be given of the studies of top quark properties in preparation, with an emphasis on the systematic uncertainties that will dominate most measurements.

  1. Searching the inclusive l gamma EslashT+b-quark signature for radiative top quark decay and non-standard-model processes

    E-Print Network [OSTI]

    Xie, Si

    We compare the inclusive production of events containing a lepton (?), a photon (?), significant transverse momentum imbalance (E?[subscript T]), and a jet identified as containing a b-quark, to SM predictions. The search ...

  2. Equilibrium configurations for quark-diquark stars and the problem of Her X-1 mass

    E-Print Network [OSTI]

    J. E. Horvath; J. A. de Freitas Pacheco

    1996-11-20T23:59:59.000Z

    We report new calculations of the physical properties of a quark-diquark plasma. A vacuum contribution is taken into account and is responsible for the appearance of a stable state at zero pressure and at a baryon density of about 2.2 times the nuclear matter density in this model. The resulting equation of state was used to integrate numerically the Tolman-Oppenheimer-Volkoff equations. The mass-radius relationship has been derived from a series of equilibrium configurations constituted by a mixture of quarks and diquarks. These stellar models, which are representative of a whole class, may be helpful to understand the possible compactness of the X-ray source Her X-1 and related objects.

  3. Gluon condensates and c, b quark masses from quarkonia ratios of moments

    E-Print Network [OSTI]

    Stephan Narison

    2011-10-13T23:59:59.000Z

    We extract (for the first time) the ratio of the gluon condensate / expressed in terms of the liquid instanton radius rho_c from charmonium moments sum rules by examining the effects of in the determinations of both rho_c and the running MS mass m_c(m_c). Using a global analysis of selected ratios of moments at different Q^2=0, 4m_c^2 and 8m_c^2 and taking from 0.06 GeV^4, where the estimate of rho_c is almost independent of , we deduce: rho_c=0.98(21) GeV^{-1} which corresponds to = (31+- 13) GeV^2 . The value of m_c(m_c) is less affected (within the errors) by the variation of , where a common solution from different moments are reached for greater than 0.02 GeV^4. Using the values of =0.06(2) GeV^4 from some other channels and the previous value of , we deduce: m_c(m_c)=1260(18) MeV and m_b(m_b)=4173(10) MeV, where an estimate of the 4-loops contribution has been included. Our analysis indicates that the errors in the determinations of the charm quark mass without taking into account the ones of the gluon condensates have been underestimated. To that accuracy, one can deduce the running light and heavy quark masses and their ratios evaluated at M_Z, where it is remarkable to notice the approximate equalities: m_s/m_u= m_b/m_s= m_t/m_b= 51(4), which might reveal some eventual underlying novel symmetry of the quark mass matrix in some Grand Unified Theories.

  4. Search for the pair production of scalar top quarks in the acoplanar charm jet final state in p anti-p collisions at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Aguilo, E.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; /Buenos Aires U. /Rio de

    2006-11-01T23:59:59.000Z

    A search for the pair production of scalar top quarks, {bar t}, has been performed in 360 pb{sup -1} of data from p{bar p} collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron collider. The {bar t} decay mode considered is {bar t} {yields} c{bar {chi}}{sub 1}{sup 0}, where {bar {chi}}{sub 1}{sup 0} is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data show good agreement with the standard model expectation, and a 95% C.L. exclusion domain in the (m{sub {tilde t}}, m{sub {tilde {chi}}{sub 1}{sup 0}}) plane has been determined, extending the domain excluded by previous experiments.

  5. Evidence for Associated Production of a Single Top Quark and W Boson in pp Collisions at ?s=7??TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Aguilo, E.; Bergauer, T.; Dragicevic, M.; Er, J.; Fabjan, C.; Friedl, M.; Frhwirth, R.; Ghete, V. M.; Hammer, J.; Hrmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knnz, V.; Krammer, M.; Krtschmer, I.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schfbeck, R.; Strauss, J.; Taurok, A.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, M.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Staykova, Z.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; DHondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hreus, T.; Lonard, A.; Marage, P. E.; Mohammadi, A.; Reis, T.; Thomas, L.; Vander Marcken, G.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Verwilligen, P.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Castello, R.; Ceard, L.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins Junior, M.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Ald Jnior, W. L.; Carvalho, W.; Custdio, A.; Da Costa, E. M.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Soares Jorge, L.; Sznajder, A.; Anjos, T. S.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, Y.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Teng, H.; Wang, D.; Zhang, L.; Zou, W.; Avila, C.; Gomez, J. P.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Mntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Hrknen, J.; Heikkinen, A.; Karimki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampn, T.; Lassila-Perini, K.; Lehti, S.; Lindn, T.; Luukka, P.; Menp, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Karjalainen, A.; Korpela, A.; Tuuva, T.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Millischer, L.; Nayak, A.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dalchenko, M.; Dobrzynski, L.; Granier de Cassagnac, R.; Haguenauer, M.; Min, P.; Mironov, C.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Ferro, C.; Fontaine, J.-C.; Gel, D.; Goerlach, U.; Juillot, P.; Le Bihan, A.-C.; Van Hove, P.; Fassi, F.; Mercier, D.; Beauceron, S.; Beaupere, N.; Bondu, O.; Boudoul, G.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sgandurra, L.; Sordini, V.; Tschudi, Y.; Verdier, P.; Viret, S.; Roinishvili, V.; Anagnostou, G.; Autermann, C.; Beranek, S.; Edelhoff, M.; Feld, L.; Heracleous, N.

    2013-01-01T23:59:59.000Z

    Evidence is presented for the associated production of a single top quark and W boson in pp collisions at ?s =7??TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 4.9??fb?1. The measurement is performed using events with two leptons and a jet originated from a b quark. A multivariate analysis based on kinematic properties is utilized to separate the tt background from the signal. The observed signal has a significance of 4.0? and corresponds to a cross section of 16+5?4?pb, in agreement with the standard model expectation of 15.60.4+1.0?1.2?pb .

  6. Direct measurement of the top quark mass by the DO" Collaboration B. Abbott,30

    E-Print Network [OSTI]

    . Genser,14 C. E. Gerber,14 B. Gibbard,4 S. Glenn,7 B. Gobbi,33 A. Goldschmidt,23 B. Go´mez,1 G. Go´mez,25

  7. Measurement of the top quark mass in the dilepton channel B. Abbott,40

    E-Print Network [OSTI]

    . Gerber,23 Y. Gershtein,13 B. Gibbard,43 B. Gobbi,26 B. Go´mez,4 G. Go´mez,33 P. I. Goncharov,15 J. L

  8. Combination of the top-quark mass measurements from the Tevatron collider T. Aaltonen,12

    E-Print Network [OSTI]

    Fermilab

    . Brigliadoria ,33 R. Brock,98 C. Bromberg,98 A. Bross,76 D. Brown,17 J. Brown,17 E. Brucken,12 X.B. Bu,76 J. Camarda,54 M. Campanelli,64 M. Campbell,96 F. Canelli,77 B. Carls,81 D. Carlsmith,125 R. Carosi,36 S.M. Abazov,48 B. Abbott,112 B.S. Acharya,31 M. Adams,78 T. Adams,74 G.D. Alexeev,48 G. Alkhazov,52 A. Altona

  9. Top Quark Mass Measurement in the 2 fb -1 Tight Lepton and Isolated Track Sample using

    E-Print Network [OSTI]

    Quigg, Chris

    have been specified (see below). y Part of this work was supported by DARA grant WE2 50 OR 9411. 1 #12

  10. Search for the single top quarks produced in s-channel via electroweak interactions at s = 1-96 at the Tevatron

    SciTech Connect (OSTI)

    Jabeen, Shabnam; /Kansas U.

    2006-01-01T23:59:59.000Z

    The authors present a search for single top quarks produced in the s-channel electroweak production mode. The search is performed in the electron+jets decay channels, with one or more secondary-vertex tagged jets to indicate the presence of a b-jet and hence improving the signal:background ratio. Separation between signal and background is further enhanced by the use of Feed Forward Neural networks. 360 pb{sup -1} of Run II data used for this analysis was delivered by the Tevatron, and collected by D0 between August 2002 and August 2004. The resulting 95% confidence level upper limit is 4 pb.

  11. CP violating anomalous top-quark coupling in p$\\bar{p}$ collision at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Lee, Sehwook; /Iowa State U.

    2011-04-01T23:59:59.000Z

    We conduct the first study of the T-odd correlations in tt events produced in p{bar p} collision at the Fermilab Tevatron collider that can be used to search for CP violation. We select events which have lepton+jets final states to identify t{bar t} events and measure counting asymmetries of several physics observables. Based on the result, we search the top quark anomalous couplings at the production vertex at the Tevatron. In addition, Geant4 development, photon identification, the discrimination of a single photon and a photon doublet from {pi}{sup 0} decay are discussed in this thesis.

  12. Search for pair production of scalar top quarks decaying to a tau lepton and a b quark in 1.96-tev ppbar collisions

    E-Print Network [OSTI]

    Khotilovich, Vadim Gennadyevich

    2009-05-15T23:59:59.000Z

    ~t1 decays into a tau lepton and a b quark, with branching ratio B, and search for final states containing either an electron or a muon from a leptonic tau decay, a hadronically decaying tau lepton, and two or more jets. Two candidate events pass my...

  13. T-Quark Mass and Hyperfinite II1 von Neumann factor

    E-Print Network [OSTI]

    Frank Smith Jr.

    2004-02-12T23:59:59.000Z

    A theoretical model based on the D4 Lie Algebra and Hermitian Symmetric Spaces D5 / D4xU(1) and E6 / D5xU(1) allows calculation of ratios of tree-level particle masses (quark masses being constituent masses): Me-neutrino = Mmu-neutrino = Mtau-neutrino = 0 Me = 0.5110 MeV (assumed); Md = Mu = 312.8 MeV; Mmu = 104.8 MeV; Ms = 625 MeV; Mc = 2.09 GeV; Mtau = 1.88 GeV; Mb = 5.63 GeV; Mt = 130 GeV; W+/- mass = 80.326 GeV; Z0 mass = 91.862 GeV; Higgs mass = 145.8 GeV; Higgs VEV = 252.5 GeV; and ratios of force strength constants: (Ggravity)(Mproton)2 = 5 x 10-39 (asssumed); EM fine structure constant = 1/137.03608; Gfermi = (Gweak)(Mproton)2 = 1.02 x 10-5; color force strength = 0.6286 (at 0.245 GeV). With Nonperturbative QCD etc taken into account the color force strength = 0.123 (at 91 GeV). Fermilab (1994) says that Mt = about 170 GeV but I say (1984) that Mt = about 130 GeV. The theoretical Lagrangian is based on the structure of the real Cl(1,7) Clifford algebra which, through 8-fold periodicity, may produce a real Hyperfinite II1 von Neumann Algebra factor.

  14. Implications of the anomalous top quark couplings in B{sub s}-B{sub s} mixing, B{yields}X{sub s}{gamma} and top quark decays

    SciTech Connect (OSTI)

    Lee, Jong Phil; Lee, Kang Young [School of Physics, Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of); Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of)

    2008-09-01T23:59:59.000Z

    Combined analysis of recent measured B{sub s}-B{sub s} mixing and B{yields}X{sub s}{gamma} decays provides constraints on the anomalous tsW couplings. We discuss the perspectives to examine the anomalous tsW couplings through Cabibbo-Kobayashi-Maskawa quark-mixing matrix-suppressed t{yields}sW decays at the LHC.

  15. Quantitative Analysis of Human Salivary Gland-Derived Intact Proteome Using Top-Down Mass Spectrometry

    SciTech Connect (OSTI)

    Wu, Si; Brown, Joseph N.; Tolic, Nikola; Meng, Da; Liu, Xiaowen; Zhang, Haizhen; Zhao, Rui; Moore, Ronald J.; Pevzner, Pavel A.; Smith, Richard D.; Pasa-Tolic, Ljiljana

    2014-05-31T23:59:59.000Z

    There are several notable challenges inherent to fully characterizing the entirety of the human saliva proteome using bottom-up approaches, including polymorphic isoforms, post-translational modifications, unique splice variants, deletions, and truncations. To address these challenges, we have developed a top-down based liquid chromatography-mass spectrometry (LC-MS) approach, which cataloged 20 major human salivary proteins with a total of 83 proteoforms, containing a broad range of post-translational modifications. Among these proteins, several previously reported disease biomarker proteins were identified at the intact protein level, such as beta-2 microglobulin (B2M). In addition, intact glycosylated proteoforms of several saliva proteins were also characterized, including intact N-glycosylated protein prolactin inducible protein (PIP) and O-glycosylated acidic protein rich protein (aPRP). These characterized proteoforms constitute an intact saliva proteoform database, which was used for quantitative comparison of intact salivary proteoforms among six healthy individuals. Human parotid (PS) and submandibular/sublingual gland (SMSL) secretion samples (2 ?g of protein each) from six healthy individuals were compared using RPLC coupled with the 12T FTICR mass spectrometer. Significantly different protein and PTM patterns were resolved with high reproducibility between PS and SMSL glands. The results from this study provide further insight into the potential mechanisms of PTM pathways in oral glandular secretion, expanding our knowledge of this complex yet easily accessible fluid. Intact protein LC-MS approach presented herein can potentially be applied for rapid and accurate identification of biomarkers from only a few microliters of human glandular saliva.

  16. Differential top pair cross section and top anti-top plus jets Physics

    E-Print Network [OSTI]

    Malgorzata Worek

    2013-02-14T23:59:59.000Z

    A brief summary of the current status of the next-to-leading order QCD corrections to top quark pair production and the associated production of top anti-top with jet(s) in different configurations, i.e. with one jet, two jets and another top anti-top pair, is presented.

  17. Higgs boson discovery through top-partners decays using jet substructure

    SciTech Connect (OSTI)

    Kribs, Graham D. [Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States); Department of Physics, University of Oregon, Eugene, Oregon 97403 (United States); Martin, Adam [Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States); Roy, Tuhin S. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)

    2011-11-01T23:59:59.000Z

    Top partners--vectorlike quarks which mix predominantly with the top quark, are simple extensions of the standard model present in many theories of new physics such as little Higgs models, topcolor models, and extra dimensions. Through renormalizable mixing with the top quark, these top partners inherit couplings to the Higgs boson. Higgs bosons produced from the decay of top partners are often highly boosted and ideal candidates for analyses based on jet substructure. Using substructure methods, we show that light Higgs bosons decaying to bb can be discovered at the 14 TeV LHC with less than 10 fb{sup -1} for top-partner masses up to 1 TeV.

  18. Measurement of the W boson helicity in top quark decays using 5.4 fb$^{\\boldsymbol{-1}}$ of $\\boldsymbol{p\\bar{p}}$ collision data

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls; Alverson, George O.; /Northeastern U.; Alves, Gilvan Augusto; /Rio de Janeiro, CBPF; Ancu, Lucian Stefan; /Nijmegen U. /Fermilab

    2010-11-01T23:59:59.000Z

    We present a measurement of the helicity of the W boson produced in top quark decays using t{bar t} decays in the {ell}+jets and dilepton final states selected from a sample of 5.4 fb{sup -1} of collisions recorded using the D0 detector at the Fermilab Tevatron p{bar p} collider. We measure the fractions of longitudinal and right-handed W bosons to be f{sub 0} = 0.669 {+-} 0.102 [{+-}0.078 (stat.) {+-} 0.065 (syst.)] and f{sub +} = 0.023 {+-} 0.053 [{+-}0.041 (stat.){+-}0.034 (syst.)], respectively. This result is consistent at the 98% level with the standard model. A measurement with f{sub 0} fixed to the value from the standard model yields f{sub +} = 0.010 {+-} 0.037 [{+-}0.022 (stat.) {+-} 0.030 (syst.)].

  19. Measurements of single top quark production cross sections and |Vtb| in pp? collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Alverson, George O; Alves, Gilvan Augusto; et al

    2011-12-05T23:59:59.000Z

    We present measurements of production cross sections of single top quarks in pp? collisions at ?s = 1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of ?(pp? ? tb + X, tqb + X) = 3.43-0.74+0.73 pb and use it to extract the CKM matrix element 0.79 more|Vtb| {le} 1 at the 95% C.L. We also measure ?(pp? ? tb + X) = 0.68-0.35+0.38pb and ?(pp? ? tqb + X) = 2.86-0.63+0.69pb when assuming, respectively, tqb and tb production rates as predicted by the standard model.less

  20. Measurements of single top quark production cross sections and |Vtb| in pp? collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U., Augustana College, Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Aoki, Masato [Fermilab; Louisiana Tech U.

    2011-12-05T23:59:59.000Z

    We present measurements of production cross sections of single top quarks in pp? collisions at ?s = 1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of ?(pp? ? tb + X, tqb + X) = 3.43-0.74+0.73 pb and use it to extract the CKM matrix element 0.79 tb| {le} 1 at the 95% C.L. We also measure ?(pp? ? tb + X) = 0.68-0.35+0.38pb and ?(pp? ? tqb + X) = 2.86-0.63+0.69pb when assuming, respectively, tqb and tb production rates as predicted by the standard model.

  1. atomic mass measurement: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with small uncertainty allows us to predict properties of the as-yet-unobserved Higgs boson. This paper presents the status of the measurements of the top quark mass. A. P....

  2. atomic mass measurements: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with small uncertainty allows us to predict properties of the as-yet-unobserved Higgs boson. This paper presents the status of the measurements of the top quark mass. A. P....

  3. Search for Production of Heavy Particles Decaying to Top Quarks and Invisible Particles in pp[over-bar] Collisions at [sqrt]s=1.96??TeV

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present a search for a new particle T? decaying to top quark via T?-->t+X, where X is an invisible particle. In a data sample with 4.8??fb[superscript -1] of integrated luminosity collected by the CDF II detector at ...

  4. Azimuthal correlation between the $(\\vec{p}_l,\\vec{p}_{X_b})$ and $(\\vec{p}_l,\\vec{P}_t)$ planes in the semileptonic rest frame decay of a polarized top quark: An $O(?_s)$ effect

    E-Print Network [OSTI]

    S. Groote; W. S. Huo; A. Kadeer; J. G. Korner

    2008-02-25T23:59:59.000Z

    The azimuthal correlation between the planes formed by the vectors $(\\vec{p}_\\ell,\\vec{p}_{X_b})$ and $(\\vec{p}_\\ell,\\vec{P}_t)$ in the semileptonic rest frame decay of a polarized top quark $t(\\uparrow) \\to X_b + l^+ + \

  5. Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp[over-bar] Collisions at [sqrt]s=1.96??TeV

    E-Print Network [OSTI]

    Bauer, Gerry P.

    We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t-->Hb-->W[superscript (*)]a10b, and subsequently decaying into tau+tau-. Using a data sample corresponding to ...

  6. Determination of W boson helicity fractions in top quark decays in p anti-p collisions at CDF Run II and production of endcap modules for the ATLAS Silicon Tracker

    SciTech Connect (OSTI)

    Moed, Shulamit; /Geneva U.

    2007-01-01T23:59:59.000Z

    The thesis presented here includes two parts. The first part discusses the production of endcap modules for the ATLAS SemiConductor Tracker at the University of Geneva. The ATLAS experiment is one of the two multi-purpose experiments being built at the LHC at CERN. The University of Geneva invested extensive efforts to create an excellent and efficient module production site, in which 655 endcap outer modules were constructed. The complexity and extreme requirements for 10 years of LHC operation with a high resolution, high efficiency, low noise tracking system resulted in an extremely careful, time consuming production and quality assurance of every single module. At design luminosity about 1000 particles will pass through the tracking system each 25 ns. In addition to requiring fast tracking techniques, the high particle flux causes significant radiation damage. Therefore, modules have to be constructed within tight and accurate mechanical and electrical specification. A description of the ATLAS experiment and the ATLAS Semiconductor tracker is presented, followed by a detailed overview of the module production at the University of Geneva. My personal contribution to the endcap module production at the University of Geneva was taking part, together with other physicists, in selecting components to be assembled to a module, including hybrid reception tests, measuring the I-V curve of the sensors and the modules at different stages of the production, thermal cycling the modules and performing electrical readout tests as an initial quality assurance of the modules before they were shipped to CERN. An elaborated description of all of these activities is given in this thesis. At the beginning of the production period the author developed a statistics package which enabled us to monitor the rate and quality of the module production. This package was then used widely by the ATLAS SCT institutes that built endcap modules of any type, and kept being improved and updated. The production monitoring and summary using this package is shown in this thesis. The second part of the thesis reports a measurement of the fraction of longitudinal and right-handed helicity states of W bosons in top quark decays. This measurement was done using 955 pb{sup -1} of data collected with the CDF detector at the TEvatron, where protons and anti-protons are collided with a center-of-mass energy of 1.96 TeV. the helicity fraction measurements take advantage of the fact that the angular distribution of the W boson decay products depends on the helicity state of the W which they originate from. They analyze t{bar t} events in the 'lepton+jets' channel and look at the leptonic side of decay. They construct templates for the distribution of cos{theta}*, the angle between the charged lepton and the W flight direction in the rest frame of the top quark. Using Monte Carlo techniques, they construct probability distributions ('templates') for cos{theta}* in the case of left-handed, longitudinal and right-handed Ws and a template for the background model. They extract the W helicity fractions using an unbinned likelihood fitter based on the information of these templates. The Standard Model predicts the W helicity fractions to be about 70% longitudinal and 30% left-handed, while the fraction of right-handed W bosons in top decays is highly suppressed and vanishes when neglecting the mass of the b quark.

  7. Boosted top: experimental tools overview

    E-Print Network [OSTI]

    Emanuele Usai; for the ATLAS; CMS Collaborations

    2015-01-05T23:59:59.000Z

    An overview of tools and methods for the reconstruction of high-boost top quark decays at the LHC is given in this report. The focus is on hadronic decays, in particular an overview of the current status of top quark taggers in physics analyses is presented. The most widely used jet substructure techniques, normally used in combination with top quark taggers, are reviewed. Special techniques to treat pileup in large cone jets are described, along with a comparison of the performance of several boosted top quark reconstruction techniques.

  8. Keynote: Some remarks on top

    E-Print Network [OSTI]

    Werner Bernreuther

    2010-08-23T23:59:59.000Z

    A few key issues of present and future explorations of the physics of top quarks at the Tevatron and LHC are discussed.

  9. Top Polarization in Stop Production at the LHC

    E-Print Network [OSTI]

    G. Belanger; R. M. Godbole; L. Hartgring; I. Niessen

    2012-12-14T23:59:59.000Z

    We survey the expected polarization of the top produced in the decay of a scalar top quark, $\\tilde t \\rightarrow {\\tilde t}\\chi_i^0, i =1-2$. The phenomenology is quite interesting, since the expected polarization depends both on the mixing in the stop and neutralino sectors and on the mass differences between the stop and the neutralino. We find that a mixed stop behaves almost like a right-handed stop due to the larger hypercharge that enters the stop/top/gaugino coupling and that these polarisation effects disappear, when $m_{\\tilde t_1} \\approx m_t+m_{\\tilde\\chi^0_i}$. After a discussion on the expected top polarization from the decay of a scalar top quark, we focus on the interplay of polarization and kinematics at the LHC. We discuss different probes of the top polarization in terms of lab-frame observables. We find that these observables faithfully reflect the polarization of the parent top-quark, but also have a non-trivial dependence on the kinematics of the stop production and decay process. In addition, we illustrate the effect of top polarization on the energy and transverse momentum of the decay lepton in the laboratory frame. Our results show that both spectra are softened substantially in case of a negatively polarized top, particularly for a large mass difference between the stop and the neutralino. Thus, the search strategies, and the conclusions that can be drawn from them, depends not just on the mass difference $m_{\\tilde t} - m_{\\tilde\\chi_{i}^{0}}$ due to the usual kinematic effects but also on the effects of top polarization on the decay kinematics the extent of which depends in turn on the said mass difference.

  10. Mass spectrum of diquarks and mesons in the color--flavor locked phase of dense quark matter

    E-Print Network [OSTI]

    D. Ebert; K. G. Klimenko; V. L. Yudichev

    2007-09-25T23:59:59.000Z

    The spectrum of meson and diquark excitations of dense quark matter is considered in the framework of the Nambu -- Jona-Lasinio model with three types of massless quarks in the presense of a quark number chemical potential $\\mu$. We investigate the effective action of meson- and diquark fields both at sufficiently large values of $\\mu>\\mu_c\\approx 330$ MeV, where the color--flavor locked (CFL) phase is realized, and in the chirally broken phase of quark matter ($\\muphase the pseudoscalar diquarks are not allowed to exist as stable particles, but the scalar diquarks might be stable only at a rather strong interaction in the diquark channel. In the case of the CFL phase, all NG bosons of the model are realized as scalar and pseudoscalar diquarks. Moreover, it turns out that massive diquark excitations are unstable for this phase. In particular, for the scalar and pseudoscalar octets of diquark resonances a mass value around 230 MeV was found numerically. In contrast, mesons are stable particles in the CFL phase. Their masses lie in the interval 400$\\div$500 MeV for not too large values of $\\mu>\\mu_c$.

  11. Search for Single Top Production at the Tevatron

    SciTech Connect (OSTI)

    Gresele, Ambra; /INFN, Trento

    2006-05-01T23:59:59.000Z

    The authors report on a search for Standard Model t-channel and s-channel single top quark production in p{bar p} collisions at a center of mass energy of 1.96 TeV. The authors use a data sample corresponding to 0.7 fb{sup -1} recorded by the upgraded Collider Detector at Fermilab (CDFII) and a data sample corresponding to 370 pb{sup -1} recorded by D0. Both CDF and D0 find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section.

  12. Higgs as a Top-Mode Pseudo

    E-Print Network [OSTI]

    Hidenori S. Fukano; Masafumi Kurachi; Shinya Matsuzaki; Koichi Yamawaki

    2014-08-18T23:59:59.000Z

    In the spirit of the top quark condensation, we propose a model which has a naturally light composite Higgs boson, "tHiggs", to be identified with the 126 GeV Higgs discovered at the LHC. The tHiggs, a bound state of the top quark and its flavor (vector-like) partner, emerges as a pseudo Nambu-Goldstone boson (NGB), "Top-Mode Pseudo", together with the exact NGBs to be absorbed into the W and Z bosons as well as another (heavier) Top-Mode Pseudo (CP-odd composite scalar). Those five composite (exact/pseudo) NGBs are dynamically produced simultaneously by a single supercritical four-fermion interaction having U(3) x U(1) symmetry which includes the electroweak symmetry, where the vacuum is aligned by small explicit breaking term so as to break the symmetry down to a subgroup, U(2) x U(1)', in a way not to retain the electroweak symmetry, in sharp contrast to the little Higgs models. The explicit breaking term for the vacuum alignment gives rise to a mass of the tHiggs, which is protected by the symmetry and hence naturally controlled against radiative corrections. Realistic top quark mass is easily realized similarly to the top-seesaw mechanism by introducing an extra (subcritical) four-fermion coupling which explicitly breaks the residual U(2) x U(1)' symmetry. We present a phenomenological Lagrangian of the Top-Mode Pseudos along with the standard model particles, which will be useful for the study of the collider phenomenology. The coupling property of the tHiggs is shown to be consistent with the currently available data reported from the LHC. Several phenomenological consequences and constraints from experiments are also addressed.

  13. Measurements of single top quark production cross sections and |Vtb| in pp? collisions at ?s=1.96 TeV

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U., Augustana College, Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Aoki, Masato [Fermilab; Louisiana Tech U.

    2011-12-05T23:59:59.000Z

    We present measurements of production cross sections of single top quarks in pp? collisions at ?s = 1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of ?(pp? ? tb + X, tqb + X) = 3.43-0.74+0.73 pb and use it to extract the CKM matrix element 0.79 < |Vtb| {le} 1 at the 95% C.L. We also measure ?(pp? ? tb + X) = 0.68-0.35+0.38pb and ?(pp? ? tqb + X) = 2.86-0.63+0.69pb when assuming, respectively, tqb and tb production rates as predicted by the standard model.

  14. Measurement of associated production of vector bosons and top quark-antiquark pairs in pp collisions at ?s=7??TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Aguilo, E.; Bergauer, T.; Dragicevic, M.; Er, J.; Fabjan, C.; Friedl, M.; Frhwirth, R.; Ghete, V. M.; Hrmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knnz, V.; Krammer, M.; Krtschmer, I.; Liko, D.; Mikulec, I.; Pernicka, M.; Rabady, D.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schfbeck, R.; Strauss, J.; Taurok, A.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Bansal, M.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; DHondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hreus, T.; Lonard, A.; Marage, P. E.; Mohammadi, A.; Reis, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Sigamani, M.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Castello, R.; Ceard, L.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins Junior, M.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Ald Jnior, W. L.; Carvalho, W.; Chinellato, J.; Custdio, A.; Da Costa, E. M.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Malbouisson, H.; Malek, M.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Soares Jorge, L.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Anjos, T. S.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, Y.; Li, Q.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Zhang, L.; Zou, W.; Avila, C.; Carrillo Montoya, C. A.; Gomez, J. P.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Mekterovic, D.; Morovic, S.; Tikvica, L.; Attikis, A.; Galanti, M.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Kuotb Awad, A. M.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Mntel, M.; Murumaa, M.; Raidal, M.; Rebane, L.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Hrknen, J.; Heikkinen, A.; Karimki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampn, T.; Lassila-Perini, K.; Lehti, S.; Lindn, T.; Luukka, P.; Menp, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Korpela, A.; Tuuva, T.; Besancon, M.; Choudhury, S.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Millischer, L.; Nayak, A.; Rander, J.; Rosowsky, A.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dalchenko, M.; Dobrzynski, L.; Florent, A.; Granier de Cassagnac, R.; Haguenauer, M.; Min, P.; Mironov, C.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Fontaine, J.-C.; Gel, D.; Goerlach, U.; Juillot, P.; Le Bihan, A.-C.; Van Hove, P.; Beauceron, S.; Beaupere, N.; Bondu, O.; Boudoul, G.; Brochet, S.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sgandurra, L.; Sordini, V.; Tschudi, Y.; Verdier, P.; Viret, S.; Tsamalaidze, Z.; Autermann, C.

    2013-04-01T23:59:59.000Z

    The first measurement of vector-boson production associated with a top quark-antiquark pair in proton-proton collisions at ?s=7??TeV is presented. The results are based on a data set corresponding to an integrated luminosity of 5.0??fb?1 , recorded by the CMS detector at the LHC in 2011. The measurement is performed in two independent channels through a trilepton analysis of ttZ events and a same-sign dilepton analysis of ttV (V=W or Z ) events. In the trilepton channel a direct measurement of the ttZ cross section ?ttZ =0.28+0.14?0.11 ?(stat)+0.06?0.03 ?(syst)??pb is obtained. In the dilepton channel a measurement of the ttV cross section yields ?ttV =0.43+0.17?0.15 ?(stat)+0.09?0.07 ?(syst)??pb . These measurements have a significance, respectively, of 3.3 and 3.0 standard deviations from the background hypotheses and are compatible, within uncertainties, with the corresponding next-to-leading order predictions of 0.137+0.012?0.016 and 0.306+0.031?0.053??pb .

  15. Studies in hadron structure using lattice QCD with quark masses that almost reach the physical point

    E-Print Network [OSTI]

    Green, Jeremy Russell

    2013-01-01T23:59:59.000Z

    Lattice QCD allows us to study the structure of hadrons from first-principles calculations of quantum chromodynamics. We present calculations that shed light on the behavior of quarks inside hadrons in both qualitative and ...

  16. ASYMPTOTIC SAFETY, HYPERGEOMETRIC FUNCTIONS, AND THE HIGGS MASS IN SPECTRAL ACTION MODELS

    E-Print Network [OSTI]

    Marcolli, Matilde

    approximation that keeps only the dominant term in the Yukawa coupling matrices coming from the top quark Yukawa neutrinos with Majorana mass terms (MSM). We describe the usual approximations to the full system

  17. Model-Independent Production of a Top-Philic Resonance at the LHC

    E-Print Network [OSTI]

    Nicolas Greiner; Kyoungchul Kong; Jong-Chul Park; Seong Chan Park; Jan-Christopher Winter

    2014-10-22T23:59:59.000Z

    We investigate the collider phenomenology of a color-singlet vector resonance, which couples to the heaviest quarks, the top quarks, but very weakly to the rest of the fermions in the Standard Model. We find that the dominant production of such a resonance does not appear at the tree level -- it rather occurs at the one-loop level in association with an extra jet. Signatures like t anti-t plus jets readily emerge as a result of the subsequent decay of the resonance into a pair of top quarks. Without the additional jet, the resonance can still be produced off-shell, which gives a sizeable contribution at low masses. The lower top quark multiplicity of the loop induced resonance production facilitates its reconstruction as compared to the tree level production that gives rise to more exotic signatures involving three or even four top quarks in the final state. For all these cases, we discuss the constraints on the resonance production stemming from recent experimental measurements in the top quark sector. We find that the top-philic vector resonance remains largely unconstrained for the majority of the parameter space, although this will be scrutinized closely in the Run 2 phase of the LHC.

  18. Measurements of top quark pair production cross section in proton anti-proton collisions at s**(1/2) = 1.96 TeV in the tau + jets final state using 1 inv fb of data

    SciTech Connect (OSTI)

    Hossain, Sohrab; /Oklahoma U.

    2009-12-01T23:59:59.000Z

    This dissertation presents a new measurement of p{bar p} {yields} t{bar t}X production at {radical}s = 1.96 TeV using 974.2 pb{sup -1} of data collected with the D0 detector between 2002 and 2006. We focus on the final state where the W boson from one of the top quarks decays into a {tau} lepton and its associated neutrino, while the other W boson decays into a quark-antiquark pair. We aim to select those events in which the {tau} lepton subsequently decays hadronically, meaning to one or three charged hadrons, zero or more neutral hadrons and a tau neutrino (the charge conjugate processes are implied in all of the above). The observable signature thus consists of a narrow calorimeter shower with associated track(s) characteristic of a hadronic tau decay, four or more jets, of which two are initiated by b quarks accompanying the W's in the top quark decays, and a large net missing momentum in the transverse plane due to the energetic neutrino-antineutrino pair that leave no trace in the detector media. The preliminary result for the measured cross section is: {sigma}(t{bar t}) = 6.9{sub -1.2}{sup +1.2}(stat){sub -0.7}{sup +0.8}(syst) {+-} 0.4 (lumi) pb. This indicates that our finding is consistent with the Standard Model prediction.

  19. A Measurement of the production cross section of top-antitop pairs in proton-antiproton collisions at a center of mass of 1.96 TeV using secondary vertex b-tagging.

    SciTech Connect (OSTI)

    Bachacou, Henri

    2004-12-01T23:59:59.000Z

    A measurement of the t{bar t} pair production cross section is presented using 162 pb{sup -1} of data collected by the CDF experiment during Run II at the Tevatron. t{bar t} events in the lepton+jets channel are isolated by identifying electrons and muons, reconstructing jets and transverse missing energy, and identifying b jets with a secondary vertex tagging algorithm. The efficiency of the algorithm is measured in a control sample using a novel technique that is less dependent on the simulation. For a top quark mass of 175 GeV/c{sup 2}, a cross section of {sigma}{sub t{bar t}} = 5.6{sub -1.1}{sup +1.2}(stat.){sub -0.6}{sup +0.9}(syst.)pb is measured.

  20. Masses and Mixing Matrices of Families of Quarks and Leptons Within the Spin-Charge-Family theory, predictions beyond the tree level

    E-Print Network [OSTI]

    A. Hernandez-Galeana; N. S. Mankoc Borstnik

    2011-12-19T23:59:59.000Z

    The {\\it theory unifying spin and charges and predicting families}, proposed by N.S.M.B., predicts at the low energy regime two (in the mixing matrix elements decoupled) groups of four families. There are two kinds of contributions to mass matrices in this theory. One kind distinguishes on the tree level only among the members of one family, that is among the $u$-quark, $d$-quark, neutrino and electron, the left and right handed, while the other kind distinguishes only among the families. Mass matrices for $d$-quarks and electrons are on the tree level correspondingly strongly correlated and so are mass matrices for $u$-quarks and neutrinos, up to the term, the Majorana term, which is nonzero only for right handed neutrinos. Beyond the tree level both kinds of contributions start to contribute coherently and it is expected that a detailed study of properties of mass matrices beyond the tree level explains drastic differences in masses and mixing matrices between quarks and leptons. We report in this paper on analysis of one loop corrections to the tree level fermion masses and mixing matrices. Loop diagrams are mediated by the gauge bosons and the two kinds of scalar fields. A detailed numerical analysis of fermion masses and mixing, including neutrinos, within this scenario is in progress and preparation.

  1. Tools for top physics at D0

    E-Print Network [OSTI]

    Amnon Harel

    2008-07-24T23:59:59.000Z

    Top quark measurements rely on the jet energy calibration and often on b-quark identification. We discuss these and other tools and how they apply to top quark analyses at D0. In particular some of the nuances that result from D0's data driven approach to these issues are presented.

  2. Study of correlation of PDF uncertainty in single top and top pair production at the LHC

    E-Print Network [OSTI]

    The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    The incomplete knowledge of parton distribution functions is an important source of systematic uncertainty for top-quark measurements, including top-quark pair and single top-quark production cross sections, as well as for analyses that have a large background from these processes. The correlation of the parton-distribution-function uncertainty is studied for top-quark pair production and single top-quark production in association with a W boson, in final states with two reconstructed leptons. Four types of correlation are studied: between total production cross-sections, between cross-section and acceptance correction, between the two processes for common selection requirements, and between different jet multiplicity requirements. The uncertainty correlation is evaluated for several sets of parton distribution functions using simulated samples of top-quark pair and single top-quark events.

  3. Search for pair production of third-generation scalar leptoquarks and top squarks in proton-proton collisions at sqrt(s) = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan [Yerevan Physics Institute (Armeia); et al.,

    2014-12-01T23:59:59.000Z

    A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 inverse femtobarns, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100% branching fraction for the leptoquark decay to a tau lepton and a bottom quark. In addition, this mass limit applies directly to top squarks decaying via an R-parity violating coupling lambda'[333]. The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the R-parity violating coupling lambda'[3jk]. Each top squark decays to a tau lepton, a bottom quark, and two light quarks. Top squarks in this model with masses below 580 GeV are excluded at 95% confidence level. The constraint on the leptoquark mass is the most stringent to date, and this is the first search for top squarks decaying via lambda'[3jk].

  4. Search for pair production of third-generation scalar leptoquarks and top squarks in proton-proton collisions at sqrt(s) = 8 TeV

    E-Print Network [OSTI]

    CMS Collaboration

    2014-11-10T23:59:59.000Z

    A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 inverse femtobarns, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100% branching fraction for the leptoquark decay to a tau lepton and a bottom quark. In addition, this mass limit applies directly to top squarks decaying via an R-parity violating coupling lambda'[333]. The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the R-parity violating coupling lambda'[3jk]. Each top squark decays to a tau lepton, a bottom quark, and two light quarks. Top squarks in this model with masses below 580 GeV are excluded at 95% confidence level. The constraint on the leptoquark mass is the most stringent to date, and this is the first search for top squarks decaying via lambda'[3jk].

  5. Search for pair production of third-generation scalar leptoquarks and top squarks in proton-proton collisions at sqrt(s) = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan; et al.,

    2014-12-01T23:59:59.000Z

    A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 inverse femtobarns, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100% branching fraction for the leptoquark decaymoreto a tau lepton and a bottom quark. In addition, this mass limit applies directly to top squarks decaying via an R-parity violating coupling lambda'[333]. The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the R-parity violating coupling lambda'[3jk]. Each top squark decays to a tau lepton, a bottom quark, and two light quarks. Top squarks in this model with masses below 580 GeV are excluded at 95% confidence level. The constraint on the leptoquark mass is the most stringent to date, and this is the first search for top squarks decaying via lambda'[3jk].less

  6. Broken Valence Chiral Symmetry and Chiral Polarization of Dirac Spectrum in N$_f$=12 QCD at Small Quark Mass

    E-Print Network [OSTI]

    Andrei Alexandru; Ivan Horvth

    2014-12-04T23:59:59.000Z

    The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass-degenerate fundamental quark flavors. We find that the vSChSB-ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass $m_c$ such that for $m > m_c$ the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for $m_{ch} < m < m_c$ the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses $m < m_{ch}$, but this has not yet been seen by overlap valence probe, leaving the $m_{ch}=0$ possibility open. The latter option could place massless N$_f$=12 theory outside of conformal window. Anomalous behavior of overlap Dirac spectrum for $m_{ch} < m < m_c$ is qualitatively similar to one observed previously in zero and few-flavor theories as an effect of thermal agitation.

  7. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan [Yerevan Physics Institute (Armenia)

    2014-09-01T23:59:59.000Z

    A measurement of the cross section for the production of top quarkantiquark pairs ( ${\\mathrm {t}}\\overline{{\\mathrm {t}}}$ ) in association with a vector boson V (W or Z) in proton-proton collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$ is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb$^{-1}$ recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and $\\mu$) channels: a same-sign dilepton analysis targeting ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ events, and trilepton and four-lepton analyses designed for ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ events. In the same-sign dilepton channel, the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ cross section is measured as $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W}} = 170 ^{+90-80}\\,\\text {(stat)} \\pm 70\\,\\text {(syst)} \\, \\text {fb} $ , corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ cross section, $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}}} = 200 ^{+80-70}\\,\\text {(stat)} ^{+40-30}\\,\\text {(syst)} \\mathrm{fb}^{-1} $ , is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {V}} $ process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.

  8. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-09-01T23:59:59.000Z

    A measurement of the cross section for the production of top quarkantiquark pairs ( ${\\mathrm {t}}\\overline{{\\mathrm {t}}}$ ) in association with a vector boson V (W or Z) in proton-proton collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$ is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb$^{-1}$ recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and $\\mu$) channels: a same-sign dilepton analysis targeting ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ events, and trilepton and four-lepton analyses designed for ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ events. Inmorethe same-sign dilepton channel, the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ cross section is measured as $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W}} = 170 ^{+90-80}\\,\\text {(stat)} \\pm 70\\,\\text {(syst)} \\, \\text {fb} $ , corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ cross section, $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}}} = 200 ^{+80-70}\\,\\text {(stat)} ^{+40-30}\\,\\text {(syst)} \\mathrm{fb}^{-1} $ , is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {V}} $ process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.less

  9. anomalous single top: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    angular correlation and the amount of top quark polarization in the production of a higgs boson in association with a single top quark in the t-channel at the LHC. We also study...

  10. Recent Top Properties Measurements at CDF

    E-Print Network [OSTI]

    Giorgio Chiarelli

    2014-10-09T23:59:59.000Z

    We present the most recent CDF results in the measurements of the decay and production vertex of the top-quark. New results on forward-backward asymmetry in top-antitop events are presented. Also, recent measurements of the branching fractions of top-quark are discussed. Finally, measurements in single top events, where top-quark is produced through electroweak processes, are presented. Despite the much larger number of top events collected at the LHC, due to the symmetric initial state and the better signal-to-background ratio in specific channels, some results will be lasting heritage of the Tevatron.

  11. Top Jets at the LHC

    E-Print Network [OSTI]

    Almeida, L.G.

    2009-01-01T23:59:59.000Z

    Top Jets at the LHC Leandro G. Almeida, Seung J. Lee, GiladSB-08-37; WIS/17/08-SEPT-DPP Top Jets at the LHC Leandro G.p T hadronically-decaying top quarks at the Large Hadron

  12. Masses and Mixing Matrices of Families of Quarks and Leptons Within the Spin-Charge-Family theory, predictions beyond the tree level

    E-Print Network [OSTI]

    Hernandez-Galeana, A

    2011-01-01T23:59:59.000Z

    The {\\it theory unifying spin and charges and predicting families}, proposed by N.S.M.B., predicts at the low energy regime two (in the mixing matrix elements decoupled) groups of four families. There are two kinds of contributions to mass matrices in this theory. One kind distinguishes on the tree level only among the members of one family, that is among the $u$-quark, $d$-quark, neutrino and electron, the left and right handed, while the other kind distinguishes only among the families. Mass matrices for $d$-quarks and electrons are on the tree level correspondingly strongly correlated and so are mass matrices for $u$-quarks and neutrinos, up to the term, the Majorana term, which is nonzero only for right handed neutrinos. Beyond the tree level both kinds of contributions start to contribute coherently and it is expected that a detailed study of properties of mass matrices beyond the tree level explains drastic differences in masses and mixing matrices between quarks and leptons. We report in this paper on ...

  13. Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass

    E-Print Network [OSTI]

    ZEUS collaboration; H. Abramowicz; I. Abt; L. Adamczyk; M. Adamus; R. Aggarwal; S. Antonelli; O. Arslan; V. Aushev; Y. Aushev; O. Bachynska; A. N. Barakbaev; N. Bartosik; O. Behnke; J. Behr; U. Behrens; A. Bertolin; S. Bhadra; I. Bloch; V. Bokhonov; E. G. Boos; K. Borras; I. Brock; R. Brugnera; A. Bruni; B. Brzozowska; P. J. Bussey; A. Caldwell; M. Capua; C. D. Catterall; J. Chwastowski; J. Ciborowski; R. Ciesielski; A. M. Cooper-Sarkar; M. Corradi; F. Corriveau; G. D'Agostini; R. K. Dementiev; R. C. E. Devenish; G. Dolinska; V. Drugakov; S. Dusini; J. Ferrando; J. Figiel; B. Foster; G. Gach; A. Garfagnini; A. Geiser; A. Gizhko; L. K. Gladilin; O. Gogota; Yu. A. Golubkov; J. Grebenyuk; I. Gregor; G. Grzelak; O. Gueta; M. Guzik; W. Hain; G. Hartner; D. Hochman; R. Hori; Z. A. Ibrahim; Y. Iga; M. Ishitsuka; A. Iudin; F. Januschek; I. Kadenko; S. Kananov; T. Kanno; U. Karshon; M. Kaur; P. Kaur; L. A. Khein; D. Kisielewska; R. Klanner; U. Klein; N. Kondrashova; O. Kononenko; Ie. Korol; I. A. Korzhavina; A. Kota?ski; U. Ktz; N. Kovalchuk; H. Kowalski; O. Kuprash; M. Kuze; B. B. Levchenko; A. Levy; V. Libov; S. Limentani; M. Lisovyi; E. Lobodzinska; W. Lohmann; B. Lhr; E. Lohrmann; A. Longhin; D. Lontkovskyi; O. Yu. Lukina; J. Maeda; I. Makarenko; J. Malka; J. F. Martin; S. Mergelmeyer; F. Mohamad Idris; K. Mujkic; V. Myronenko; K. Nagano; A. Nigro; T. Nobe; D. Notz; R. J. Nowak; K. Olkiewicz; Yu. Onishchuk; E. Paul; W. Perla?ski; H. Perrey; N. S. Pokrovskiy; A. S. Proskuryakov; M. Przybycie?; A. Raval; P. Roloff; I. Rubinsky; M. Ruspa; V. Samojlov; D. H. Saxon; M. Schioppa; W. B. Schmidke; U. Schneekloth; T. Schrner-Sadenius; J. Schwartz; L. M. Shcheglova; R. Shehzadi; R. Shevchenko; O. Shkola; I. Singh; I. O. Skillicorn; W. S?omi?ski; V. Sola; A. Solano; A. Spiridonov; L. Stanco; N. Stefaniuk; A. Stern; T. P. Stewart; P. Stopa; J. Sztuk-Dambietz; D. Szuba; J. Szuba; E. Tassi; T. Temiraliev; K. Tokushuku; J. Tomaszewska; A. Trofymov; V. Trusov; T. Tsurugai; M. Turcato; O. Turkot; T. Tymieniecka; A. Verbytskyi; O. Viazlo; R. Walczak; W. A. T. Wan Abdullah; K. Wichmann; M. Wing; G. Wolf; S. Yamada; Y. Yamazaki; N. Zakharchuk; A. F. ?arnecki; L. Zawiejski; O. Zenaiev; B. O. Zhautykov; N. Zhmak; D. S. Zotkin

    2014-10-21T23:59:59.000Z

    The production of beauty and charm quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared 5 < Q^2 < 1000 GeV^2 using an integrated luminosity of 354 pb^{-1}. The beauty and charm content in events with at least one jet have been extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of Q^2, Bjorken x, jet transverse energy and pseudorapidity were measured and compared with next-to-leading-order QCD calculations. The beauty and charm contributions to the proton structure functions were extracted from the double-differential cross section as a function of x and Q^2. The running beauty-quark mass, m_b at the scale m_b, was determined from a QCD fit at next-to-leading order to HERA data for the first time and found to be 4.07 \\pm 0.14 (fit} ^{+0.01}_{-0.07} (mod.) ^{+0.05}_{-0.00} (param.) ^{+0.08}_{-0.05} (theo) GeV.

  14. B-jet and c-jet identification with Neural Networks as well as combination of multivariate analyses for the search for of multivariate analyses for the search for single top-quark production

    SciTech Connect (OSTI)

    Renz, Manuel; /Karlsruhe U., EKP

    2008-06-01T23:59:59.000Z

    In the first part of this diploma thesis, the current version of the KIT Flavor Separator, a neural network which is able to distinguish between tagged b-quark jets and tagged c/light-quark jets, is presented. In comparison with previous versions four new input variables are utilized and new Monte Carlo samples with a larger number of simulated events are used for the training of the neural network. It is illustrated that the output of the neural network is continuously distributed between 1 and -1, whereas b-quark jets accumulate at 1, however, c-quark jets and light-quark jets have outputs next to -1. To ensure that the network output describes observed events correctly, the shapes of all input variables are compared in simulation and data. Thus the mismodelling of any input variable is excluded. Moreover, the b jet and light jet output distributions are compared with the output of samples of observed events, which are enhanced in the particular flavor. In contrast to previous versions, no b-jet output correction function has to be calculated, because the agreement between simulation and collision data is excellent for b-quark jets. For the light-jet output, correction functions are developed. Different applications of the KIT Flavor Separator are mentioned. For example it provides a precious input to all three CDF single top quark analyses. Furthermore, it is shown that the KIT Flavor Separator is a universal tool, which can be used in every high-p{sub T} analysis that requires the identification of b-quark jets with high efficiency. As it is pointed out, a further application is the estimation of the flavor composition of a given sample of observed events. In addition a neural network, which is able to separate c-quark jets from light-quark jets, is trained. It is shown, that all three flavors can be separated in the c-net-Flavor Separator plane. As a result, the uncertainties on the estimation of the flavor composition in events with one tagged jet are cut into half. In the second part of this diploma thesis, a method for the combination of three multivariate single-top analyses using an integrated luminosity of 2.2 fb{sup -1} is presented. For this purpose the discriminants of the Likelihood Function analysis, the Matrix Element method and the Neural Network analysis are used as input variables to a neural network. Overall four different networks are trained, one for events with two or three jets and one or two SecVtx tags, respectively. Using a binned likelihood function, the outputs of these networks are fitted to the output distribution of observed events. A single top-quark production cross section of {sigma}{sub single-top} = 2.2{sub -0.7}{sup +0.8} pb is measured. Ensemble tests are performed for the calculation of the sensitivity and observed significance, which are found to be 4.8{sigma} and 3.9{sigma}, respectively. Hence the improvement of this combination is roughly 8% in comparison with sensitivities found by the individual analyses. Due to the proportionality of {sigma}{sub single-top} and |V{sub tb}|{sup 2} and under the assumption V{sub tb} >> V{sub ts}, V{sub td}, a value for |V{sub tb}| is quoted: |V{sub tb}| = 0.88{sub -0.12}{sup +0.14}(exp.) {+-} 0.07(theo.). It can be seen, that the given uncertainties are too large for a verification or falsification of the unitarity assumption of the CKM-matrix. Parallel to this combination a further combination method (NEAT-combination) has been developed. This combination uses a neural network trained with a neuroevolution technique, which optimizes the neural network architecture and weights through the use of genetic algorithms. In this analysis an improvement of roughly 12% could be reached. In figure 7.1 the current situation for the measurement of the single top-quark production cross section is summarized. After collecting more data, CDF will be able to observe single top-quark production with a significance larger than 5.0{sigma}. Nevertheless, the cross section measurement will still have large uncertainties on the level of 20%. Precise measure

  15. The role of top in heavy flavor physics

    SciTech Connect (OSTI)

    Hewett, J.L. [Stanford Linear Accelerator Center, Stanford, CA (United States)

    1997-01-01T23:59:59.000Z

    The implications of the massive top quark on heavy flavor transitions are explored. We review the generation of quark masses and mixings and the determination techniques, and present the status of the elements of the weak mixing matrix. Purely leptonic decays of heavy mesons are briefly summarized. We present a general introduction to flavor changing neutral currents and an extensive summary of radiative and other rare decay modes. The physics of neutral meson mixing is reviewed and applied to each meson system. We describe the phenomenology of CP violation and how it may be measured in meson decays. Standard Model predictions are given in each case and the effects of physics beyond the Standard Model are also discussed. Throughout, we contrast these transitions in the K and B meson systems to those in the D meson and top-quark sectors.

  16. Can the four-zero-texture mass matrix model reproduce the observed quark and lepton mixing angles and CP-violating phases?

    SciTech Connect (OSTI)

    Matsuda, Koichi; Nishiura, Hiroyuki [Center for High Energy Physics, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Faculty of Information Science and Technology, Osaka Institute of Technology, Hirakata, Osaka 573-0196 (Japan)

    2006-08-01T23:59:59.000Z

    We reconsider a universal mass matrix model which has a seesaw-invariant structure with four-zero texture common to all quarks and leptons. The Cabibbo-Kobayashi-Maskawa (CKM) quark and Maki-Nakagawa-Sakata (MNS) lepton mixing matrices of the model are analyzed analytically. We show that the model can be consistent with all the experimental data of neutrino oscillation and quark mixings by tuning free parameters of the model. It is also shown that the model predicts a relatively large value for the (1, 3) element of the MNS lepton mixing matrix (U{sub MNS}){sub 13}{sup 2}{approx_equal}(0.041-9.6)x10{sup -2}. Using the seesaw mechanism, we also discuss the conditions for the components of the Dirac and the right-handed Majorana neutrino mass matrices which lead to the neutrino mass matrix consistent with the experimental data.

  17. Simultaneous measurement of the ratio B(t->Wb)/B(t->Wq) and the top quark pair production cross section with the D0 detector at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Simon Fraser U.; Ahn, S.H.; /Korea U., KODEL; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP /Michigan U.

    2008-01-01T23:59:59.000Z

    The authors present the first simultaneous measurement of the ratio of branching fractions, R = {Beta}(t {yields} Wb)/{Beta}(t {yields} Wq), with q being a d, s, or b quark, and the top quark pair production cross section {sigma}{sub t{bar t}} in the lepton plus jets channel using 0.9 fb{sup -1} of p{bar p} collision data at {radical}s = 1.96 TeV collected with the D0 detector. they extract R and {sigma}{sub t{bar t}} by analyzing samples of events with 0, 1 and {ge} 2 identified b jets. They measure R = 0.97{sub -0.08}{sup +0.09} (stat+syst) and {sigma}{sub t{bar t}} = 8.18{sub -0.84}{sup +0.90}(stat+syst) {+-} 0.50 (lumi) pb, in agreement with the standard model prediction.

  18. Determination of the pole and (MS)-bar masses of the top quark from the tt-bar cross section

    E-Print Network [OSTI]

    Baringer, Philip S.; Bean, Alice; Carrasco-Lizarraga, M. A.; Chen, G.; Clutter, Justace Randall; McGivern, Carrie Lynne; Sekaric, Jadranka; Wilson, Graham Wallace; D0 Collaboration; Abazov, V. M.; Abbott, B.; Acharya, B.S.; Adams, M.; Adams, T.

    2011-09-20T23:59:59.000Z

    , Marseille, France AL, Universit Paris-Sud, CNRS/IN2P3, Orsay, France PNHE, Universits Paris VI and VII, CNRS/IN2P3, Paris, France EA, Irfu, SPP, Saclay, France PHC, Universit de Strasbourg, CNRS/IN2P3, Strasbourg, France PNL, Universit Lyon 1, CNRS/IN2P3...

  19. Top partner probes of extended Higgs sectors

    E-Print Network [OSTI]

    Kearney, John

    Natural theories of the weak scale often include fermionic partners of the top quark. If the electroweak symmetry breaking sector contains scalars beyond a single Higgs doublet, then top partners can have sizable branching ...

  20. Magnetic susceptibility and equation of state of N_f = 2+1 QCD with physical quark masses

    E-Print Network [OSTI]

    Claudio Bonati; Massimo D'Elia; Marco Mariti; Francesco Negro; Francesco Sanfilippo

    2014-05-13T23:59:59.000Z

    We determine the free energy of strongly interacting matter as a function of an applied constant and uniform magnetic field. We consider N_f = 2+1 QCD with physical quark masses, discretized on a lattice by stout improved staggered fermions and a tree level improved Symanzik pure gauge action, and explore three different lattice spacings. For magnetic fields of the order of those produced in non-central heavy ion collisions (eB ~ 0.1 GeV^2) strongly interacting matter behaves like a medium with a linear response, and is paramagnetic both above and below the deconfinement transition, with a susceptibility which steeply rises in the deconfined phase. We compute the equation of state, showing that the relative increase in the pressure due to the magnetic field gets larger around the transition, and of the order of 10 % for eB ~ 0.1 GeV^2.

  1. Interpretations and implications of the top quark rapidity asymmetries A FB t and A FB ?

    SciTech Connect (OSTI)

    Berger, Edmond L.; Cao, Qing-Hong; Chen, Chuan-Ren; Zhang, Hao

    2013-07-01T23:59:59.000Z

    Forward-backward asymmetries AtFB and AlFB are observed in the top-quark t rapidity distribution and in the rapidity distribution of charged leptons l from top-quark decay at the Tevatron proton-antiproton collider, and a charge asymmetry AC is seen in proton-proton collisions at the Large Hadron Collider (LHC). In this paper, we update our previous studies of the Tevatron asymmetries using the most recent data. We provide expectations for AC at the LHC based first on simple extrapolations from the Tevatron, and second based on new physics models that can explain the Tevatron asymmetries. We examine the relationship of the two asymmetries AtFB and AlFB. We show their connection through the (VA) spin correlation between the charged lepton and the top quark with different polarization states. We show that the ratio of the two asymmetries provides independent insight into the physics interpretation of the top-quark asymmetry. We emphasize the value of the measurement of both asymmetries, and we conclude that a model which produces more right-handed than left-handed top quarks is suggested by the present Tevatron data.

  2. Quark mass uncertainties revive Kim-Shifman-Vainshtein-Zakharov axion dark matter

    E-Print Network [OSTI]

    Buckley, Matthew R.; Murayama, Hitoshi

    2007-01-01T23:59:59.000Z

    mass uncertainties revive KSVZ axion dark matter Matthew R.bounds on the QCD axion, speci?cally KSVZ axions in the 2 ?particles. The as-yet-unseen axion, origi- nally proposed to

  3. Vector screening masses in the quark-gluon plasma and their physical significance

    E-Print Network [OSTI]

    B. B. Brandt; A. Francis; M. Laine; H. B. Meyer

    2014-08-25T23:59:59.000Z

    Static and non-static thermal screening states that couple to the conserved vector current are investigated in the high-temperature phase of QCD. Their masses and couplings to the current are determined at weak coupling, as well as using two-flavor lattice QCD simulations. A consistent picture emerges from the comparison, providing evidence that non-static Matsubara modes can indeed be treated perturbatively. We elaborate on the physical significance of the screening masses.

  4. Search for Production of Heavy Particles Decaying to Top Quarks and Invisible Particles in $p\\bar{p}$ collisions at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Apresyan, A.; /Purdue U.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-03-01T23:59:59.000Z

    We present a search for a new particle T{prime} decaying to a top-quark via T{prime} {yields} t + X, where X is an invisible particle. In a data sample with 4.8 fb{sup -1} of integrated luminosity collected by the CDF II detector at Fermilab in p{bar p} collisions with {radical}s = 1.96 TeV, we search for pair production of T0 in the lepton+jets channel, p{bar p} {yields} t{bar t} + XX {yields} {ell}{nu}bqq{prime}b + XX. We interpret our results primarily in terms of a model where T{prime} are exotic fourth generation quarks and X are dark matter particles. The data are consistent with standard model expectations, and we set 95% confidence level limits on the generic production of T{prime}{bar T}{prime} {yields} t{bar t} + XX. We apply these limits to the dark matter model and exclude the fourth generation exotic quarks T{prime} at 95% confidence level up to m{sub T{prime}} = 360 GeV/c{sup 2} for m{sub x} {<=} 100 GeV/c{sup 2}.

  5. Protein Identification Using Top-Down. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Identification Using Top-Down. Protein Identification Using Top-Down. Abstract: In the last two years, due to advances in protein separation and mass spectrometry, top-down mass...

  6. Quark-antiquark bound-state spectroscopy and QCD

    SciTech Connect (OSTI)

    Bloom, E.D.

    1982-11-01T23:59:59.000Z

    The discussion covers quarks as we know them, the classification of ordinary mesons in terms of constituent quarks, hidden charm states and charmed mesons, bottom quarks, positronium as a model for quarti q, quantum chromodynamics and its foundation in experiment, the charmonium model, the mass of states, fine structure and hyperfine structure, classification, widths of states, rate and multipolarity of gamma transitions, questions about bottom, leptonic widths and the determination of Q/sub b/, the mass splitting of the n/sup 3/S/sub 1/ states, the center of gravity of the masses of the n/sup 3/P; states, n/sup 3/ P; fine structure and classification, branching ratios for upsilon' ..-->.. tau chi/sub 6j/ and the tau cascade reactions, hyperfine splitting, and top. (GHT)

  7. PoS(TOP2006)026 Top properties within the SM

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    PoS(TOP2006)026 Top properties within the SM Bernardo Resende CPPM, CNRS/IN2P3 - Univ. Méditerranée, Marseille, France E-mail: resende@cppm.in2p3.fr The high number of top quarks which Workshop on Top Quark Physics January 12-15, 2006 Coimbra, Portugal ¡ On behalf of the CMS and ATLAS

  8. Top polarisation measurement and anomalous $Wtb$ coupling

    E-Print Network [OSTI]

    Arun Prasath; Rohini M. Godbole; Saurabh D. Rindani

    2014-12-09T23:59:59.000Z

    Kinematical distributions of the decay products of the top quark carry information on the polarisation of the top as well as on any possible new physics in the decay of the top quark. We construct observables in the form of asymmetries in the kinematical distributions to probe their effects. Charged-lepton angular distributions in the decay are insensitive to anomalous couplings and are a sensitive measure of top polarisation. However, these are difficult to measure in the case of highly boosted top quarks as compared to energy distributions of decay products. These are then sensitive, in general, to both top polarisation and top anomalous couplings. We compare various asymmetries for their sensitivities to the polarisation of the top quark as well as to possible new physics in the $Wtb$ vertex, paying special attention to the case of highly boosted top quarks. We perform a $\\chi ^2$- analysis to determine the regions in the polarisation of the top quark and the couplings of the $Wtb$ vertex constrained by different combinations of the asymmetries.

  9. Top Jets in the Peak Region: Factorization Analysis with NLL Resummation

    E-Print Network [OSTI]

    Sean Fleming; Andre H. Hoang; Sonny Mantry; Iain W. Stewart

    2008-05-31T23:59:59.000Z

    We consider top-quarks produced at large energy in e+e- collisions, and address the question of what top-mass can be measured from reconstruction. The production process is characterized by well separated scales: the center-of-mass energy, Q, the top mass, m, the top decay width, Gamma_t, and also LambdaQCD; scales which can be disentangled with effective theory methods. In particular we show how the mass measurement depends on the way in which soft radiation is treated, and that this can shift the mass peak by an amount of order Q LambdaQCD/m. We sum large logs for Q >> m >> Gamma_t > LambdaQCD and demonstrate that the renormalization group ties together the jet and soft interactions below the scale m. Necessary conditions for the invariant mass spectrum to be protected from large logs are formulated. Results for the cross-section are presented at next-to-leading order with next-to-leading-log resummation, for invariant masses in the peak region and the tail region. Using our results we also predict the thrust distribution for massive quark jets at NLL order for large thrust. We demonstrate that soft radiation can be precisely controlled using data on massless jet production, and that in principle, a short distance mass parameter can be measured using jets with precision better than LambdaQCD.

  10. Mass spectrum of diquarks and mesons in the color--flavor locked phase of dense quark matter

    E-Print Network [OSTI]

    Ebert, D; Yudichev, V L

    2007-01-01T23:59:59.000Z

    The spectrum of meson and diquark excitations of dense quark matter is considered in the framework of the Nambu -- Jona-Lasinio model with three types of massless quarks in the presense of a quark number chemical potential $\\mu$. We investigate the effective action of meson- and diquark fields both at sufficiently large values of $\\mu>\\mu_c\\approx 330$ MeV, where the color--flavor locked (CFL) phase is realized, and in the chirally broken phase of quark matter ($\\mu\\mu_c$.

  11. Electroweak and top physics at CDF in Run II

    SciTech Connect (OSTI)

    A. Taffard

    2003-06-12T23:59:59.000Z

    The CDF experiment at the Tevatron has used p{bar p} collisions at {radical}s = 1.96 TeV to measure the production cross sections of W and Z bosons using several leptonic final states. An indirect measurement of the W width and the ratio of tau and electron electroweak couplings have been extracted. The forward-backward charge asymmetry, A{sub FB}, in Drell-Yan dilectron production has been measured up to an invariant mass of 600 GeV/c{sup 2}. CDF has also started looking for WW production in the dilepton channel, WW{prime} {yields} ll{prime}vv, with the aim of measuring its cross section and derive limits on the anomalous WWZ and WW{gamma} couplings. The presence of a top quark signal in the Tevatron data has been reestablished by measuring the top quark pair production cross section in the dilepton channel, t{bar t} {yields} WbW{bar b} {yields} {bar l}v{sub l}bl{prime}{bar v}{sub l{prime}}{bar b} and in the lepton plus jets channel, t{bar t} {yields} WbW{bar b} {yields} q{bar q}lbl{bar b}{sub l}{bar b} + {bar l}v{sub l}bq{bar q}{prime}{bar b}. A pre-tagged lepton plus jets sample has also been used to reconstruct the top quark mass.

  12. Analyzing the scalar top co-annihilation region at the ILC

    SciTech Connect (OSTI)

    Carena, M.; /Fermilab; Finch, A.; /Lancaster U.; Freitas, A.; Milstene, C.; /Fermilab; Nowak, H.; /DESY, Zeuthen; Sopczak, A.; /Lancaster U.

    2005-08-01T23:59:59.000Z

    The Minimal Supersymmetric Standard Model opens the possibility of electroweak baryogenesis provided that the light scalar top quark (stop) is lighter than the top quark. In addition, the lightest neutralino is an ideal candidate to explain the existence of dark matter. For a light stop with mass close to the lightest neutralino, the stop-neutralino co-annihilation mechanism becomes efficient, thus rendering the predicted dark matter density compatible with observations. Such a stop may however remain elusive at hadron colliders. Here it is shown that a future linear collider provides a unique opportunity to detect and study the light stop. The production of stops with small stop-neutralino mass differences is studied in a detailed experimental analysis with a realistic detector simulation including a CCD vertex detector for flavor tagging. Furthermore, the linear collider, by precision measurements of superpartner masses and mixing angles, also allows to determine the dark matter relic density with an accuracy comparable to recent astrophysical observations.

  13. Quark Condensates: Flavour Dependence

    E-Print Network [OSTI]

    R. Williams; C. S. Fischer; M. R. Pennington

    2007-03-23T23:59:59.000Z

    We determine the q-bar q condensate for quark masses from zero up to that of the strange quark within a phenomenologically successful modelling of continuum QCD by solving the quark Schwinger-Dyson equation. The existence of multiple solutions to this equation is the key to an accurate and reliable extraction of this condensate using the operator product expansion. We explain why alternative definitions fail to give the physical condensate.

  14. Top production at the LHC

    E-Print Network [OSTI]

    Kanzaki, Junichi; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    Measurements of the inclusive top quark production cross sections in proton-proton collisions with the ATLAS and CMS detectors at the Large Hadron Collider are presented. The measurements of the precise pair production cross section are performed for di-lepton, semi-leptonic and hadronic final states. Differential measurements of the top transverse momentum and kinematic properties of the top-anti-top pair are also discussed. The results, unfolded to particle and parton level, are compared to recent Monte Carlo generators implementing LO and NLO matrix elements matched with parton showers and NLO QCD calculations. For single top-quark productions cross sections are measured for t-channel, s-channel and W-boson associated production processes. The single top-quark and anti-top total production cross sections, their ratio, as well as a measurement of the inclusive production cross section is presented. All measurements are compared to theoretical calculations and the CKM matrix element |Vtb| is determined.

  15. Does $K_L-K_S$ mass difference constraints or \\\\ claims new physics beyond the Standard Model?

    E-Print Network [OSTI]

    F. Pisano; V. Pleitez

    1993-08-16T23:59:59.000Z

    The ratio $\\Delta m_K/m_K$ within the standard model with 3 generations is calculated as a function of the CP nonconserving phase $\\delta_{13}$ and the quark masses $m_c,m_t$ assuming the current values of the Cabibbo-Kobayashi-Maskawa mixing angles. We have found that varying $\\delta_{13}$ and $m_c$ within the allowed range, not all the values for the top quark mass fit the experimental value for that ratio.

  16. Charm Quark Energy Loss in QCD Matter

    E-Print Network [OSTI]

    W. C. Xiang; H. T. Ding; D. C. Zhou; D. Rohrich

    2005-07-13T23:59:59.000Z

    The energy loss of heavy quarks in a quark-gluon plasma of finite size is studied within the light-cone integral approach. A simple analytical formulation of the radiative energy loss of heavy quarks is derived. This provides a convenient way to quantitatively estimate the quark energy loss. Our results show that if the energy of a heavy quark is much larger than its mass, the radiative energy loss approaches the radiative energy loss of light quarks.

  17. Measurement of the single top production cross section in proton-antiproton collisions at 1.96 TeV

    SciTech Connect (OSTI)

    Tanasijczuk, Andres Jorge; /Buenos Aires U.

    2010-05-01T23:59:59.000Z

    This thesis describes a search for singly produced top quarks via an electroweak vertex in head-on proton-antiproton collisions at a center of mass energy of {radical}s = 1.96 TeV. The analysis uses a total of 2.3 fb{sup -1} of data collected with the D0 detector at Fermilab, corresponding to two different run periods of the Tevatron collider. Two channels contribute to single top quark production at the Tevatron, the s-channel and the t-channel. In the s-channel, a virtual W boson is produced from the aniquilation of a quark and an antiquark and a top and a bottom quarks are produced from the W decay. The top quark decays almost exclusively into a W boson and a bottom quark. Final states are considered in which the W boson decays leptonically into an electron or a muon plus a neutrino. Thus, at the detector level, the final state characterizing the s-channel contains one lepton, missing energy accounting for the neutrino, and two jets from the two bottom quarks. In the t-channel, the final state has an additional jet coming from a light quark. Clearly, a precise reconstruction of the events requires a precise measurement of the energy of the jets. A multivariate technique, Bayesian neural networks, is used to extract the single top signal from the overwhelming background still left after event selection. A Bayesian likelihood probability is then computed to measure the single top cross section. Assuming the observed excess is due to single top events, the measured single top quark production cross section is {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.70{sub -0.93}{sup +1.18} pb. The observed excess is associated with a p-value of (3.2 {+-} 2.3) x 10{sup -8}, assuming the background-only hypothesis. This p-value corresponds to an excess over background of 5.4 standard deviations for a Gaussian density. The p-value computed using the standard model signal cross section of 3.46 pb is (22.7 {+-} 0.6) x 10{sup -6}, corresponding to an expected significance of 4.08 standard deviations.

  18. Variational Analysis of Mass Spectra and Decay Constants for Ground State Pseudoscalar and Vector Mesons in Light-Front Quark Model

    E-Print Network [OSTI]

    Choi, Ho-Meoyng; Li, Ziyue

    2015-01-01T23:59:59.000Z

    Using the variational principle, we compute mass spectra and decay constants of ground state pseudoscalar and vector mesons in the light-front quark model with the QCD-motivated effective Hamiltonian including the hyperfine interaction. By smearing out the Dirac delta function in the hyperfine interaction, we avoid the issue of negative infinity in applying the variational principle to the computation of meson mass spectra. In comparison with the previous computation handling the hyperfine interaction as perturbation, our variational analysis provides an overall improvement on the agreement with the experimental data of mass spectra for the ground state pseudoscalar and vector mesons from $\\pi$ to $\\Upsilon$. By taking a larger harmonic oscillator basis in our trial wave function, we also obtain the better agreement between the experimental data of decay constants and the results from our model calculation for these mesons.

  19. Measurement of the t-channel single-top-quark production cross section and of the |Vtb| CKM matrix element in pp collisions at sqrt(s) = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, V. [Yerevan Physics Institute (Armenia); et al.,

    2014-06-01T23:59:59.000Z

    Measurements are presented of the t-channel single-top-quark production cross section in proton-proton collisions at ?s = 8 TeV. The results are based on a data sample corresponding to an integrated luminosity of 19.7 fb? recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop $ \\left(\\overline{\\mathrm{t}}\\right) $ , in final states with a muon or an electron. The measured inclusive t-channel cross section is ?t-ch. = 83.6 2.3 (stat.) 7.4 (syst.) pb. The single t and $ \\overline{\\mathrm{t}} $ cross sections are measured to be ?t-ch.(t) = 53.8 1.5 (stat.) 4.4 (syst.) pb and ?$_{t-ch.}$ $ \\left(\\overline{t}\\right) $ = 27.6 1.3 (stat.) 3.7 (syst.) pb, respectively. The measured ratio of cross sections is Rt-ch. = ?t-ch.(t)/?t-ch. $ \\left(\\overline{\\mathrm{t}}\\right) $ = 1.95 0.10 (stat.) 0.19 (syst.), in agreement with the standard model prediction. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vtb is extracted and, in combination with a previous CMS result at ?s = 7 TeV, a value |Vtb| = 0.998 0.038 (exp.) 0.016 (theo.) is obtained.

  20. Top Physics at the Tevatron Cecilia E. Gerber

    E-Print Network [OSTI]

    Gerber, Cecilia E.

    Top Physics at the Tevatron Cecilia E. Gerber University of Illinois-Chicago 2008 Linear Collider · Motivation Introduction to top production and decay· Introduction to top production and decay · Studies of Top quark pair production and decay properties ­ Is the SM correct? ­ Model-dependent searches

  1. Stop on Top: SUSY Parameter Regions, Fine-Tuning Constraints

    E-Print Network [OSTI]

    Demir, Durmus Ali

    2014-01-01T23:59:59.000Z

    We analyze common supersymmetric models in order to determine in what parameter regions with what amount of fine-tuning they are capable of accomodating the LHC-allowed top-stop degeneracy window. The stops must be light enough to enable Higgs naturalness yet heavy enough to induce a 125 GeV Higgs boson mass. These two constraints require the two stops to have a large mass splitting. We find that, compared to the usual neutralino-LSP CMSSM, the NUHM and gravitino-LSP CMSSM models possess relatively wide regions in which the light stop weighs close to the top quark. The fine-tuning involved lies in 10^3-10^4 range.

  2. Search for the Standard Model Higgs boson produced in association with top quarks and decaying into $b\\bar{b}$ in pp collisions at $\\sqrt{s}$ = 8 TeV with the ATLAS detector

    E-Print Network [OSTI]

    Aad, Georges; ATLAS Collaboration; Abdallah, Jalal; Abdinov, Ovsat; Aben, Rosemarie; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Abreu, Ricardo; Abulaiti, Yiming; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Adelman, Jahred; Adomeit, Stefanie; Adye, Tim; Affolder, Tony; Agatonovic-Jovin, Tatjana; Aguilar-Saavedra, Juan Antonio; Agustoni, Marco; Ahlen, Steven; Ahmadov, Faig; Aielli, Giulio; Akerstedt, Henrik; kesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Alberghi, Gian Luigi; Albert, Justin; Albrand, Solveig; Alconada Verzini, Maria Josefina; Aleksa, Martin; Aleksandrov, Igor; Alexa, Calin; Alexander, Gideon; Alexopoulos, Theodoros; Alhroob, Muhammad; Alimonti, Gianluca; Alio, Lion; Alison, John; Alkire, Steven Patrick; Allbrooke, Benedict; Allport, Phillip; Aloisio, Alberto; Alonso, Alejandro; Alonso, Francisco; Alpigiani, Cristiano; Altheimer, Andrew David; Alvarez Gonzalez, Barbara; ?lvarez Piqueras, Damin; Alviggi, Mariagrazia; Amako, Katsuya; Amaral Coutinho, Yara; Amelung, Christoph; Amidei, Dante; Amor Dos Santos, Susana Patricia; Amorim, Antonio; Amoroso, Simone; Amram, Nir; Amundsen, Glenn; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Angelidakis, Stylianos; Angelozzi, Ivan; Anger, Philipp; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoki, Masato; Aperio Bella, Ludovica; Arabidze, Giorgi; Arai, Yasuo; Araque, Juan Pedro; Arce, Ayana; Arduh, Francisco Anuar; Arguin, Jean-Francois; Argyropoulos, Spyridon; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arnold, Hannah; Arratia, Miguel; Arslan, Ozan; Artamonov, Andrei; Artoni, Giacomo; Asai, Shoji; Asbah, Nedaa; Ashkenazi, Adi; sman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astalos, Robert; Atkinson, Markus; Atlay, Naim Bora; Auerbach, Benjamin; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Axen, Bradley; Ayoub, Mohamad Kassem; Azuelos, Georges; Baak, Max; Baas, Alessandra; Bacci, Cesare; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagiacchi, Paolo; Bagnaia, Paolo; Bai, Yu; Bain, Travis; Baines, John; Baker, Oliver Keith; Balek, Petr; Balestri, Thomas; Balli, Fabrice; Banas, Elzbieta; Banerjee, Swagato; Bannoura, Arwa A E; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnes, Sarah Louise; Barnett, Bruce; Barnett, Michael; Barnovska, Zuzana; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimares da Costa, Joo; Bartoldus, Rainer; Barton, Adam Edward; Bartos, Pavol; Bassalat, Ahmed; Basye, Austin; Bates, Richard; Batista, Santiago Juan; Batley, Richard; Battaglia, Marco; Bauce, Matteo; Bauer, Florian; Bawa, Harinder Singh; Beacham, James Baker; Beattie, Michael David; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Maurice; Becker, Sebastian; Beckingham, Matthew; Becot, Cyril; Beddall, Andrew; Beddall, Ayda; Bednyakov, Vadim; Bee, Christopher; Beemster, Lars; Beermann, Thomas; Begel, Michael; Behr, Janna Katharina; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellerive, Alain; Bellomo, Massimiliano; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bender, Michael; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Bensinger, James; Bentvelsen, Stan; Beresford, Lydia; Beretta, Matteo; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Beringer, Jrg; Bernard, Clare; Bernard, Nathan Rogers; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Berta, Peter; Bertella, Claudia; Bertoli, Gabriele; Bertolucci, Federico; Bertsche, Carolyn; Bertsche, David; Besana, Maria Ilaria; Besjes, Geert-Jan; Bessidskaia Bylund, Olga; Bessner, Martin Florian; Besson, Nathalie; Betancourt, Christopher; Bethke, Siegfried; Bevan, Adrian John; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianchini, Louis; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Biglietti, Michela; Bilbao De Mendizabal, Javier; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet

    2015-01-01T23:59:59.000Z

    A search for the Standard Model Higgs boson produced in association with a pair of top quarks, $t\\bar{t}H$, is presented. The analysis uses 20.3 fb$^{-1}$ of pp collision data at $\\sqrt{s}$ = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H to $b\\bar{b}$ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by $t\\bar{t}$+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible $t\\bar{t}$+$b\\bar{b}$ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross sectio...

  3. Search for Scalar Bottom Quarks from Gluino Decays in Proton - Anti-proton Collisions at a Center-of-Mass Energy of 1.96-TeV

    SciTech Connect (OSTI)

    Rott, Carsten (ORCID:0000000269586033)

    2004-12-01T23:59:59.000Z

    The authors have performed a search for the scalar bottom quark ({tilde b}{sub 1}) from gluino ({tilde g}) decays in an R-parity conserving SUSY scenario with m{sub {tilde g}} > m{sub {tilde b}{sub 1}}, by investigating a final state of large missing transverse energy, with three or more jets, and some of them from the hadronization of b-quarks. A data sample of 156 pb{sup -1} collected by the Collider Detector at Fermilab at a center-of-mass energy of {radical}s = 1.96 TeV was used. For the final selection, jets containing secondary displaced vertices were required. This analysis has been performed ''blind'', in that the inspection of the signal region was only made after the Standard Model prediction was finalized. Comparing data with SUSY predictions, they can exclude masses of the gluino and sbottom of up to 280 and 240 GeV/c{sup 2} respectively.

  4. Constraints on the Mass and Mixing of the 4th Generation Quark From Direct CP Violation$?^{\\prime}/?$ and Rare K Decays

    E-Print Network [OSTI]

    Chao-Shang Huang; Wu-Jun Huo; Yue-Liang Wu

    2000-08-04T23:59:59.000Z

    We investigate the $\\epsilon^{\\prime} /\\epsilon$ for $K\\to \\pi\\pi$ in a sequential fourth generation model. By giving the basic formulae for $\\epsilon^{\\prime}/\\epsilon$ in this model, we analyze the numerical results which are dependent of $m_{t^{\\prime}}$ and imaginary part of the fourth CKM factor, ${Im}V^{*}_{t^{'}s}V_{t^{'}d}$ (or $V^{*}_{t^{'}s}V_{t^{'}d}$ and the fourth generation CKM matrix phase $\\theta$). We find that, unlike the SM, when taking the central values of all parameters for $\\epsilon^{\\prime}/\\epsilon$, the values of $\\epsilon^{\\prime}/ \\epsilon$ can easily fit to the current experimental data for all values of hadronic matrix elements estimated from various approaches. Also, we show that the experimental values of $\\epsilon^{\\prime}/\\epsilon$ and rare K decays can provide a strong constraint on both mass and mixing of the fourth generation quark. When taking the values of hadronic matrix elements from the lattice or 1/N expansion calculations, a large region of the up-type quark mass $m_{t^{\\prime}}$ is excluded.

  5. Top physics at CDF

    SciTech Connect (OSTI)

    Hughes, R.E. [Univ. of Rochester, NY (United States)

    1997-01-01T23:59:59.000Z

    We report on top physics results using a 100 pb{sup -1} data sample of p{bar p} collisions at {radical}s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). We have identified top signals in a variety of decay channels, and used these channels to extract a measurement of the top mass and production cross section. A subset of the data (67 pb{sup -1}) is used to determine M{sub top} = 176 {+-} 8(stat) {+-} 10(syst) and {sigma}(tt) = 7.6 {sub -2.0}{sup +2.4} pb. We present studies of the kinematics of t{bar t} events and extract the first direct measurement of V{sub tb}. Finally, we indicate prospects for future study of top physics at the Tevatron.

  6. Single Top Production at the Tevatron

    SciTech Connect (OSTI)

    Wu, Zhenbin; /Baylor U.

    2012-05-01T23:59:59.000Z

    We present recent results of single top quark production in the lepton plus jet final state, performed by the CDF and D0 collaborations based on 7.5 and 5.4 fb{sup -1} of p{bar p} collision data collected at {radical}s = 1.96 TeV from the Fermilab Tevatron collider. Multivariate techniques are used to separate the single top signal from the backgrounds. Both collaborations present measurements of the single top quark cross section and the CKM matrix element |V{sub tb}|. A search for anomalous Wtb coupling from D0 is also presented.

  7. Search for pair production of third-generation scalar leptoquarks and top squarks in protonproton collisions at ?s = 8 TeV

    E-Print Network [OSTI]

    CMS Collaboration

    A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a ...

  8. Singlet Free Energies of a Static Quark-Antiquark Pair

    E-Print Network [OSTI]

    Konstantin Petrov

    2004-09-01T23:59:59.000Z

    We study the singlet part of the free energy of a static quark anti-quark pair at finite temperature in three flavor QCD with degenerate quark masses using $N_{\\tau}=4$ and 6 lattices with Asqtad staggered fermion action. We look at thermodynamics of the system around phase transition and study its scaling with lattice spacing and quark masses.

  9. Search for Pair Production of Heavy Top-Like Quarks Decaying to a High-p[subscript T]W Boson and a b Quark in the Lepton Plus Jets Final State at ?s = 7 TeV with the ATLAS Detector

    E-Print Network [OSTI]

    Taylor, Frank E.

    A search is presented for production of a heavy up-type quark (t[superscript ?]) together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is ...

  10. Press Pass - Press Release - Single top quark

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible forPortsmouth/Paducah ProjectPRE-AWARDenergy useNational Security0 April420

  11. Press Pass - Press Release - Single top quark

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible forPortsmouth/Paducah ProjectPRE-AWARDenergy useNational Security0 April4209-04 March 9,

  12. Fermilab - Top Quark Press Release (Historical)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC) Environmental Assessments (EA)Budget » FYU.S. DOEFigure 1. CMDJulyThe

  13. Search for a Vectorlike Quark with Charge 2/3 in t+Z Events from pp Collisions at ?s=7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Er, J.; Fabjan, C.; Friedl, M.; et al

    2011-12-01T23:59:59.000Z

    A search for pair-produced heavy vectorlike charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 fb?, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for themoredecay T?tZ, a T quark with a mass less than 475 GeV/c is excluded at the 95% confidence level.less

  14. Search for a Vectorlike Quark with Charge 2/3 in t+Z Events from pp Collisions at ?s=7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Er, J.; Fabjan, C.; Friedl, M.; Frhwirth, R.; Ghete, V. M.; Hammer, J.; Hnsel, S.; Hoch, M.; Hrmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, H.; Schfbeck, R.; Strauss, J.; Taurok, A.; Teischinger, F.; Trauner, C.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Benucci, L.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Maes, T.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Blekman, F.; Blyweert, S.; DHondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Charaf, O.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hammad, G. H.; Hreus, T.; Marage, P. E.; Raval, A.; Thomas, L.; Vander Marcken, G.; Vander Velde, C.; Vanlaer, P.; Adler, V.; Cimmino, A.; Costantini, S.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ryckbosch, D.; Thyssen, F.; Tytgat, M.; Vanelderen, L.; Verwilligen, P.; Walsh, S.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Caudron, J.; Ceard, L.; Cortina Gil, E.; De Favereau De Jeneret, J.; Delaere, C.; Favart, D.; Giammanco, A.; Grgoire, G.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Ovyn, S.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Beliy, N.; Caebergs, T.; Daubie, E.; Alves, G. A.; Brito, L.; De Jesus Damiao, D.; Pol, M. E.; Souza, M. H. G.; Ald Jnior, W. L.; Carvalho, W.; Da Costa, E. M.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Silva Do Amaral, S. M.; Sznajder, A.; Anjos, T. S.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Darmenov, N.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Karadzhinova, A.; Kozhuharov, V.; Litov, L.; Mateev, M.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Ban, Y.; Guo, S.; Guo, Y.; Li, W.; Mao, Y.; Qian, S. J.; Teng, H.; Zhu, B.; Zou, W.; Cabrera, A.; Gomez Moreno, B.; Ocampo Rios, A. A.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Lelas, K.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Dzelalija, M.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Hektor, A.; Kadastik, M.; Mntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Azzolini, V.; Eerola, P.; Fedi, G.; Voutilainen, M.; Czellar, S.; Hrknen, J.; Heikkinen, A.; Karimki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampn, T.; Lassila-Perini, K.; Lehti, S.; Lindn, T.; Luukka, P.; Menp, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Karjalainen, A.; Korpela, A.; Tuuva, T.; Sillou, D.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Marionneau, M.; Millischer, L.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Dahms, T.; Dobrzynski, L.; Elgammal, S.; Granier de Cassagnac, R.; Haguenauer, M.; Min, P.; Mironov, C.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Thiebaux, C.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Ferro, C.; Fontaine, J.-C.; Gel, D.; Goerlach, U.; Greder, S.; Juillot, P.; Karim, M.; Le Bihan, A.-C.; Mikami, Y.; Van Hove, P.; Fassi, F.; Mercier, D.; Baty, C.; Beauceron, S.; Beaupere, N.; Bedjidian, M.; Bondu, O.; Boudoul, G.; Boumediene, D.; Brun, H.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Ille, B.; Kurca, T.; Le Grand, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sordini, V.; Tosi, S.; Tschudi, Y.; Verdier, P.; Viret, S.; Lomidze, D.; Anagnostou, G.; Beranek, S.; Edelhoff, M.; Feld, L.; Heracleous, N.; Hindrichs, O.; Jussen, R.; Klein, K.; Merz, J.

    2011-12-01T23:59:59.000Z

    A search for pair-produced heavy vectorlike charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 fb?, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for the decay T?tZ, a T quark with a mass less than 475 GeV/c is excluded at the 95% confidence level.

  15. Search for a Vectorlike Quark with Charge 2/3 in t+Z Events from pp Collisions at sqrt[s]=7??TeV

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; et al.

    2011-12-01T23:59:59.000Z

    A search for pair-produced heavy vector-like charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 inverse femtobarns, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for the decay T to tZ, a T quark with a mass less than 475 GeV/c^2 is excluded at the 95% confidence level.

  16. On quark-lepton complementarity

    E-Print Network [OSTI]

    F. Gonzalez-Canales; A. Mondragon

    2006-06-16T23:59:59.000Z

    Recent measurements of the neutrino solar mixing angle and the Cabibbo angle satisfy the empirical relation theta_{sol} + theta_{C} ~ 45^{o}. This relation suggests the existence of a correlation between the mixing matrices of leptons and quarks, the so called quark-lepton complementarity. Here, we examine the possibility that this correlation originates in the strong hierarchy in the mass spectra of quarks and charged leptons, and the seesaw mechanism that gives mass to the Majorana neutrinos. In a unified treatment of quarks and leptons in which the mass matrices of all fermions have a similar Fritzsch texture, we calculate the mixing matrices V_{CKM} and U_{MNSP} as functions of quark and lepton masses and only two free parameters, in very good agreement with the latest experimental values on masses and mixings. Three essential ingredients to explain the quark-lepton complementarity relation are identified: the strong hierarchy in the mass spectra of quarks and charged leptons, the normal seesaw mechanism and the assumption of maximal CP violation in the lepton sector.

  17. On quark-lepton complementarity

    SciTech Connect (OSTI)

    Gonzalez Canales, F.; Mondragon, A. [Instituto de Fisica, UNAM, 04510, Mexico D.F. (Mexico)

    2006-09-25T23:59:59.000Z

    Recent measurements of the neutrino solar mixing angle and the Cabibbo angle satisfy the empirical relation {theta}{sub sol} + {theta}{sub C} {approx_equal} ({pi}/4). This relation suggests the existence of a correlation between the mixing matrices of leptons and quarks, the so called quark-lepton complementarity. Here, we examine the possibility that this correlation originates in the strong hierarchy in the mass spectra of quarks and charged leptons, and the seesaw mechanism that gives mass to the Majorana neutrinos. In a unified treatment of quarks and leptons in which the mass matrices of all fermions have a similar Fritzsch texture, we calculate the mixing matrices VCKM and UMNSP as functions of quark and lepton masses and only two free parameters, in very good agreement with the latest experimental values on masses and mixings. Three essential ingredients to explain the quark-lepton complementarity relation are identified: the strong hierarchy in the mass spectra of quarks and charged leptons, the normal seesaw mechanism and the assumption of maximal CP violation in the lepton sector.

  18. Two-dimensional liquid chromatography system for online top-down...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    liquid chromatography system for online top-down mass spectrometry. Two-dimensional liquid chromatography system for online top-down mass spectrometry. Abstract: An online...

  19. Exotic hybrid mesons with light quarks

    E-Print Network [OSTI]

    Claude Bernard; Tom Blum; Thomas A. DeGrand; Carleton DeTar; Steven Gottlieb; Urs. M. Heller; Jim Hetrick; Craig McNeile; Kari Rummukainen; Bob Sugar; Doug Toussaint; Matt Wingate

    1996-07-12T23:59:59.000Z

    Hybrid mesons, made from a quark, an antiquark and gluons, can have quantum numbers inaccessible to conventional quark-antiquark states. Confirmation of such states would give information on the role of "dynamical" color in low energy QCD. We present preliminary results for hybrid meson masses using light Wilson valence quarks.

  20. Search for Top Squark and Higgsino Production Using Diphoton Higgs Boson Decays

    E-Print Network [OSTI]

    Apyan, Aram

    Results are presented of a search for a natural supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top quark (the top squark) and the Higgs boson ...