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Sample records for top quark mass

  1. Top quark mass measurements at CDF

    SciTech Connect (OSTI)

    Brubaker, Erik; /Chicago U., EFI

    2006-05-01

    The mass of the top quark M{sub top} is interesting both as a fundamental parameter of the standard model and as an important input to precision electroweak tests. The Collider Detector at Fermilab (CDF) has a robust program of top quark mass analyses, including the most precise single measurement, M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}, using 680 pb{sup -1} of p{bar p} collision data. A combination of current results from CDF gives M{sub top} = 172.0 {+-} 2.7 GeV/c{sup 2}, surpassing the stated goal of 3 GeV/c{sup 2} precision using 2 fb{sup -1} of data. Finally, a combination with current D0 results gives a world average top quark mass of 172.5 {+-} 2.3 GeV/c{sup 2}.

  2. Precision Determination of the Top Quark Mass

    SciTech Connect (OSTI)

    Movilla Fernandez, Pedro A.; /LBL, Berkeley

    2007-05-01

    The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at {radical}s = 1.96 TeV produced at the Tevatron. The uncertainties in each of the top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1 fb{sup -1} of data per experiment is 170.9 {+-} 1.8 GeV/c{sup 2}.

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

    SciTech Connect (OSTI)

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

    2011-06-03

    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.

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

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

    Aaltonen, T

    2011-06-03

    We present a measurement of the top quark mass in the lepton+jets and dilepton channels of tmore » $$\\bar{t}$$ decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb-1 of p$$\\bar{p}$$ 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 = 172.1±1.1 (stat)±0.9 (syst) GeV/c2.« less

  5. Precision Top-Quark Mass Measurements at CDF

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-07-01

    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}.

  6. Unified spin gauge model and the top quark mass

    SciTech Connect (OSTI)

    Chisholm, J.S.R.; Farwell, R.S.

    1995-10-01

    Spin gauge models use a real Clifford algebraic structure R{sub p,q} associated with a real manifold of dimension p + q to describe the fundamental interactions of elementary particles. This review provides a comparison between those models and the standard model, indicating their similarities and differences. By contrast with the standard model, the spin gauge model based on R{sub 3,8} generates intermediate boson mass terms without the need to use the Higgs-Kibble mechanism and produces a precise prediction for the mass of the top quark. The potential of this model to account for exactly three families of fermions is considered.

  7. Top quark mass measurement from dilepton events at CDF II

    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, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara /Cantabria Inst. of Phys.

    2005-12-01

    We report a measurement of the top quark mass using events collected by the CDF II Detector from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top mass in events that are consistent with t{bar t} {yields} {bar b}{ell}{sup -}{bar {nu}}{sub {ell}}b{ell}{prime}{sup +}{nu}{sub {ell}}{prime} decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb{sup -1} of integrated luminosity, yielding a top quark mass M{sub t} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This first application of a matrix-element technique to t{bar t} {yields} b{ell}{sup +}{nu}{sub {ell}}{bar b}{ell}{prime}{sup -}{bar {nu}}{sub {ell}}, decays gives the most precise single measurement of M{sub t} in dilepton events. Combined with other CDF Run II measurements using dilepton events, we measure M{sub t} = 167.9 {+-} 5.2(stat.) {+-} 3.7(syst.) GeV/c{sup 2}.

  8. Precision measurement of the top quark mass in the lepton + jets channel

    Office of Scientific and Technical Information (OSTI)

    using a matrix element method with Quasi-Monte Carlo integration (Thesis/Dissertation) | SciTech Connect Thesis/Dissertation: Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with Quasi-Monte Carlo integration Citation Details In-Document Search Title: Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with Quasi-Monte Carlo integration This thesis presents a measurement of the top quark

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

    SciTech Connect (OSTI)

    Fedorko, Wojciech T.; /Chicago U.

    2008-09-01

    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.

  10. 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

    2013-07-01

    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.

  11. 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.

    2013-07-01

    We present a measurement of the top-quark mass with tt̄ events using a data sample corresponding to an integrated luminosity of 5.7 fb -1 of pp̄ 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 tt̄ decay channel, including events that contain tau leptons, which are usually not included inmore » 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.« less

  12. 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

    2011-08-09

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; → tt̄ 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 Γ + 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, wemore »measure a top-quark mass of mt = 174.94 ± 1.49 GeV for a total integrated luminosity of 3.6 fb-1.« less

  13. 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

    2011-08-09

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; → tt̄ 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 Γ + 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, wemore » measure a top-quark mass of mt = 174.94 ± 1.49 GeV for a total integrated luminosity of 3.6 fb-1.« less

  14. Measurement of the top quark mass in lepton+jets events with secondary vertex tagging

    SciTech Connect (OSTI)

    Harrington, Robert Duane; /Northeastern U.

    2007-02-01

    A measurement of the top quark mass with the matrix element method in the lepton + jets final state in D0 Run II is presented. Events with single isolated energetic charged lepton (electron or muon), exactly four calorimeter jets, and significant missing transverse energy are selected. Probabilities used to discriminate between signal and background are assumed to be proportional to differential cross-sections, calculated using event kinematics and folding in object resolutions and parton distribution functions. The event likelihoods constructed using these probabilities are varied with the top quark mass, m{sub t}, and the jet energy scale, JES, to give the smallest possible combined statistical + JES uncertainty.

  15. Measurement of cross section of quark pair production top with the D0 experiment at the Tevatron and determination the top quark mass using this measure

    SciTech Connect (OSTI)

    Chevalier-Thery, Solene; /Paris U., VI-VII /Saclay

    2010-06-01

    The top quark has been discovered by CDF and D0 experiments in 1995 at the proton-antiproton collider Tevatron. The amount of data recorded by both experiments makes it possible to accurately study the properties of this quark: its mass is now known to better than 1% accuracy. This thesis describes the measurement of the top pair cross section in the electron muon channel with 4, 3 fb{sup -1} recorded data between 2006 and 2009 by the D0 experiment. Since the final state included a muon, improvements of some aspects of its identification have been performed : a study of the contamination of the cosmic muons and a study of the quality of the muon tracks. The cross section measurement is in good agreement with the theoretical calculations and the other experimental measurements. This measurement has been used to extract a value for the top quark mass. This method allows for the extraction of a better defined top mass than direct measurements as it depends less on Monte Carlo simulations. The uncertainty on this extracted mass, dominated by the experimental one, is however larger than for direct measurements. In order to decrease this uncertainty, the ratio of the Z boson and the top pair production cross sections has been studied to look for some possible theoretical correlations. At the Tevatron, the two cross sections are not theoretically correlated: no decrease of the uncertainty on the extracted top mass is therefore possible.

  16. Measurement of the Top Quark Mass in the All-Hadronic Mode at CDF

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2011-12-01

    A measurement of the top quark mass (M{sub top}) in the all-hadronic decay channel is presented. It uses 5.8 fb{sup -1} of p{bar p} data collected with the CDF II detector at the Fermilab Tevatron Collider. Events with six to eight jets are selected by a neural network algorithm and by the requirement that at least one of the jets is tagged as a b quark jet. The measurement is performed with a likelihood fit technique, which simultaneously determines M{sub top} and the jet energy scale (JES) calibration. The fit yields a value of M{sub top} = 172.5 {+-} 1.4 (stat) {+-} 1.0 (JES) {+-} 1.1 (syst) GeV/c{sup 2}.

  17. Precision measurement of the top-quark mass in lepton$+$jets final states

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

    Abazov, Victor Mukhamedovich

    2015-06-04

    We measure the mass of the top quark in lepton þ jets final states using the full sample of pp¯ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at √s = 1.96 TeV, corresponding to 9.7 fb-1 of integrated luminosity. We also use a matrix element technique that calculates the probabilities for each event to result from tt¯ production or background. Furthermore, the overall jet energy scale is constrained in situ by the mass of the W boson. We measure mt = 174.98 ± 0.76 GeV. As a result, this constitutes the mostmore » precise single measurement of the top-quark mass.« less

  18. Precision measurement of the top-quark mass in lepton+jets final states

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

    Abazov, Victor Mukhamedovich

    2014-07-17

    We measure the mass of the top quark in leptonmore » $+$jets final states using the full sample of $$p\\bar{p}$$ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at $$\\sqrt s=1.96 $$TeV, corresponding to $$9.7 {\\rm fb}^{-1}$$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $$t\\bar t$$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $$m_t=174.98\\pm0.76$$ GeV. In conclusion, this constitutes the most precise single measurement of the top-quark mass.« less

  19. Precision measurement of the top-quark mass in lepton+jets final states

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

    Abazov, Victor Mukhamedovich

    2014-07-17

    We measure the mass of the top quark in lepton$+$jets final states using the full sample of $p\\bar{p}$ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at $\\sqrt s=1.96 $TeV, corresponding to $9.7 {\\rm fb}^{-1}$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $t\\bar t$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $m_t=174.98\\pm0.76$ GeV. In conclusion, this constitutes the most precise single measurement of the top-quark mass.

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

    Office of Scientific and Technical Information (OSTI)

    Discoveries at Fermilab - The Top Quark, February 2001 The Top Quark: Worth its Weight in Gold, 2003 New Precision Measurement of Top Quark Mass, June 2004 Properties of the Top ...

  1. A Measurement of the Mass of the Top Quark in Lepton + Jets Events at CDF

    SciTech Connect (OSTI)

    Brubaker, Erik Matthews

    2004-12-01

    This document presents a measurement of the top quark mass using the CDF run II detector at Fermilab. Colliding beams of protons and anti-protons at Fermilab's Tevatron ({radical}s = 1.96 TeV) produce top/anti-top pairs, which decay to W{sup +}W{sup -} b{bar b}; events are selected where one W decays hadronically, and one W decays to either e or {mu} plus a neutrino. The data sample was collected between March 2002 and September 2003, and corresponds to an integrated luminosity of approximately 162 pb{sup -1}. Thirty-seven candidate t{bar t} events are found with at least one b jet identified by its displaced vertex. In each event, the best fit top quark invariant mass is determined by minimizing a {chi}{sup 2} for the overconstrained kinematic system. A likelihood fit of the reconstructed masses in the data sample to distributions from simulated signal and background events gives a top mass of 174.9{sub -7.7}{sup +7.1}(stat.) {+-} 6.5(syst.) GeV/c{sup 2}. The dominant systematic error is due to uncertainties in the jet energy measurements.

  2. Precise measurement of the top quark mass in dilepton decays using optimized neutrino weighting

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

    Abazov, Victor Mukhamedovich

    2015-11-11

    We measure the top quark mass in dilepton final states of tt¯ events in pp¯ collisions at √s= 1.96 TeV, using data corresponding to an integrated luminosity of 9.7 fb-1 at the Fermilab Tevatron Collider. The analysis features a comprehensive optimization of the neutrino weighting method to minimize the statistical uncertainties. Furthermore, we improve the calibration of jet energies using the calibration determined in tt¯ → lepton + jets events, which reduces the otherwise limiting systematic uncertainty from the jet energy scale. As a result, the measured top quark mass is mt = 173.32±1.36(stat)±0.85(syst) GeV.

  3. Top quark mass measurement from dilepton events at CDF II with the matrix-element method

    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. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2006-05-01

    We describe a measurement of the top quark mass using events with two charged leptons collected by the CDF II detector from p{bar p} collisions with {radical}s = 1.96 TeV at the Fermilab Tevatron. The likelihood in top mass is calculated for each event by convoluting the leading order matrix element describing q{bar q} {yields} t{bar t} {yields} b{ell}{nu}{sub {ell}}{bar b}{ell}{prime} {nu}{sub {ell}}, with detector resolution functions. The presence of background events in the data sample is modeled using similar calculations involving the matrix elements for major background processes. In a data sample with integrated luminosity of 340 pb{sup -1}, we observe 33 candidate events and measure M{sub top} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This measurement represents the first application of this method to events with two charged leptons and is the most precise single measurement of the top quark mass in this channel.

  4. Precision measurement of the top quark mass from dilepton events at CDF II

    SciTech Connect (OSTI)

    Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2006-12-01

    We report a measurement of the top quark mass, M{sub t}, in the dilepton decay channel of t{bar t} {yields} b{ell}{prime}{sup +} {nu}{sub {ell}}, {bar b}{ell}{sup -}{bar {nu}}{sub {ell}} using an integrated luminosity of 1.0 fb{sup -1} of p{bar p} collisions collected with the CDF II detector. We apply a method that convolutes a leading-order matrix element with detector resolution functions to form event-by-event likelihoods; we have enhanced the leading-order description to describe the effects of initial-state radiation. The joint likelihood is the product of the likelihoods from 78 candidate events in this sample, which yields a measurement of M{sub t} = 164.5 {+-} 3.9(stat.) {+-} 3.9(syst.) GeV/c{sup 2}, the most precise measurement of M{sub t} in the dilepton channel.

  5. Observation of the Top Quark

    DOE R&D Accomplishments [OSTI]

    Kim, S. B.

    1995-08-01

    Top quark production is observed in{bar p}p collisions at{radical}s= 1.8 TeV at the Fermilab Tevatron. The Collider Detector at Fermilab (CDF) and D{O} observe signals consistent with t{bar t} to WWb{bar b}, but inconsistent with the background prediction by 4.8{sigma} (CDF), 4.6a (D{O}). Additional evidence for the top quark Is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top quark decay. They measure the top quark mass to be 176{plus_minus}8(stat.){plus_minus}10(sys.) GeV/c{sup 2} (CDF), 199{sub -21}{sup+19}(stat.){plus_minus}22(sys.) GeV/c{sup 2} (D{O}), and the t{bar t} production cross section to be 6.8{sub -2.4}{sup+3.6}pb (CDF), 6.4{plus_minus}2.2 pb (D{O}).

  6. Measurement of the Top Quark Mass Using the Invariant Mass of Lepton Pairs in Soft Muon b-tagged Events

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E.; Anastassov, A.; Annovi, Alberto; Antos, Jaroslav; Apollinari, G.; Apresyan, A.; /Purdue U. /Waseda U.

    2009-06-01

    We present the first measurement of the mass of the top quark in a sample of t{bar t} {yields} {ell}{bar {nu}}b{bar b}q{bar q} events (where {ell} = e, {mu}) selected by identifying jets containing a muon candidate from the semileptonic decay of heavy-flavor hadrons (soft muon b-tagging). The p{bar p} collision data used corresponds to an integrated luminosity of 2 fb{sup -1} and was collected by the CDF II detector at the Fermilab Tevatron. The measurement is based on a novel technique exploiting the invariant mass of a subset of the decay particles, specifically the lepton from the W boson of the t {yields} Wb decay, and the muon from a semileptonic b decay. We fit template histograms, derived from simulation of t{bar t} events and a modeling of the background, to the mass distribution observed in the data and measure a top quark mass of 180.5 {+-} 12.0(stat.) {+-} 3.6(syst.) GeV/c{sup 2}, consistent with the current world average.

  7. Quark Masses

    SciTech Connect (OSTI)

    Gasser, Juerg

    2005-10-26

    In my talk, I reviewed some basic aspects of quark masses: what do they mean, how can they be determined, what is our present knowledge on them. The talk was addressed to non specialists in the field, and so is this write up.

  8. Precision measurement of the top quark mass in the lepton + jets...

    Office of Scientific and Technical Information (OSTI)

    integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects. We calculate a tbar t likelihood as a 2-D...

  9. Measurement of the top quark mass using the template method in the lepton plus jets channel with in situ W ---> j j calibration at CDF-II

    SciTech Connect (OSTI)

    Adelman, Jahred A.; Arguin, J.F.; Bellettini, G.; Brubaker, E.; Budagov, J.; Chlachidze, G.; Demortier, L.; Gibson, A.; Kim, S.; Kim, Y.K.; Maruyama, T.; Sato, K.; Shochet, M.; Sinervo, P.; Tomura, T.; Velev, G.; Xie, S.; Yang, U.K.; /Chicago U. /Toronto U. /INFN, Pisa /Dubna, JINR /Rockefeller U. /LBL, Berkeley /Tsukuba U. /Fermilab

    2006-05-01

    We report an updated measurement of the top quark mass in the lepton plus jets channel of t{bar t} events from p{bar p} collisions at {radical}s = 1.96 TeV. This measurement uses a dataset with integrated luminosity of 680 pb{sup -1}, containing 360 t{bar t} candidates separated into four subsamples. A top quark mass is reconstructed for each event by using energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of hadronic W boson decays W {yields} jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement: the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the true top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain: M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}.

  10. Measurement of the top-quark mass in the tt dilepton channel using the full CDF Run II data set

    SciTech Connect (OSTI)

    Aaltonen, T.

    2015-08-06

    We present a measurement of the top-quark mass in events containing two leptons (electrons or muons) with a large transverse momentum, two or more energetic jets, and a transverse-momentum imbalance. We use the full proton-antiproton collision data set collected by the CDF experiment during the Fermilab Tevatron Run II at center-of-mass energy ?s = 1.96 TeV, corresponding to an integrated luminosity of 9.1 fb1. A special observable is exploited for an optimal reduction of the dominant systematic uncertainty, associated with the knowledge of the absolute energy of the hadronic jets. The distribution of this observable in the selected events is compared to simulated distributions of tt dilepton signal and background. We measure a value for the top-quark mass of 171.51.9 (stat)2.5 (syst) GeV/c2.

  11. The Top Quark, QCD, And New Physics.

    DOE R&D Accomplishments [OSTI]

    Dawson, S.

    2002-06-01

    The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup+}e{sup -}+ t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup+}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

  12. Measurement of the Top Quark Mass in the Lepton+Jets Channel Using the Lepton Transverse Momentum

    SciTech Connect (OSTI)

    Aaltonen, T.; Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; /Purdue U. /Waseda U. /Dubna, JINR

    2011-01-01

    This letter reports a measurement of the top quark mass, M{sub top}, in data from p{bar p} collisions at {radical}s = 1.96 TeV corresponding to 2.7 fb{sup -1} of integrated luminosity at the Fermilab Tevatron using the CDF II detector. Events with the lepton+jets topology are selected. An unbinned likelihood is constructed based on the dependence of the lepton transverse momentum, P{sub T}, on M{sub top}. A maximum likelihood fit to the data yields a measured mass M{sub top} = 176.9 {+-} 8.0{sub stat} {+-} 2.7{sub syst} GeV/c{sup 2}. In this measurement, the contribution by the jet energy scale uncertainty to the systematic error is negligible. The result provides an important consistency test for other M{sub top} measurements where explicit use of the jet energy is made for deriving the top quark mass.

  13. Measurements of Top Quark Properties

    SciTech Connect (OSTI)

    Cerrito, Lucio

    2009-05-01

    Preliminary results on the measurement of four selected properties of the top quark are presented. The relative fraction of t{bar t} production through gluon fusion has been measured in the t{bar t} dilepton decay channel by the CDF Collaboration as F{sub gg} = 0.53{sub -0.38}{sup +0.36}. Using an integrated luminosity of 2.7 fb{sup -1} collected with the CDF II detector, we also determine the t{bar t} differential cross section with respect to values up to {approx}1 TeV of the t{bar t} invariant mass. We present a model-independent measurement of the helicity of W bosons produced in top quark decays, using an integrated luminosity of up to 2.7 fb{sup -1} collected by the D0 detector, and find the fraction of longitudinal W bosons f{sub 0} = 0.49 {+-} 0.14, and the fraction of right-handed W bosons f{sub +} = 0.11 {+-} 0.08. Finally, we measure the parton level forward-backward asymmetry of pair produced top quarks using an integrated luminosity of 3.2 fb{sup -1} collected with the CDF II detector, and find A{sub FB} = 0.19 {+-} 0.07. All results are consistent with the predictions of the standard model.

  14. Measurement of top quark polarisation in t-channel single top quark production

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-09

    Our first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb-1. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. Furthermore, a differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 0.03 (stat) 0.10 (syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.

  15. Measurement of the top-quark mass in the fully hadronic decay channel from ATLAS data at √s=7 TeV

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

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

    2015-04-23

    In this study, the mass of the top quark is measured in a data set corresponding to 4.6 fb-1 of proton–proton collisions with centre-of-mass energy √s=7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top–antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jetmore » to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt=175.1±1.4(stat.) ±1.2(syst.) GeV.« less

  16. Status of the top quark: Top production cross section and top properties

    SciTech Connect (OSTI)

    Boisvert, V.; /Rochester U.

    2006-08-01

    This report describes the latest cross section and property measurements associated with the top quark at the Tevatron Run II. The largest data sample used is 760 pb{sup -1} of integrated luminosity. Due to its large mass, the top quark might be involved in the process of electroweak symmetry breaking, making it a useful probe for signs of new physics.

  17. Determination of the top-quark pole mass using tt¯ + 1-jet events collected with the ATLAS experiment in 7TeV pp collisions

    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

    2015-10-19

    In this study, the normalized differential cross section for top-quark pair production in association with at least one jet is studied as a function of the inverse of the invariant mass of the tt¯ + 1-jet system. This distribution can be used for a precise determination of the top-quark mass since gluon radiation depends on the mass of the quarks. The experimental analysis is based on proton-proton collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.6 fb–1 . The selected events were identified using themore » lepton+jets top-quark-pair decay channel, where lepton refers to either an electron or a muon. The observed distribution is compared to a theoretical prediction at next-to-leading-order accuracy in quantum chromodynamics using the pole-mass scheme. With this method, the measured value of the top-quark pole mass, mpolet , is: mpolet = 173.7 ± 1.5(stat.) ± 1.4(syst.)+1.0–0.5(theory) GeV.« less

  18. Determination of the top-quark pole mass using tt + 1-jet events collected with the ATLAS experiment in 7TeV pp collisions

    SciTech Connect (OSTI)

    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.; 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.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Balek, P.; Balestri, T.; Balli, F.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Bansil, H. S.; Barak, L.; 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.; Bassalat, A.; Basye, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, 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.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. 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.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; 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.; 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.; Blanco, J. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Bogaerts, J. A.; Bogdanchikov, A. G.; 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.; 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.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Brown, J.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Bruschi, M.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Buehrer, F.; Bugge, L.; Bugge, M. K.; Bulekov, O.

    2015-10-19

    In this study, the normalized differential cross section for top-quark pair production in association with at least one jet is studied as a function of the inverse of the invariant mass of the tt + 1-jet system. This distribution can be used for a precise determination of the top-quark mass since gluon radiation depends on the mass of the quarks. The experimental analysis is based on proton-proton collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.6 fb1 . The selected events were identified using the lepton+jets top-quark-pair decay channel, where lepton refers to either an electron or a muon. The observed distribution is compared to a theoretical prediction at next-to-leading-order accuracy in quantum chromodynamics using the pole-mass scheme. With this method, the measured value of the top-quark pole mass, mpolet , is: mpolet = 173.7 1.5(stat.) 1.4(syst.)+1.00.5(theory) GeV.

  19. The Discovery of the Top Quark

    DOE R&D Accomplishments [OSTI]

    Sinervo, P.K.

    1995-12-01

    The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.

  20. Measurement of the top quark pair production cross section in proton-antiproton collisions at a center of mass energy of 1.96 TeV, hadronic top decays with the D0 detector

    SciTech Connect (OSTI)

    Hegeman, Jeroen Guido; /Twente U. Tech., Enschede

    2009-01-16

    Of the six quarks in the standard model the top quark is by far the heaviest: 35 times more massive than its partner the bottom quark and more than 130 times heavier than the average of the other five quarks. Its correspondingly small decay width means it tends to decay before forming a bound state. Of all quarks, therefore, the top is the least affected by quark confinement, behaving almost as a free quark. Its large mass also makes the top quark a key player in the realm of the postulated Higgs boson, whose coupling strengths to particles are proportional to their masses. Precision measurements of particle masses for e.g. the top quark and the W boson can hereby provide indirect constraints on the Higgs boson mass. Since in the standard model top quarks couple almost exclusively to bottom quarks (t {yields} Wb), top quark decays provide a window on the standard model through the direct measurement of the Cabibbo-Kobayashi-Maskawa quark mixing matrix element V{sub tb}. In the same way any lack of top quark decays into W bosons could imply the existence of decay channels beyond the standard model, for example charged Higgs bosons as expected in two-doublet Higgs models: t {yields} H{sup +}b. Within the standard model top quark decays can be classified by the (lepton or quark) W boson decay products. Depending on the decay of each of the W bosons, t{bar t} pair decays can involve either no leptons at all, or one or two isolated leptons from direct W {yields} e{bar {nu}}{sub e} and W {yields} {mu}{bar {nu}}{sub {mu}} decays. Cascade decays like b {yields} Wc {yields} e{bar {nu}}{sub e}c can lead to additional non-isolated leptons. The fully hadronic decay channel, in which both Ws decay into a quark-antiquark pair, has the largest branching fraction of all t{bar t} decay channels and is the only kinematically complete (i.e. neutrino-less) channel. It lacks, however, the clear isolated lepton signature and is therefore hard to distinguish from the multi-jet QCD background. It is important to measure the cross section (or branching fraction) in each channel independently to fully verify the standard model. Top quark pair production proceeds through the strong interaction, placing the scene for top quark physics at hadron colliders. This adds an additional challenge: the huge background from multi-jet QCD processes. At the Tevatron, for example, t{bar t} production is completely hidden in light q{bar q} pair production. The light (i.e. not bottom or top) quark pair production cross section is six orders of magnitude larger than that for t{bar t} production. Even including the full signature of hadronic t{bar t} decays, two b-jets and four additional jets, the QCD cross section for processes with similar signature is more than five times larger than for t{bar t} production. The presence of isolated leptons in the (semi)leptonic t{bar t} decay channels provides a clear characteristic to distinguish the t{bar t} signal from QCD background but introduces a multitude of W- and Z-related backgrounds.

  1. 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; Alvarez Gonzalez, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A

    2011-10-14

    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.

  2. 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.

    2011-10-14

    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

  3. 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.

    2011-10-14

    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 tt̄ 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 amore » 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 + ΔJES) ± 1.3 (syst) GeV/c2.« less

  4. Measurement of the Top Quark Mass and ppbar -> ttbar Cross Section in the All-Hadronic Mode with the CDFII Detector

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.; Apresyan, A.; /Purdue U. /Waseda U.

    2010-02-01

    We present a measurement of the top quark mass and of the top-antitop pair production cross section using p{bar p} data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9 fb{sup -1}. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8 {+-} 2.4(stat+JES){sub -1.0}{sup +1.2}(syst)GeV/c{sup 2}, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure measures also the amount of signal from which we derive a cross section, {sigma}{sub t{bar t}} = 7.2 {+-} 0.5(stat) {+-} 1.0(syst) {+-} 0.4(lum) pb, for the measured values of top quark mass and JES.

  5. Measurement of the top-quark mass in all-jets $$t\\bar{t}$$ events in pp collisions at $$\\sqrt{s}$$=7 TeV

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

    Chatrchyan, Serguei

    2013-07-17

    The mass of the top quark is measured using a sample ofmore » $$t\\bar{t}$$ candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at $$\\sqrt{s}$$ = 7 TeV in 2011 and corresponds to an integrated luminosity of 3.54 inverse femtobarns. The mass is reconstructed for each event employing a kinematic fit of the jets to a $$t\\bar{t}$$ hypothesis. The top-quark mass is measured to be 173.49 $$\\pm$$ 0.69 (stat.) $$\\pm$$ 1.21 (syst.) GeV. A combination with previously published measurements in other decay modes by CMS yields a mass of 173.54 $$\\pm$$ 0.33 (stat.) $$\\pm$$ 0.96 (syst.) GeV.« less

  6. Measurement of the top quark mass in the tt? lepton+jets and tt? dilepton channels using ?s = 7 TeV ATLAS data

    SciTech Connect (OSTI)

    Aad, G.

    2015-07-17

    The top quark mass was measured in the channels tt? lepton+jets and tt? dilepton (lepton = e,?) based on ATLAS data recorded in 2011. The data were taken at the LHC with a protonproton centre-of-mass energy of ?s = 7 TeV and correspond to an integrated luminosity of 4.6 fb1. The tt? lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks or gluons, respectively. The analysis of the tt? dilepton channel exploits a one-dimensional template method using the m?b observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 0.75 (stat + JSF + bJSF) 1.02(syst) GeV, and 173.79 0.54(stat) 1.30(syst) GeV in the tt? lepton+jets and tt? dilepton channels, respectively. Thus, the combination of the two results yields mtop = 172.99 0.48(stat) 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.

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

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; /Purdue U. /Waseda U.

    2009-01-01

    We present a measurement of the top quark mass with t{bar t} dilepton events produced in p{bar p} collisions at the Fermilab Tevatron ({radical}s = 1.96 TeV) and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb{sup -1}, are selected as t{bar t} candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ({phi}{sub {nu}1}, {phi}{sub {nu}2}) of neutrinos and reconstruct the top quark mass for each {phi}{sub {nu}1}, {phi}{sub {nu}2} pair by minimizing a {chi}{sup 2} function in the t{bar t} dilepton hypothesis. We assign {chi}{sup 2}-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t{bar t} and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of 165.5{sub -3.3}{sup +3.4}(stat.){+-}3.1(syst.) GeV/c{sup 2}.

  8. Press Pass - Press Release - Single top quark

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

    Higgs." Discovering the single top quark production presents challenges similar to the Higgs boson search in the need to extract an extremely small signal from a very large...

  9. 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

    2012-02-14

    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.

  10. Measurement of the Top Quark Mass in p anti-p Collisions at s**(1/2) = 1.96-TeV using the Decay Length Technique

    SciTech Connect (OSTI)

    Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara /Cantabria Inst. of Phys.

    2006-12-01

    We report the first measurement of the top quark mass using the decay length technique in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. This technique uses the measured flight distance of the b hadron to infer the mass of the top quark in lepton plus jets events with missing transverse energy. It relies solely on tracking and avoids the jet energy scale uncertainty that is common to all other methods used so far. We apply our novel method to a 695 pb{sup -1} data sample recorded by the CDF II detector at Fermilab and extract a measurement of m{sub t} = 180.7{sub -13.4}{sup +15.5}(stat.) {+-} 8.6 (syst.) GeV/c{sup 2}. While the uncertainty of this result is larger than that of other measurements, the dominant uncertainties in the decay length technique are uncorrelated with those in other methods. This result can help reduce the overall uncertainty when combined with other existing measurements of the top quark mass.

  11. Top quark and SUSY (supersymmetric) searches at CDF

    SciTech Connect (OSTI)

    Yeh, G.P.

    1990-05-17

    Searches for the top quark in p{bar p} collisions at {radical}s = 1.8 TeV are described. The analyses are based on data with an integrated luminosity of 4.4 pb{sup {minus}1} recorded with the Collider Detector at Fermilab in the 1988--1989 run. An upper limit on the t{bar t} cross section is obtained. The top quark with mass below 89 GeV/c{sup 2} is excluded at the 95% CL. Prospects for searches for the top quark in the future are presented. We also briefly present results on searches for supersymmetric particles. 14 refs., 10 figs.

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

    SciTech Connect (OSTI)

    Triplett, Nathan; /Iowa State U.

    2011-04-01

    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. Top quark anomalous couplings at the International Linear Collider...

    Office of Scientific and Technical Information (OSTI)

    Top quark anomalous couplings at the International Linear Collider Citation Details In-Document Search Title: Top quark anomalous couplings at the International Linear Collider ...

  14. Four top quarks in extensions of the standard model (Journal...

    Office of Scientific and Technical Information (OSTI)

    Four top quarks in extensions of the standard model Citation Details In-Document Search Title: Four top quarks in extensions of the standard model Authors: Grgoire, Thomas ; ...

  15. Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \\textit{in situ} Jet Energy Calibration

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2010-10-01

    A precision measurement of the top quark mass m{sub t} is obtained using a sample of t{bar t} events from p{bar p} collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m{sub t} and a parameter {Delta}{sub JES} used to calibrate the jet energy scale in situ. Using a total of 1087 events, a value of m{sub t} = 173.0 {+-} 1.2 GeV/c{sup 2} is measured.

  16. Measurement of the top-quark mass in all-hadronic decays in p anti-p collisions at CDF II

    SciTech Connect (OSTI)

    Aaltonen, T.; Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Fermilab /Frascati

    2006-12-01

    We present a measurement of the top-quark mass, M{sub tpo}, in the all-hadronic decay channel t{bar t} {yields} W{sup +}bW{sup -}{bar b} {yields} q{sub 1}{bar q}{sub 2}bq{sub 3}{bar q}{sub 4}{bar b}. The analysis is performed using 310 pb{sup -1} of {radical}s = 1.96 TeV p{bar p} collisions collected with the CDF II detector using a multi-jet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value of M{sub top} = 177.1 {+-} 4.9(stat.) {+-} 4.7(syst.) GeV/c{sup 2}.

  17. Dark decay of the top quark

    SciTech Connect (OSTI)

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

    2014-04-01

    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. In addition, we discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.

  18. 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

    2007-09-30

    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}.

  19. Improved determination of the width of the top quark

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott B.; Acharya B. S.; Adams M.; Adams T.; Alexeev G. D.; Alkhazov G.; Alton A.; Alverson G.; Aoki M.; Askew A.; Asman B.; Atkins S.; Atramentov O.; Augsten K.; 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.; Bean A.; Begalli M.; Belanger-Champagne C.; Bellantoni L.; Beri S. B.; Bernardi G.; Bernhard R.; Bertram I.; Besancon M.; Beuselinck R.; Bezzubov V. A.; Bhat P. C.; Bhatia S.; Bhatnagar V.; Blazey G.; Blessing S.; Bloom K.; Boehnlein A.; Boline D.; 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-Perez E.; Carrasco-Lizarraga M. A.; Casey C. K.; Castilla-Valdez H.; Chakrabarti S.; Chakraborty D.; Chan M.; Chandra A.; Chapon E.; Chen G.; Chevalier-Thery S.; Cho D. K.; Cho S. W.; Choi S.; Choudhary B.; Cihangir S.; Claes D.; Clutter J.; Cooke M.; Cooper W. E.; Corcoran M.; Couderc F.; Cousinou M. -C.; Croc A.; Cutts D.; Das A.; Davies G.; de Jong S. J.; De La Cruz-Burelo E.; Deliot F.; Demina R.; Denisov D.; Denisov S. P.; Desai S.; Deterre C.; DeVaughan K.; Diehl H. T.; Diesburg M.; Ding P. F.; 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.; Garcia-Bellido A.; Garcia-Guerra G. A.; Gavrilov V.; Gay P.; Geng W.; Gerbaudo D.; Gerber C. E.; Gershtein Y.; Ginther G.; Golovanov G.; Goussiou A.; Graf C. P.; Grannis P. D.; Greder S.; Greenlee H.; Greenwood Z. D.; Gregores E. M.; Grenier G.; Gris Ph.; Grivaz J. -F.; Grohsjean A.; Gruenendahl S.; Gruenewald M. W.; Guillemin T.; 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.; La Cruz I. Heredia-De; Herner K.; Hesketh G.; Hildreth M. D.; Hirosky R.; Hoang T.; Hobbs J. D.; Hoeneisen B.; Hohlfeld M.; Hubacek Z.; Hynek V.; Iashvili I.; Ilchenko Y.; Illingworth R.; Ito A. S.; Jabeen S.; Jaffre M.; Jamin D.; Jayasinghe A.; Jesik R.; Johns K.; Johnson M.; Jonckheere A.; Jonsson P.; Joshi J.; Jung A. W.; 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.; Kohli J. M.; Kozelov A. V.; Kraus J.; Kulikov S.; Kumar A.; Kupco A.; Kurca T.; Kuzmin V. A.; Lammers S.; Landsberg G.; Lebrun P.; Lee H. S.; Lee S. W.; Lee W. M.; Lellouch J.; Li H.; Li L.; Li Q. Z.; Lietti S. M.; Lim J. K.; Lincoln D.; Linnemann J.; Lipaev V. V.; Lipton R.; Liu Y.; Lobodenko A.; Lokajicek M.; de Sa R. Lopes; Lubatti H. J.; Luna-Garcia R.; Lyon A. L.; Maciel A. K. A.; Mackin D.; Madar R.; Magana-Villalba R.; Malik S.; Malyshev V. L.; Maravin Y.; Martinez-Ortega J.; McCarthy R.; McGivern C. L.; Meijer M. M.; Melnitchouk A.; Menezes D.; Mercadante P. G.; Merkin M.; et al.

    2012-05-04

    We present an improved determination of the total width of the top quark, {Gamma}{sub t}, using 5.4 fb{sup -1} of integrated luminosity collected by the D0 Collaboration at the Tevatron p{bar p} Collider. The total width {Gamma}{sub t} is extracted from the partial decay width {Gamma}(t {yields} Wb) and the branching fraction {Beta}(t {yields} Wb). {Gamma}(t {yields} Wb) is obtained from the t-channel single top-quark production cross section and {Beta}(t {yields} Wb) is measured in t{bar t} events. For a top mass of 172.5 GeV, the resulting width is {Gamma}{sub t} = 2.00{sub -0.43}{sup +0.47} GeV. This translates to a top-quark lifetime of {tau}{sub t} = (3.29{sub -0.63}{sup +0.90}) x 10{sup -25} s. We also extract an improved direct limit on the Cabibbo-Kobayashi-Maskawa quark-mixing matrix element 0.81 < |V{sub tb}| {le} 1 at 95% C.L. and a limit of |V{sub tb}| < 0.59 for a high-mass fourth-generation bottom quark assuming unitarity of the fourth-generation quark-mixing matrix.

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

    SciTech Connect (OSTI)

    Benitez, Jorge Armando; /Michigan State U.

    2009-08-01

    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.

  1. Neural Networks for Analysis of Top Quark Production

    SciTech Connect (OSTI)

    B. Abbott et al.

    1999-08-04

    Neural networks (NNs) provide a powerful and flexible tool for selecting a signal from a larger background. The D0 collaboration has used them extensively in studying t{anti t} decays. NNs were essential to the measurement of the t{anti t} production cross section in the all-jets channel (t{anti t} {yields} b {anti b}qqqq), and were also used in the measurement of the mass of the top quark in the lepton+jets channel (t{anti t} {yields} b{anti b}l{nu}q{anti q}). This paper will describe two new applications of neural networks to top quark analysis: the search for single top quark production, and an effort to increase the sensitivity in the dilepton channel t{anti t} {yields} b{anti b}e{anti {mu}}{nu}{anti {nu}} beyond that achieved in the published analysis.

  2. The heavy Top Quark Partner in Little Higgs Models

    SciTech Connect (OSTI)

    Larios, F.; Perez, M. A.; Penunuri, F.

    2008-07-02

    Little Higgs models provide a natural explanation for the lightness of the Higgs mass. Through the mechanism of collective symmetry breaking, one loop quadratic divergent contributions to the Higgs mass are avoided. In these models a heavy partner of the Top quark appears as required to cancel out the Top's loop contribution. This heavy Top could be produced at the LHC mainly in the single mode. Because of flavor mixing a large FCNC gtT coupling can be generated at one loop that could boost the single T production mode through gg fusion.

  3. Measurement of the top quark pair production cross section in...

    Office of Scientific and Technical Information (OSTI)

    Measurement of the top quark pair production cross section in proton-proton collisions at sqrts13 TeV Citation Details In-Document Search Title: Measurement of the top quark...

  4. Dark decay of the top quark

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

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

    2014-04-01

    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 σ 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 topmore » 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. In addition, we discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.« less

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

    SciTech Connect (OSTI)

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

    2011-08-15

    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.

  6. Top quark properties from the Tevatron (Conference) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Top quark properties from the Tevatron Citation Details In-Document Search Title: Top quark properties from the Tevatron 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

  7. Top quark physics at the Tevatron results and prospects

    SciTech Connect (OSTI)

    K. Sliwa

    2002-10-16

    The methodology of CDF and D0 top quark analyses and their underlying assumptions are summarized. The CDF and D0 top mass averages, obtained from measurements in several channels and based on about 100 pb{sup -1} of data from p{bar p} collisions at {radical}s = 1.8 TeV collected by each experiment in Run-I, are: M{sub t} = 176.1 {+-} 4.0(stat) {+-} 5.1(syst) GeV/c{sup 2} and M{sub t} = 172.1 {+-} 5.2(stat) {+-} 4.9(syst) Gev/C{sup 2}, respectively. The combined Tevatron measurement of the top quark mass is M{sub t} = 174.3 {+-} 3.2(stat) {+-} 4.0(syst) GeV/c{sup 2}. The CDF measurement of the t{bar t} cross section (assuming M{sub t} = 175 GeV/c{sup 2}) is {sigma}{sub tt} = 6.5 {+-} {sub 1.4}{sup 1.6} pb, and the D0 value (assuming M{sub t} = 172.1 GeV/c{sup 2}) is {sigma}{sub tt} = 5.9 {+-} 1.7 pb. In anticipation of much larger statistics, prospects for top physics in Tevatron Run-II are summarized. The fact that top quark analyses are among the best windows to physics beyond the Standard Model is emphasized.

  8. Rare top quark decays in extended models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O. G.; Cabral-Rosetti, L. G.

    2006-09-25

    Flavor changing neutral currents (FCNC) decays t {yields} H0 + c, t {yields} Z + c, and H0 {yields} t + c-bar are discussed in the context of Alternative Left-Right symmetric Models (ALRM) with extra isosinglet heavy fermions where FCNC decays may take place at tree-level and are only suppressed by the mixing between ordinary top and charm quarks, which is poorly constraint by current experimental values. The non-manifest case is also briefly discussed.

  9. 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

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

    Chatrchyan, Serguei

    2014-08-21

    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,more » $$m_t^{pole}$$, or the strong coupling constant, $$\\alpha_S$$. With the parton distribution function set NNPDF2.3, a pole mass of 176.7$$^{+3.0}_{-2.8}$$ GeV is obtained when constraining $$\\alpha_S$$ at the scale of the Z boson mass, $m_Z$, to the current world average. Alternatively, by constraining $$m_t^{pole}$$ to the latest average from direct mass measurements, a value of $$\\alpha_S(m_Z)$$ = 0.1151$$^{+0.0028}_{-0.0027}$$ is extracted. This is the first determination of $$\\alpha_S$$ using events from top-quark production.« less

  10. Measurement of the top quark mass in the tt¯→ lepton+jets and tt¯→ dilepton channels using √s = 7   TeV ATLAS data

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

    Aad, G.

    2015-07-17

    The top quark mass was measured in the channels tt¯→ lepton+jets and tt¯→ dilepton (lepton = e,μ) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton–proton centre-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of 4.6 fb–1. The tt¯→ lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks ormore » gluons, respectively. The analysis of the tt¯→ dilepton channel exploits a one-dimensional template method using the mℓb observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 ± 0.75 (stat + JSF + bJSF) ± 1.02(syst) GeV, and 173.79 ± 0.54(stat) ± 1.30(syst) GeV in the tt¯→ lepton+jets and tt¯→ dilepton channels, respectively. Thus, the combination of the two results yields mtop = 172.99 ± 0.48(stat) ± 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.« less

  11. Measurement of the top quark mass in the tt¯→ lepton+jets and tt¯→ dilepton channels using √s = 7   TeV ATLAS data

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

    Aad, G.

    2015-07-17

    The top quark mass was measured in the channels tt¯→ lepton+jets and tt¯→ dilepton (lepton = e,μ) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton–proton centre-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of 4.6 fb–1. The tt¯→ lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks ormore »gluons, respectively. The analysis of the tt¯→ dilepton channel exploits a one-dimensional template method using the mℓb observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 ± 0.75 (stat + JSF + bJSF) ± 1.02(syst) GeV, and 173.79 ± 0.54(stat) ± 1.30(syst) GeV in the tt¯→ lepton+jets and tt¯→ dilepton channels, respectively. Thus, the combination of the two results yields mtop = 172.99 ± 0.48(stat) ± 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.« less

  12. Recent Results in the Top Quark Sector from the D0 Experiment (Conference)

    Office of Scientific and Technical Information (OSTI)

    | SciTech Connect Conference: Recent Results in the Top Quark Sector from the D0 Experiment Citation Details In-Document Search Title: Recent Results in the Top Quark Sector from the D0 Experiment In these proceedings, I review recent measurements in the top quark sector in pp-bar collisions at a centre-of-mass energy of √s = 1.96 TeV in Run II of the Fermilab Tevatron Collider using the D0 detector. I will present the differential measurement of the tt-bar production cross section and the

  13. VariableR reclustering in multiple top quark events - Oral Presentatio...

    Office of Scientific and Technical Information (OSTI)

    VariableR reclustering in multiple top quark events - Oral Presentation Citation Details In-Document Search Title: VariableR reclustering in multiple top quark events - Oral...

  14. Top quark production and properties at the Tevatron

    SciTech Connect (OSTI)

    Fiedler, Frank; /Munich U.

    2005-06-01

    The precise measurement of top quark production and properties is one of the primary goals of the Tevatron during Run II. The total t{bar t} production cross-section has been measured in a large variety of decay channels and using different selection criteria. Results from differential cross-section measurements and searches for new physics in t{bar t} production and top quark decays are available. Electroweak production of single top quarks has been searched for. The results from all these analyses, using typically 200 pb{sup -1} of data, are presented.

  15. A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2010-08-01

    We present a measurement of the top-quark width using t{bar t} events produced in p{bar p} collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a W boson and a bottom quark, we select events in which one W decays leptonically and the other hadronically (lepton + jets channel) . From a data sample corresponding to 4.3 fb{sup -1} of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of W boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths ({Lambda}{sub t}) and deviations from nominal jet energy scale ({Delta}{sub JES}) to perform a simultaneous fit for both parameters, where {Delta}{sub JES} is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of {Lambda}{sub t} < 7.6 GeV and a two-sided 68% CL interval of 0.3 GeV < {Lambda}{sub t} < 4.4 GeV for a top-quark mass of 172.5 GeV/c{sup 2}, which are consistant with the standard model prediction. This is the first direct measurement of {Lambda}{sub t} to set a lower limit with 68% CL.

  16. Evidence for electroweak top quark production in proton-antiproton...

    Office of Scientific and Technical Information (OSTI)

    acceptance, background, and observed data we measure the single top quark cross section: sigma(pbar p yields tb + tqb + X) 4.6sub -1.5sup +1.8 pb. The probability for...

  17. Top quark properties from the Tevatron (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    precision top quark measurements. Authors: Klute, Markus ; MIT, LNS Publication Date: 2006-05-01 OSTI Identifier: 892334 Report Number(s): FERMILAB-CONF-06-114-E arXiv eprint...

  18. The top quark (20 years after the discovery)

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

    Boos, Eduard; Brandt, Oleg; Denisov, Dmitri; Denisov, Sergey; Grannis, Paul

    2015-09-10

    On the twentieth anniversary of the observation of the top quark, we trace our understanding of this heaviest of all known particles from the prediction of its existence, through the searches and discovery, to the current knowledge of its production mechanisms and properties. We also discuss the central role of the top quark in the Standard Model and the windows that it opens for seeking new physics beyond the Standard Model.

  19. Top Quark Anomalous Couplings at the International Linear Collider (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Top Quark Anomalous Couplings at the International Linear Collider Citation Details In-Document Search Title: Top Quark Anomalous Couplings at the International Linear Collider × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and

  20. Top quark anomalous couplings at the International Linear Collider (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Top quark anomalous couplings at the International Linear Collider Citation Details In-Document Search Title: Top quark anomalous couplings at the International Linear Collider Authors: Devetak, Erik ; Nomerotski, Andrei ; Peskin, Michael Publication Date: 2011-08-17 OSTI Identifier: 1100572 Type: Publisher's Accepted Manuscript Journal Name: Physical Review D Additional Journal Information: Journal Volume: 84; Journal Issue: 3; Journal ID: ISSN 1550-7998

  1. Study of anomalous top quark flavor-changing neutral current interactions via the tW channel of single-top-quark production

    SciTech Connect (OSTI)

    Etesami, S. M.; Mohammadi Najafabadi, M.

    2010-06-01

    The potential of the LHC for investigation of anomalous top quark interactions with gluon (tug,tcg) through the production of tW channel of single top quarks is studied. In the standard model, the single top quarks in the tW-channel mode are charge symmetric, meaning that {sigma}(pp{yields}t+W{sup -})={sigma}(pp{yields}t+W{sup +}). However, the presence of anomalous flavor-changing neutral current (FCNC) couplings leads to charge asymmetry. In this paper, a method is proposed in which this charge asymmetry may be used to constrain anomalous FCNC couplings. The strength of resulting constraints is estimated for the LHC for the center of mass energies of 7 and 14 TeV.

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

    SciTech Connect (OSTI)

    Khanov, Alexander

    2013-12-11

    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.

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

    SciTech Connect (OSTI)

    Batebi, S.; Etesami, S. M.; Mohammadi-Najafabadi, M.

    2011-03-01

    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.

  4. Search for pair production of excited top quarks in the lepton + jets final state

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

    Chatrchyan, Serguei

    2014-11-19

    A search is performed for pair-produced spin-3/2 excited top quarks t*t ¯* , each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of √s = 8 TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb-1, show no significant excess over standard model predictions, and provide a lowermore » limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t* quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. As a result, this is the first search for a spin-3/2 excited top quark performed at the LHC.« less

  5. Search for pair production of excited top quarks in the lepton + jets final state

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; et al.

    2013-11-21

    A search is performed for pair-produced spin-3/2 excited top quarks t*t * , each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of ?s = 8 TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb-1, show no significant excess over standard model predictions, and provide a lower limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t(*) quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. This is the first search for a spin-3/2 excited top quark performed at the LHC.

  6. Search for baryon number violation in top-quark decays

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

    Chatrchyan, Serguei

    2014-02-20

    A search for baryon number violation (BNV) in top-quark decays is performed using pp collisions produced by the LHC at sqrt(s) = 8 TeV. The top-quark decay considered in this search results in one light lepton (muon or electron), two jets, but no neutrino in the final state. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 19.5 inverse femtobarns. The event selection is optimized for top quarks produced in pairs, with one undergoing the BNV decay and the other the standard model hadronic decay to three jets. No significant excessmore » of events over the expected yield from standard model processes is observed. The upper limits at 95% confidence level on the branching fraction of the BNV top-quark decay are calculated to be 0.0016 and 0.0017 for the muon and the electron channels, respectively. Assuming lepton universality, an upper limit of 0.0015 results from the combination of the two channels. These limits are the first that have been obtained on a BNV process involving the top quark.« less

  7. Search for Electroweak Single-Top Quark Production with the CDF II Experiment

    SciTech Connect (OSTI)

    Buehler, Matthias; /Karlsruhe U., EKP

    2006-08-01

    The CDF II experiment and the Tevatron proton-antiproton collider are parts of the Fermi National Laboratories (Fermilab). The Fermilab is located in the vicinity of Chicago, USA. Today, the Tevatron is the only collider which is able to produce the heaviest known elementary particle, the top quark. The top quark was discovered at the Tevatron by the CDF and the D0 collaborations in 1995 [1]. So far, all the top quarks found are produced via the strong interaction as top-antitop pairs. The Standard Model of elementary particle physics also predicts single-top quark production via the electroweak interaction. This production mode has not yet been observed. The CDF and the D0 collaborations have set upper limits on the cross section for that process in Run I [2, 3] and improved those results in Run II [4, 5]. Single-top quark production is one of the major interests in Run II of the Tevatron as it offers several ways to test the Standard Model and to search for potential physics beyond the Standard Model. The measurement of the cross section of singly produced top quarks via the electroweak interaction offers the possibility to determine the Cabbibo-Kobayashi-Maskawa (CKM) matrix element V{sub tb} directly. The CKM matrix defines the transformation from the eigenstates of the electroweak interactions to the mass eigenstates of the quarks. V{sub tb} gives the strength of the coupling at the Wtb vertex. The single-top quark is produced at this vertex and therefore the cross section of the single-top quark production is directly proportional to |V{sub tb}|{sup 2}. In the Standard Model, three generations of quarks and the unitarity of the CKM matrix are predicted. This leads to V{sub tb} {approx} 1. Up to now, there is no possibility to measure V{sub tb} without using the assumption that there are a certain number of quark generations. Since the measurement of the cross section of single-top quark production is independent of this assumption it could verify another prediction of the Standard Model or give hints towards physics beyond the Standard Model such as a fourth generation of quarks. In addition, electroweak single-top quark production is an important background for the Higgs boson search in the mass range of 90 GeV/c{sup 2} to 130 GeV/c{sup 2} at the Tevatron in the WH channel. Two single-top quark production modes are dominant at the Tevatron, the t-channel or W-gluon fusion and the s-channel or W* process. Since it is challenging to separate the signal from the various background events we use a neural network to combine several variables into one powerful discriminant. The simulated Monte Carlo sample outputs of the neural networks are used as templates for a likelihood fit to the outputs of the neural networks of the data. In this thesis CDF II data corresponding to an integrated luminosity of 695 pb{sup -1} is discussed. As this analysis yields no significant evidence of electroweak single-top production it is not possible to measure any cross sections. Consequently we determine upper limits on the cross sections of the t- and s-channel production separately and combined.

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

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

    Demina, Regina; Harel, Amnon; Orbaker, Douglas

    2015-04-02

    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.

  9. Top Quark Anomalous Couplings at the International Linear Collider (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Quark Anomalous Couplings at the International Linear Collider Citation Details In-Document Search Title: Top Quark Anomalous Couplings at the International Linear Collider We present a study of the experimental determination of the forward-backward asymmetry in the process e{sup +}e{sup -} {yields} t{bar t} and in the subsequent t {yields} Wb decay, studied in the context of the International Linear Collider. This process probes the elementary couplings of the top

  10. 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.

    2010-09-01

    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.

  11. Quark mass variation constraints from Big Bang nucleosynthesis...

    Office of Scientific and Technical Information (OSTI)

    Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis We study...

  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.

    2011-12-12

    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

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Aoki, M.; Arov, M.; Askew, A.; Asman, 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.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; 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-Perez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; 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.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; 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.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; 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.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffre, M.; Jamin, D.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; 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.; Kirby, M. H.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, 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.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; 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.; Orbaker, D.; Orduna, J.; Osman, N.; Osta, J.; et. al.

    2011-12-12

    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 data set corresponding to an integrated luminosity of 5.4 fb{sup -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.

  14. Why should we care about the top quark Yukawa coupling?

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

    Shapshnikov, Mikhail; Bezrukov, Fedor

    2015-04-15

    In the cosmological context, for the Standard Model to be valid up to the scale of inflation, the top quark Yukawa coupling yt should not exceed the critical value ytcrit , coinciding with good precision (about 0.2‰) with the requirement of the stability of the electroweak vacuum. So, the exact measurements of yt may give an insight on the possible existence and the energy scale of new physics above 100 GeV, which is extremely sensitive to yt. In this study, we overview the most recent theoretical computations of and the experimental measurements of ytcrit and the experimental measurements ofmore » yt. Within the theoretical and experimental uncertainties in yt, the required scale of new physics varies from 10⁷ GeV to the Planck scale, urging for precise determination of the top quark Yukawa coupling.« less

  15. CP violating anomalous top-quark couplings at the LHC

    SciTech Connect (OSTI)

    Gupta, Sudhir Kumar; Mete, Alaettin Serhan; Valencia, G.

    2009-08-01

    We study the T odd correlations induced by CP violating anomalous top-quark couplings at both production and decay level in the process gg{yields}tt{yields}(b{mu}{sup +}{nu}{sub {mu}})(b{mu}{sup -}{nu}{sub {mu}}). We consider several counting asymmetries at the parton level and find the ones with the most sensitivity to each of these anomalous couplings at the LHC.

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

    SciTech Connect (OSTI)

    Bartos, Pavol; /Comenius U.

    2011-09-01

    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.

  17. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-06-12

    A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb? collected with the CMS detector in proton-proton collisions at ?s = 8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. Upper limits on the production cross section of a T quark with mass between 500 and 1000 GeV/c are derived. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.

  18. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-06-12

    We performed a search for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb-1collected with the CMS detector in proton-proton collisions at √s=8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. We also derived upper limits on the production cross section of a T quark with mass between 500 and 1000 GeV/c 2. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c 2 at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.

  19. Search for pair production of the scalar top quark in muon plus tau final states

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott B.; Acharya B. S.; Adams M.; Adams T.; Alexeev G. D.; Alkhazov G.; Alton A.; Alverson G.; Aoki M.; Askew A.; Asman B.; Atkins S.; Atramentov O.; Augsten K.; 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.; Bean A.; Begalli M.; Belanger-Champagne C.; Bellantoni L.; Beri S. B.; Bernardi G.; Bernhard R.; Bertram I.; Besancon M.; Beuselinck R.; Bezzubov V. A.; Bhat P. C.; Bhatia S.; Bhatnagar V.; Blazey G.; Blessing S.; Bloom K.; Boehnlein A.; Boline D.; 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-Perez E.; Carrasco-Lizarraga M. A.; Casey B. C. K.; Castilla-Valdez H.; Chakrabarti S.; Chakraborty D.; Chan K. M.; Chandra A.; Chapon E.; Chen G.; Chevalier-Thery S.; Cho D. K.; Cho S. W.; Choi S.; Choudhary B.; Cihangir S.; Claes D.; Clutter J.; Cooke M.; Cooper W. E.; Corcoran M.; Couderc F.; Cousinou M. -C.; Croc A.; Cutts D.; Das A.; Davies G.; de Jong S. J.; De La Cruz-Burelo E.; Deliot F.; Demina R.; Denisov D.; Denisov S. P.; Desai S.; Deterre C.; DeVaughan K.; Diehl H. T.; Diesburg M.; Ding P. F.; 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.; Garcia-Bellido A.; Garcia-Guerra G. A.; Gavrilov V.; Gay P.; 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.; Gruenendahl S.; Gruenewald M. W.; Guillemin T.; 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.; Hubacek Z.; Hynek V.; Iashvili I.; Ilchenko Y.; Illingworth R.; Ito A. S.; Jabeen S.; Jaffre M.; Jamin D.; Jayasinghe A.; Jesik R.; Johns K.; Johnson M.; Jonckheere A.; Jonsson P.; Joshi J.; Jung A. W.; 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.; Kohli J. M.; Kozelov A. V.; Kraus J.; Kulikov S.; Kumar A.; Kupco A.; Kurca T.; Kuzmin V. A.; Lammers S.; Landsberg G.; Lebrun P.; Lee H. S.; Lee S. W.; Lee W. M.; Lellouch J.; Li H.; Li L.; Li Q. Z.; Lietti S. M.; Lim J. K.; Lincoln D.; Linnemann J.; Lipaev V. V.; Lipton R.; Liu Y.; Lobodenko A.; Lokajicek M.; Lopes de Sa R.; Lubatti H. J.; Luna-Garcia R.; Lyon A. L.; Maciel A. K. A.; Mackin D.; Madar R.; Magana-Villalba R.; Malik S.; Malyshev V. L.; Maravin Y.; Martinez-Ortega J.; McCarthy R.; McGivern C. L.; Meijer M. M.; Melnitchouk A.; Menezes D.; Mercadante P. G.; Merkin M.; et al.

    2012-04-20

    We present a search for the pair production of scalar top quarks ({tilde t}{sub 1}), the lightest supersymmetric partners of the top quarks, in p{bar p} collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of 7.3 fb{sup -1} collected with the D0 experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}). We investigate final states arising from {tilde t}{sub 1}{ovr {tilde t}{sub 1}} {yields} b{bar b}{mu}{tau}{tilde {nu}}{tilde {nu}} and {tilde t}{sub 1}{ovr {tilde t}{sub 1}} {yields} b{bar b}{tau}{tau}{tilde {nu}}{tilde {nu}}. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (M{sub {tilde t}{sub 1}}, M{sub {tilde {nu}}}) plane.

  20. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

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

    Khachatryan, Vardan

    2015-06-12

    We performed a search for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb-1collected with the CMS detector in proton-proton collisions at √s=8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. We also derived upper limits on the production cross section of a T quarkmore » with mass between 500 and 1000 GeV/c 2. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c 2 at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.« less

  1. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

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

    Khachatryan, V.

    2015-06-12

    A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb? collected with the CMS detector in proton-proton collisions at ?s = 8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. Upper limits on the production cross section of a T quarkmorewith mass between 500 and 1000 GeV/c are derived. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.less

  2. 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.

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

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

    Abazov, Victor Mukhamedovich

    2011-12-12

    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)%.more » 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.« less

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

    SciTech Connect (OSTI)

    Black, Kevin

    2013-07-29

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

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

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-03-01

    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.

  6. Quark mass variation constraints from Big Bang nucleosynthesis (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a

  7. Quark mass variation constraints from Big Bang nucleosynthesis (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Journal Article: Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and

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

    SciTech Connect (OSTI)

    Johnson, William Casey; /UC, Davis

    2010-05-01

    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}).

  9. Search for resonances decaying to top and bottom quarks with the CDF experiment

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero

    2015-08-03

    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 a center-of-mass energy of ?s = 1.96 TeV collected by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 fb1. No significant excess above the standard model 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 tb. Using a standard model extension with a W' ? tb and left-right-symmetric couplings as a benchmark model, we constrain the W' mass and couplings in the 300900 GeV/c2 range. As a result, the limits presented here are the most stringent for a charged resonance with mass in the range 300600 GeV/c2 decaying to top and bottom quarks.

  10. Measurement of the helicity of W bosons in top-quark decays

    SciTech Connect (OSTI)

    Abulencia, A. et al

    2006-06-01

    We measure the branching fraction of the top quark to longitudinally and right-handed polarized W bosons, F{sub 0} and F{sub +}, using approximately 200 pb{sup -1} of p{bar p} collisions collected by the CDF II detector. We analyze two quantities sensitive to the W helicity: the invariant mass of the charged lepton and the bottom-quark jet in the decay t {yields} Wb {yields} {ell}{nu}b (where {ell} = e or {mu}), and the transverse momentum of the charged lepton. We find F{sub 0} = 0.74{sub -0.34}{sup +0.22}, and F{sub +} < 0.27 at the 95% confidence level. These measurements are in agreement with the standard model predictions.

  11. Measurement of the W boson helicity in top quark decays

    SciTech Connect (OSTI)

    Gmyrek, Bryan David; /Arizona U.

    2007-08-01

    A measurement of the fraction, f{sup +}, of right-handed W bosons produced in top quark decays is presented. This analysis is based on a sample 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. The helicity angle, {theta}*, is reconstructed for each lepton. f{sup +} is determined by comparing the cos {theta}* distribution from the data with that for the expected background and signal for various values of f{sup +}. The fraction of longitudinal W bosons, f{sup 0}, is assumed to be 0.7 as predicted by the standard model. This yields f{sup +} = 0.109 {+-} 0.094 (stat) {+-} 0.063 (syst), consistent with the standard model prediction of f{sup +} = 3.6x 10{sup -4}. The possibility that both f{sup +} and f{sup 0} stray from standard model values is also investigated. In this case cos {theta}* distributions for each possible W helicity state, along with the backgrounds, are fit to the cos {theta}* distribution for the data. The best fit values are f{sup +} = 0.82 {+-} 0.30(stat) and f{sup 0} = -0.58 {+-} 0.50(stat).

  12. Electroweak production of top-quark pairs in e+e- annihilation at NNLO in

    Office of Scientific and Technical Information (OSTI)

    QCD: The vector current contributions (Journal Article) | SciTech Connect Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: The vector current contributions Citation Details In-Document Search Title: Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: The vector current contributions We report on a calculation of the vector current contributions to the electroweak production of top quark pairs in e+e- annihilation at

  13. Erratum to: Constraining couplings of top quarks to the Z boson in $

    Office of Scientific and Technical Information (OSTI)

    t\overline{t} $ + Z production at the LHC (Journal Article) | SciTech Connect Erratum to: Constraining couplings of top quarks to the Z boson in $ t\overline{t} $ + Z production at the LHC Citation Details In-Document Search Title: Erratum to: Constraining couplings of top quarks to the Z boson in $$ t\overline{t} $$ + Z production at the LHC We study top quark pair production in association with a Z boson at the Large Hadron Collider (LHC) and investigate the prospects of measuring the

  14. Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector

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

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

    2016-01-29

    A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton–proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb–1 are used. Furthermore, candidate events for a top quark decaying into a lepton, a neutrino and a jet are selected and classified into signal- and background-like candidates using a neural network.

  15. Effect of top quark spin on the Wtb couplings in e{sup +}p collisions

    SciTech Connect (OSTI)

    Atag, S.; Sahin, B.

    2006-04-01

    In our previous work [Phys. Rev. D 70, 037503 (2004)] for the e{sup +}p{yields}t{nu}+X process, we have shown that the top quark possesses a high degree of spin polarization when its spin decomposition axis is along the incoming lepton beam. In this work, the potential of ep collisions to probe an anomalous Wtb vertex is investigated via the polarized single top quark production process for TESLA+HERAp energy. The effects of the top quark polarization to Wtb couplings F{sub 2L} and F{sub 2R} are discussed. It is possible to define a polarization axis for the top quark that is more sensitive to new physics than the unpolarized case.

  16. VariableR Reclustering in Multiple Top Quark and W Boson Events

    SciTech Connect (OSTI)

    Hyde, Jeremy

    2015-08-14

    VariableR jet reclustering is an innovative technique that allows for the reconstruction of boosted object over a wide range of kinematic regimes. Such capability enables the efficient identification of events with multiple boosted top quarks which is a typical signature for new physics processes such as the production of the supersymmetric partner of the gluon. In order to evaluate the performance of the algorithm, the VariableR reclustered jets are compared with fixed radius reclustered jets. The flexibility of the algorithm is tested by reconstructing both boosted top quarks and boosted W bosons. The VariableR reclustering method is found to be more efficient than the fixed radius algorithm at identifying top quarks and W bosons in events with four top quarks, therefore enhancing the sensitivity for gluino searches.

  17. Electroweak production of top-quark pairs in e+e- annihilation...

    Office of Scientific and Technical Information (OSTI)

    Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: the vector contributions Citation Details In-Document Search Title: Electroweak production of...

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

    SciTech Connect (OSTI)

    Creutz, Michael

    2013-12-15

    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.

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

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-09-16

    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.

  20. 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

    2014-09-16

    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

  1. Top physics: search for electroweak single top quark production in p anti-p collisions at s**(1/2) = 1.96 tev

    SciTech Connect (OSTI)

    Acosta, D.; The CDF Collaboration

    2005-01-12

    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.

  2. Search for invisible particles produced in association with single-top-quarks in protonproton collisions at ?s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2015-02-18

    A search for the production of single-top-quarks in association with missing energy is performed in protonproton collisions at a centre-of-mass energy of ?s=8 TeV with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of 20.3 fb-1. In this study, the W boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association with a right-handed top quark. In the case of resonant production, for a spin-0 resonance with a mass of 500 GeV, an effective coupling strength above 0.15 is excluded at 95% confidence level for the top quark and an invisible spin-1/2 state with mass between 0 and 100 GeV. In the case of non-resonant production, an effective coupling strength above 0.2 is excluded at 95% confidence level for the top quark and an invisible spin-1 state with mass between 0 and 657 GeV.

  3. 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

    2015-04-08

    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⁻¹. 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=0.38±0.04, in agreement with the standard model prediction. A search is performed for pair production of topmore » 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.« less

  4. Measurement of single top quark production at D0 using a matrix element method

    SciTech Connect (OSTI)

    Mitrevski, Jovan Pavle; /Columbia U.

    2007-07-01

    Until now, the top quark has only been observed produced in pairs, by the strong force. According to the standard model, it can also be produced singly, via an electroweak interaction. Top quarks produced this way provide powerful ways to test the charged-current electroweak interactions of the top quark, to measure |V{sub tb}|, and to search for physics beyond the standard model. This thesis describes the application of the matrix element analysis technique to the search for single top quark production with the D0 detector using 0.9 fb{sup -1} of Run II data. From a comparison of the matrix element discriminants between data and the background model, assuming a Standard Model s-channel to t-channel cross section ratio of {sigma}{sub s}/{sigma}{sub t} = 0.44, we measure the single top quark production cross section: {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.8{sub -1.4}{sup +1.6} pb. This result has a p-value of 0.08%, corresponding to a 3.2 standard deviation Gaussian equivalent significance.

  5. Search for the Neutral Current Top Quark Decay t-->Zc Using Ratio of Z-Boson + 4 Jets to W-Boson + 4 Jets Production

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E.; Anastassov, A.; Annovi, Alberto; Antos, Jaroslav; Apollinari, G.; Apresyan, A.; /Purdue U. /Waseda U.

    2009-05-01

    We have used the Collider Detector at Fermilab (CDF II) to search for the flavor-changing neutral-current (FCNC) top quark decay t {yields} Zc using a technique employing ratios of W and Z production, measured in p{bar p} data corresponding to an integrated luminosity of 1.52 fb{sup -1}. The analysis uses a comparison of two decay chains, p{bar p} {yields} t{bar t} {yields} WbWb {yields} {ell}{nu}bjjb and p{bar p} {yields} t{bar t} {yields} ZcWb {yields} {ell}{ell}cjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the modeling of acceptance and efficiency for lepton identification over the multi-year dataset using another ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z bosons. To improve the discrimination against standard model backgrounds to top quark decays, we calculate the top quark mass for each event with two leptons and four jets assuming it is a t{bar t} event with one of the top quarks decaying to Zc. For additional background discrimination we require at least one jet to be identified as originating from a b-quark. No significant signal is found and we set an upper limit on the FCNC branching ratio Br(t {yields} Zc) using a likelihood constructed from the {ell}{ell}cjjb top quark mass distribution and the number of {ell}{nu}bjjb events. Limits are set as a function of the helicity of the Z boson produced in the FCNC decay. For 100% longitudinally polarized Z bosons we find limits of 8.3% and 9.3% (95% C.L.) depending on the assumptions regarding the theoretical top quark pair production cross-section.

  6. Debye mass and heavy quark potential in a PNJL quark plasma

    SciTech Connect (OSTI)

    Jankowski, J. Blaschke, D.

    2012-07-15

    We calculate the Debye mass for the screening of the heavy quark potential in a plasma of massless quarks coupled to the temporal gluon background governed by the Polyakov loop potential within the PNJL model in RPA approximation. We give a physical motivation for a recent phenomenological fit of lattice data by applying the calculated Debye mass with its suppression in the confined phase due to the Polyakov loop to a description of the temperature dependence of the singlet free energy for QCD with a heavy quark pair at infinite separation. We compare the result to lattice data.

  7. Measurement of the charge asymmetry in highly boosted top-quark pair

    Office of Scientific and Technical Information (OSTI)

    production in s=8 TeV pp collision data collected by the ATLAS experiment (Journal Article) | SciTech Connect charge asymmetry in highly boosted top-quark pair production in s=8 TeV pp collision data collected by the ATLAS experiment Citation Details In-Document Search Title: Measurement of the charge asymmetry in highly boosted top-quark pair production in s = 8 TeV pp collision data collected by the ATLAS experiment Publication Date: 2016-05-01 OSTI Identifier: 1240040 Type: Published

  8. Recent Results in the Top Quark Sector from the D0 Experiment (Conference)

    Office of Scientific and Technical Information (OSTI)

    | SciTech Connect Recent Results in the Top Quark Sector from the D0 Experiment Citation Details In-Document Search Title: Recent Results in the Top Quark Sector from the D0 Experiment × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A paper copy

  9. Electroweak production of top-quark pairs in e + e - annihilation at NNLO

    Office of Scientific and Technical Information (OSTI)

    in QCD: The vector current contributions (Journal Article) | SciTech Connect Electroweak production of top-quark pairs in e + e - annihilation at NNLO in QCD: The vector current contributions Citation Details In-Document Search Title: Electroweak production of top-quark pairs in e + e - annihilation at NNLO in QCD: The vector current contributions Authors: Gao, Jun ; Zhu, Hua Xing Publication Date: 2014-12-17 OSTI Identifier: 1180238 Grant/Contract Number: SC0003870; DEAC0276SF00515 Type:

  10. Measurement of the charge asymmetry in highly boosted top-quark pair

    Office of Scientific and Technical Information (OSTI)

    production in s=8 TeV pp collision data collected by the ATLAS experiment (Journal Article) | DOE PAGES charge asymmetry in highly boosted top-quark pair production in s=8 TeV pp collision data collected by the ATLAS experiment Title: Measurement of the charge asymmetry in highly boosted top-quark pair production in s=8 TeV pp collision data collected by the ATLAS experiment Publication Date: 2016-05-01 OSTI Identifier: 1240040 Type: Published Article Journal Name: Physics Letters. Section B

  11. Top Quark Forward-Backward Asymmetry in e + e - Annihilation at

    Office of Scientific and Technical Information (OSTI)

    Next-to-Next-to-Leading Order in QCD (Journal Article) | SciTech Connect Top Quark Forward-Backward Asymmetry in e + e - Annihilation at Next-to-Next-to-Leading Order in QCD Citation Details In-Document Search Title: Top Quark Forward-Backward Asymmetry in e + e - Annihilation at Next-to-Next-to-Leading Order in QCD Authors: Gao, Jun ; Zhu, Hua Xing Publication Date: 2014-12-31 OSTI Identifier: 1180004 Grant/Contract Number: AC02-06CH11357; AC02-76SF00515 Type: Publisher's Accepted

  12. Top-Quark Decay at Next-to-Next-to-Leading Order in QCD (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect SciTech Connect Search Results Journal Article: Top-Quark Decay at Next-to-Next-to-Leading Order in QCD Citation Details In-Document Search Title: Top-Quark Decay at Next-to-Next-to-Leading Order in QCD Authors: Gao, Jun ; Li, Chong Sheng ; Zhu, Hua Xing Publication Date: 2013-01-24 OSTI Identifier: 1101939 Type: Publisher's Accepted Manuscript Journal Name: Physical Review Letters Additional Journal Information: Journal Volume: 110; Journal Issue: 4; Journal ID: ISSN

  13. Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at √s = 8 TeV with the ATLAS detector

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

    Aad, G.

    2015-08-20

    A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at \\( \\sqrt{s}=8 \\) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb–1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W bosonmore » and a b-quark \\( \\left(T\\overline{T}\\to Wb+\\mathrm{X}\\right) \\), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (\\( T\\overline{T}\\to Ht+X\\;\\mathrm{and}\\;B\\overline{B}\\to Hb+\\mathrm{X} \\) respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. In addition, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.« less

  14. Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at √s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2015-08-20

    A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at \\( \\sqrt{s}=8 \\) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb–1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark \\( \\left(T\\overline{T}\\to Wb+\\mathrm{X}\\right) \\), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (\\( T\\overline{T}\\to Ht+X\\;\\mathrm{and}\\;B\\overline{B}\\to Hb+\\mathrm{X} \\) respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. In addition, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.

  15. Quark mass variation constraints from Big Bang nucleosynthesis (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A

  16. 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.

    2008-05-01

    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.

  17. Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7  TeVusing 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

    2014-12-24

    Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6  fb⁻¹. Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured formore » the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.« less

  18. Quark mass functions and pion structure in Minkowski space

    SciTech Connect (OSTI)

    Biernat, Elmer P.; Gross, Franz L.; Pena, Maria Teresa; Stadler, Alfred

    2014-03-01

    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.

  19. Search for a Heavy Top-Like Quark in $p\\bar{p}$ Collisions at ${\\surd}s = 1.96$~TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-07-01

    We present the results of a search for pair production of a heavy top-like (t') quark decaying to W q final states using data corresponding to an integrated luminosity of 5.6 fb{sup -1} collected by the CDF II detector in p{anti p} collisions at {radical}{ovr s} = 1.96 TeV. We perform parallel searches for t' {yields} W b and t' {yields} W q (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t'{anti t}' production cross section and exclude a standard model fourth-generation t' quark decaying to W b (W q) with mass below 358 (340) GeV/c{sup 2} at 95% CL.

  20. Search for single top quark production in pbar p collisions at sqrt{s}=1.96 TeV in the missing transverse energy plus jets topology

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.; Apresyan, A.; /Purdue U. /Waseda U.

    2010-01-01

    We report a search for single top quark production with the CDF II detector using 2.1 fb{sup -1} of integrated luminosity of p{bar p} collisions at {radical}s = 1.96 TeV. The data selected consist of events characterized by large energy imbalance in the transverse plane and hadronic jets, and no identified electrons and muons, so the sample is enriched in W {yields} {tau}{nu} decays. In order to suppress backgrounds, additional kinematic and topological requirements are imposed through a neural network, and at least one of the jets must be identified as a b quark jet. We measure an excess of signal-like events in agreement with the standard model prediction, but inconsistent with a model without single top quark production by 2.1 standard deviations ({sigma}), with a median expected sensitivity of 1.4 {sigma}. Assuming a top quark mass of 175 GeV/c{sup 2} and ascribing the excess to single top quark production, the cross section is measured to be 4.9{sub -2.2}{sup +2.5} (stat+syst) pb, consistent with measurements performed in independent datasets and with the standard model prediction.

  1. Search for pair production of scalar top quarks decaying to a tau lepton and a b quark in 1.96 TeV ppbar collisions

    SciTech Connect (OSTI)

    Khotilovich, Vadim, G.; /Texas A-M

    2008-05-01

    I present the results of a search for pair production of scalar top quarks ({tilde t}{sub 1}) in an R-parity violating supersymmetric scenario using 322 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each {tilde t}{sub 1} decays into a {tau} lepton and a b quark, with branching ratio {beta}, 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 final selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared {sigma}({tilde t}{sub 1}{bar {tilde t}}{sub 1}) x {beta}{sup 2} as a function of the stop mass m({tilde t}{sub 1}). Assuming {beta} = 1, I set a 95% confidence level limit m({tilde t}{sub 1}) > 153 GeV=c{sup 2}. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a {tau} lepton and a b quark.

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

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki U. /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Akimoto, T.; /Tsukuba U.; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /Padua U. /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.

    2009-07-01

    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 corresponding to 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% upper limits on the top quark decay 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. The upper limits on {Beta}(t {yields} H{sup +}b) can also be used as model-independent limits on the decay branching ratio of top quarks to generic scalar charged bosons beyond the standard model.

  3. Top Quark Produced Through the Electroweak Force: Discovery Using the Matrix Element Analysis and Search for Heavy Gauge Bosons Using Boosted Decision Trees

    SciTech Connect (OSTI)

    Pangilinan, Monica; /Brown U.

    2010-02-01

    The top quark produced through the electroweak channel provides a direct measurement of the V{sub tb} element in the CKM matrix which can be viewed as a transition rate of a top quark to a bottom quark. This production channel of top quark is also sensitive to different theories beyond the Standard Model such as heavy charged gauged bosons termed W{prime}. This thesis measures the cross section of the electroweak produced top quark using a technique based on using the matrix elements of the processes under consideration. The technique is applied to 2.3 fb{sup -1} of data from the D0 detector. From a comparison of the matrix element discriminants between data and the signal and background model using Bayesian statistics, we measure the cross section of the top quark produced through the electroweak mechanism {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.30{sub -1.20}{sup +0.98} pb. The measured result corresponds to a 4.9{sigma} Gaussian-equivalent significance. By combining this analysis with other analyses based on the Bayesian Neural Network (BNN) and Boosted Decision Tree (BDT) method, the measured cross section is 3.94 {+-} 0.88 pb with a significance of 5.0{sigma}, resulting in the discovery of electroweak produced top quarks. Using this measured cross section and constraining |V{sub tb}| < 1, the 95% confidence level (C.L.) lower limit is |V{sub tb}| > 0.78. Additionally, a search is made for the production of W{prime} using the same samples from the electroweak produced top quark. An analysis based on the BDT method is used to separate the signal from expected backgrounds. No significant excess is found and 95% C.L. upper limits on the production cross section are set for W{prime} with masses within 600-950 GeV. For four general models of W{prime} boson production using decay channel W{prime} {yields} t{bar b}, the lower mass limits are the following: M(W{prime}{sub L} with SM couplings) > 840 GeV; M(W{prime}{sub R}) > 880 GeV or 890 GeV if the right-handed neutrino is lighter or heavier than W{prime}{sub R}; and M(W{prime}{sub L+R}) > 915 GeV.

  4. Measurement of the differential cross section for top quark pair production in pp collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-20

    The normalized differential cross section for top quark pair (tt) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb1. The measurements are performed in the lepton+jets (e/? +jets) and in the dilepton (e+e, ?+?, and e??) decay channels. The tt cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt system. The data are compared with several predictions from perturbative quantum chromodynamic up to approximate next-to-next-to-leading-order precision. Furthermore, no significant deviations are observed relative to the standard model predictions.

  5. Measurement of the charge asymmetry in top quark pair production in pp collisions at $\\sqrt{s}$ = 8 TeV using a template method

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-08-18

    The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 fb -1 were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is Ayc= [0.33_0.26 (stat)_0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.

  6. Measurement of the differential cross section for top quark pair production in pp collisions at $$\\sqrt{s}$$ = 8 TeV

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

    Khachatryan, Vardan

    2015-11-20

    The normalized differential cross section for top quark pair (tt¯) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb–1. The measurements are performed in the lepton+jets (e/μ +jets) and in the dilepton (e+e–, μ+μ–, and e±μ∓) decay channels. The tt¯ cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt¯ system. The data are compared with several predictions from perturbative quantum chromodynamic upmore » to approximate next-to-next-to-leading-order precision. Furthermore, no significant deviations are observed relative to the standard model predictions.« less

  7. Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

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

    Khachatryan, V.

    2015-06-09

    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5fb-1 collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8TeV. In order to separate the signal from the larger tt + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratiomorebetween the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, ?, relative to the standard model prediction for a Higgs boson mass of 125GeV. The observed (expected) exclusion limit at a 95 % confidence level is ?+1.6-1.5.less

  8. Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-06-09

    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5fb-1 collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8TeV. In order to separate the signal from the larger tt + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratio between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, ?, relative to the standard model prediction for a Higgs boson mass of 125GeV. The observed (expected) exclusion limit at a 95 % confidence level is ?<4.2 (3.3), corresponding to a best fit value ?^=1.2+1.6-1.5.

  9. Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

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

    Khachatryan, Vardan

    2015-06-09

    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5fb-1 collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8TeV. In order to separate the signal from the larger tt¯ + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratiomore » between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, μ, relative to the standard model prediction for a Higgs boson mass of 125GeV. The observed (expected) exclusion limit at a 95 % confidence level is μ < 4.2 (3.3), corresponding to a best fit value μ^ = 1.2+1.6-1.5.« less

  10. Rare top quark and Higgs boson decays in alternative left-right symmetric models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O.G.; Cabral-Rosetti, L.G.

    2005-08-01

    Top quark and Higgs boson decays induced by flavor-changing neutral currents (FCNC) are very much suppressed in the standard model. Their detection in colliders such as the Large Hadron Collider, Next Linear Collider, or Tevatron would be a signal of new physics. We evaluate the FCNC decays t{yields}H{sup 0}+c, t{yields}Z+c, and H{sup 0}{yields}t+c in the context of alternative left-right symmetric models with extra isosinglet heavy fermions; in this case, FCNC decays occur at tree level, and they are suppressed only by the mixing between ordinary top and charm quarks, which is poorly constrained by current experimental values. This provides the possibility for future colliders either to detect new physics or to improve present bounds on the parameters of the model.

  11. Rare top quark decays in Alternative Left-Right Symmetric Models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O. G.; Cabral-Rosetti, L. G.

    2007-06-19

    We evaluate the flavor changing neutral currents (FCNC) decay t {yields} H0 + c in the context of Alternative Left-Right symmetric Models (ALRM) with extra isosinglet heavy fermions; the FCNC decays may place at tree level and are only supressed by the mixing between ordinary top and charm quarks. We also comment on the decay process t {yields} c + {gamma}, which involves radiative corrections.

  12. Measurement of the mass difference between $t$ and $\\bar{t}$ quarks

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-03-01

    We present a direct measurement of the mass difference between t and {bar t} quarks using t{bar t} candidate events in the lepton+jets channel, collected with the CDF II detector at Fermilab's 1.96 TeV Tevatron p{bar p} Collider. We make an event by event estimate of the mass difference to construct templates for top quark pair signal events and background events. The resulting mass difference distribution of data is compared to templates of signals and background using a maximum likelihood fit. From a sample corresponding to an integrated luminosity of 5.6 fb{sup -1}, we measure a mass difference, {Delta}M{sub top} = M{sub t} - M{sub {bar t}} = -3.3 {+-} 1.4 (stat) {+-} 1.0 (syst) GeV/c{sup 2}, approximately two standard deviations away from the CPT hypothesis of zero mass difference. This is the most precise measurement of a mass difference between t and its {bar t} partner to date.

  13. 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.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2012-03-01

    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.

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

    SciTech Connect (OSTI)

    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.

    2012-05-01

    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.

  15. Search for invisible particles produced in association with single-top-quarks in proton–proton collisions at √s = 8 TeV with the ATLAS detector

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

    Aad, G.

    2015-02-18

    A search for the production of single-top-quarks in association with missing energy is performed in proton–proton collisions at a centre-of-mass energy of √s=8 TeV with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of 20.3 fb-1. In this study, the W boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association withmore » a right-handed top quark. In the case of resonant production, for a spin-0 resonance with a mass of 500 GeV, an effective coupling strength above 0.15 is excluded at 95% confidence level for the top quark and an invisible spin-1/2 state with mass between 0 and 100 GeV. In the case of non-resonant production, an effective coupling strength above 0.2 is excluded at 95% confidence level for the top quark and an invisible spin-1 state with mass between 0 and 657 GeV.« less

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

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.; Apresyan, A.; /Purdue U. /Waseda U.

    2010-06-01

    We present a measurement of the electric charge of the top quark using p{bar p} collisions corresponding to an integrated luminosity of 2.7 fb{sup -1} at the CDF II detector. We reconstruct t{bar t} events in the lepton+jets final state and use kinematic information to determine which b-jet is associated with the leptonically- or hadronically-decaying t-quark. Soft lepton taggers are used to determine the b-jet flavor. Along with the charge of the W boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with 2.4 {+-} 0.8 expected background events, 29 are reconstructed as tt with the standard model +2/3 charge, whereas 16 are reconstructed as t{bar t} with an exotic -4/3 charge. This is consistent with the standard model and excludes the exotic scenario at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.

  17. 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.

    2011-12-01

    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.

  18. Search for anomalous single top quark production in association with a photon in pp collisions at ?(s) = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-13

    We found the results of a search for flavor changing neutral currents (FCNC) through single top quark production in association with a photon is presented. The study is based on proton-proton collisions at a center-of-mass energy of 8 TeV using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb-1. The search for t? events where t ? Wb andW ? ?n is conducted in final states with a muon, a photon, at least one hadronic jet with at most one being consistent with originating from a bottom quark, and missing transverse momentum. Furthermore, there was no evidence of single top quark production in association with a photon through a FCNC is observed. Upper limits at the 95% confidence level are set on the tug and tcg anomalous couplings and translated into upper limits on the branching fraction of the FCNC top quark decays: B(t ? u?) < 1.3 x 10-4 and B(t ?c?) < 1.7 x 10-3. Upper limits are also set on the cross section of associated t? production in a restricted phase-space region. These are the most stringent limits currently available.

  19. 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.

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

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-08-01

    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.

  1. 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.

    2009-08-01

    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.

  2. 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.

    2008-09-01

    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.

  3. 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

    2014-11-27

    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

  4. 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

    2014-11-27

    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.

  5. Search for Standard Model Production of Four Top Quarks in the Lepton + Jets Channel in pp Collisions at $$\\sqrt{s}$$ = 8 TeV

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

    Khachatryan, Vardan

    2014-09-27

    Our 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 fb-1 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 σSMt¯tt¯t≈1fb. A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. We determined that the data are consistent with expectations of the SM, and an upper limit of 32 fb is set atmore » 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.« less

  6. Search for Standard Model Production of Four Top Quarks in the Lepton + Jets Channel in pp Collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-09-27

    Our 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 fb-1 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 σSMt¯tt¯t≈1fb. A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. We determined that 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.

  7. Searching for New Physics with Top Quarks and Upgrade to the Muon Spectrometer at ATLAS

    SciTech Connect (OSTI)

    Schwarz, Thomas Andrew

    2015-06-29

    Over the funding period of this award, my research has focused on searching for new physics with top quarks and in the Higgs sector. The highly energetic top quark events at the LHC are an excellent venue to search for new physics, as well as make standard model measurements. Further, the recent discovery of the Higgs boson motivates searching for new physics that could be associated with it. This one-year award has facilitated the beginning of my research program, which has resulted in four publications, several conference talks, and multiple leadership positions within physics groups. Additionally, we are contributing to ATLAS upgrades and operations. As part of the Phase I upgrade, I have taken on the responsibility of the design, prototyping, and quality control of a signal packet router for the trigger electronics of the New Small Wheel. This is a critical component of the upgrade, as the router is the main switchboard for all trigger signals to track finding processors. I am also leading the Phase II upgrade of the readout electronics of the muon spectrometer, and have been selected as the USATLAS Level-2 manager of the Phase II upgrade of the muon spectrometer. The award has been critical in these contributions to the experiment.

  8. Searches for New Physics in Top Decays at D0

    SciTech Connect (OSTI)

    Pleier, Marc-Andre; /Brookhaven

    2011-08-01

    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}.

  9. 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

    2014-09-30

    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?, 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.

  10. Search for Violation of Lorentz Invariance in Top Quark Pair Production and Decay

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Aoki, M.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Berger, M. S.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; 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.; Buszello, C. P.; Camacho-Perez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; 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.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Garcia-Gonzalez, J. A.; Garcia-Guerra, G. A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J. -F.; Grohsjean, A.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; 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.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffre, M.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; 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.; Kiselevich, I.; Kohli, J. M.; Kostelecky, V. A.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, T.; Kuzmin, V. A.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; et al.

    2012-06-27

    Using data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to 5.3 fb{sup -1} of integrated luminosity, we search for violation of Lorentz invariance by examining the t{bar t} production cross section in lepton+jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the t{bar t} production cross section on sidereal time as the orientation of the detector changes with the rotation of the Earth. Within this framework, we measure components of the matrices (c{sub Q}){sub {mu}{nu}33} and (c{sub U}){sub {mu}{nu}33} containing coefficients used to parametrize violation of Lorentz invariance in the top quark sector. Within uncertainties, these coefficients are found to be consistent with zero.

  11. 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.

    2015-01-12

    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$_{R}$.

  12. 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.

    2015-01-12

    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

  13. 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, Vardan

    2015-01-12

    We presented a measurement of the W boson helicity, 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. We also found that the data sample corresponds to an integratedmore » 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.« less

  14. Measurement of single top quark production in the tau+jets channnel using boosted decision trees at D0

    SciTech Connect (OSTI)

    Liu, Zhiyi; ,

    2009-12-01

    The top quark is the heaviest known matter particle and plays an important role in the Standard Model of particle physics. At hadron colliders, it is possible to produce single top quarks via the weak interaction. This allows a direct measurement of the CKM matrix element V{sub tb} and serves as a window to new physics. The first direct measurement of single top quark production with a tau lepton in the final state (the tau+jets channel) is presented in this thesis. The measurement uses 4.8 fb{sup -1} of Tevatron Run II data in p{bar p} collisions at {radical}s = 1.96 TeV acquired by the D0 experiment. After selecting a data sample and building a background model, the data and background model are in good agreement. A multivariate technique, boosted decision trees, is employed in discriminating the small single top quark signal from a large background. The expected sensitivity of the tau+jets channel in the Standard Model is 1.8 standard deviations. Using a Bayesian statistical approach, an upper limit on the cross section of single top quark production in the tau+jets channel is measured as 7.3 pb at 95% confidence level, and the cross section is measured as 3.4{sub -1.8}{sup +2.0} pb. The result of the single top quark production in the tau+jets channel is also combined with those in the electron+jets and muon+jets channels. The expected sensitivity of the electron, muon and tau combined analysis is 4.7 standard deviations, to be compared to 4.5 standard deviations in electron and muon alone. The measured cross section in the three combined final states is {sigma}(p{bar p} {yields} tb + X,tqb + X) = 3.84{sub -0.83}{sup +0.89} pb. A lower limit on |V{sub tb}| is also measured in the three combined final states to be larger than 0.85 at 95% confidence level. These results are consistent with Standard Model expectations.

  15. Model-independent measurement of t-channel single top quark production in p(p)over-bar collisions at,root s=1.96 TeV

    SciTech Connect (OSTI)

    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.; Arov, M.; Askew, A.; Asman, B.; Atramentov, O.; Avila, C.; BackusMayes, J.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, R.; 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.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; 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-Perez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cochran, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; 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.; Eller, P.; 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.; Focke, C.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; 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.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; 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.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffre, M.; Jamin, D.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; 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.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, 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.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; et al.

    2011-11-17

    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.

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

    SciTech Connect (OSTI)

    Aaltonen, T.; Abazov, V.M.; Abbott, B.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Alvarez Gonzalez, B.; Alverson, G.; /Northeastern U. /INFN, Padua

    2012-02-01

    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 2.7-5.4 fb{sup -1} of p{bar p} collisions collected during Run II of the Fermilab Tevatron Collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f{sub 0}) and right-handed (f{sub +}) helicities, we find f{sub 0} = 0.722 {+-} 0.081 [{+-} 0.062 (stat.) {+-} 0.052 (syst.)] and f{sub +} = -0.033 {+-} 0.046 [{+-} 0.034 (stat.) {+-} 0.031 (syst.)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f{sub 0} = 0.682 {+-} 0.057 [{+-} 0.035 (stat.) {+-} 0.046 (syst.)] and f{sub +} = ?0.015 {+-} 0.035 [{+-} 0.018 (stat.) {+-} 0.030 (syst.)]. The results are consistent with standard model expectations.

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

    SciTech Connect (OSTI)

    Cao Junjie; Heng Zhaoxia; Yang Jinmin; Wu Lei

    2009-03-01

    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. Search for Pair Production of Scalar Top Quarks Decaying to a tau Lepton and a b Quark in ppbar Collisions at sqrt{s}=1.96 TeV

    SciTech Connect (OSTI)

    Brigliadori, L.; Zheng, Y.; Zucchelli, S.; /Taiwan, Inst. Phys. /Bologna U. /Argonne /Barcelona, IFAE /Baylor U., Math. Dept. /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara /Cantabria U., Santander /Carnegie Mellon U.

    2008-02-01

    We present the results of a search for pair production of scalar top quarks ({tilde t}{sub 1}) in an R-parity violating supersymmetric scenario using 322 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. We assume each {tilde t}{sub 1} decays into a {tau} lepton and a b quark with a branching ratio {beta}, and that the final state contains 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 our final selection criteria, consistent with the expectation from standard model processes. We present upper limits on the cross section times branching ratio squared {sigma}({tilde t}{sub 1}{bar {tilde t}}{sub 1}) x {beta}{sup 2} as a function of the stop mass m({tilde t}{sub 1}). Assuming {beta} = 1, we set a 95% confidence level limit m({tilde t}{sub 1}) > 153 GeV=c{sup 2} obtained using a next-to-leading order cross section. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark decaying into a {tau} lepton and a b quark.

  19. Top quark pair production cross section in the lepton+jets channel using b-tagging at D0

    SciTech Connect (OSTI)

    Yoo, H.D.; /Brown U.

    2008-05-01

    The top quark pair production cross section measurement in the lepton+jets channel with b-tagging algorithm is described. About 900 pb{sup -1} data collected by the D0 detector at the Fermilab Tevatron are used for this analysis. In this thesis, event selection, background estimation, and cross section calculation are discussed in detail. In addition, calibration of the Luminosity Monitor readout electronics and a new b-tagging algorithm, the SLTNN tagger, are also discussed in this thesis.

  20. TOP AND HIGGS PHYSICS AT THE HADRON COLLIDERS

    SciTech Connect (OSTI)

    Jabeen, Shabnam

    2013-10-20

    This review summarizes the recent results for top quark and Higgs boson measurements from experiments at Tevatron, a proton–antiproton collider at a center-of-mass energy of √ s =1 . 96 TeV, and the Large Hadron Collider, a proton–proton 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.

  1. Combination of searches for anomalous top quark couplings with 5.4 fb(-1) of p(p)over-bar collisions

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Aoki, M.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; 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.; Buszello, C. P.; Camacho-Perez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; 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.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Garcia-Gonzalez, J. A.; Garcia-Guerra, G. A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph; Grivaz, J-F; Grohsjean, A.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; 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.; Howley, I.; Hubacek, Z.; Hynek, V.; Lashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffe, M.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; 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.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, T.; Kuzmin, V. A.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; et al.

    2012-07-09

    We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in t{bar t} events. We set upper limits on anomalous tWb coupling form factors using data collected with the D0 detector at the Tevatron p{bar p} collider corresponding to an integrated luminosity of 5.4 fb{sup -1}.

  2. Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $\\bf V_{tb}$

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero

    2015-10-07

    In this study, we present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96TeV. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment. The t-channel cross section is measured to be ?t= 2.25-0.31+0.29 pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in ?s+t= 3.30-0.40+0.52 pb, without assuming the standard model value for the ratio ?s/?t. The resulting value of the magnitude of the top-to-bottom quark coupling is |Vtb|= 1.02-0.05+0.06, corresponding to |Vtb| > 0.92 at the 95%C.L.

  3. Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $$\\bf V_{tb}$$

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

    Aaltonen, Timo Antero; Helsinki Institute of Physics, Helsinki

    2015-10-07

    In this study, we present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment. The t-channel cross section is measured to be σt= 2.25-0.31+0.29 pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in σs+t= 3.30-0.40+0.52 pb, without assuming the standard model value for the ratio σs/σt. The resulting valuemore » of the magnitude of the top-to-bottom quark coupling is |Vtb|= 1.02-0.05+0.06, corresponding to |Vtb| > 0.92 at the 95% C.L.« less

  4. Search for a dark matter candidate produced in association with a single top quark in $p\\bar{p}$ collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anza, F.; Apollinari, G.; Appel, J.A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2012-02-01

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb{sup -1} of Tevatron p{bar p} collisions at {radical}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 p{bar p} {yields} 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 0 - 150 GeV/c{sup 2}.

  5. Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-06-17

    A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s√=8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb-1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.

  6. 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

    2005-01-01

    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.

  7. Publisher's Note: New mechanism for the top-bottom mass hierarchy...

    Office of Scientific and Technical Information (OSTI)

    New mechanism for the top-bottom mass hierarchy Phys. Rev. D 70, 055006 (2004) Citation Details In-Document Search Title: Publisher's Note: New mechanism for the top-bottom mass ...

  8. Spectral probabilities of top-down tandem mass spectra

    SciTech Connect (OSTI)

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

    2014-01-24

    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.

  9. First Measurement of the Cross Section for Top-Quark Pair Production in Proton-Proton Collisions at $\\sqrt{s}=7$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2011-01-01

    The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy sqrt(s)= 7 TeV has been performed using 3.1 {\\pm} 0.3 inverse pb of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 {\\pm} 1.0 events expected from background. The measured cross section is 194 {\\pm} 72 (stat.) {\\pm} 24 (syst.) {\\pm} 21 (lumi.) pb, consistent with next-to-leading order predictions.

  10. 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

    2011-07-11

    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

  11. Top quark flavor-changing neutral-current decays and productions at LHC in the littlest Higgs model with T parity

    SciTech Connect (OSTI)

    Han Xiaofang; Wang Lei; Yang Jinmin

    2009-07-01

    In the littlest Higgs model with T-parity (LHT) the newly introduced mirror quarks have flavor-changing couplings with the standard model (SM) quarks and may enhance the flavor-changing neutral-current (FCNC) top-quark interactions which are extremely suppressed in the SM. In this work we perform a comprehensive study for the contributions of these mirror fermions to various top-quark FCNC decays and productions at the LHC, which includes the decays t{yields}cV (V=g, {gamma}, Z), t{yields}cgg and the productions proceeding through the parton processes cg{yields}t, gg{yields}tc, cg{yields}tg, cg{yields}t{gamma} and cg{yields}tZ. We find that although these FCNC processes can be greatly enhanced by the LHT contributions, they are hardly accessible at the LHC. Therefore, the LHT model may not cause the FCNC problem in the top-quark sector if the top-quark property is proved to be SM-like at the LHC.

  12. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp̄ Collisions at √s=1.96 TeV

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

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anzá, F.; Apollinari, G.; Appel, J. A.; et al

    2012-05-15

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb⁻¹ 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 pp̄→t+D as a function of the massmore » of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0–150 GeV/c².« less

  13. Search for the associated production of a Higgs boson with a single top quark in proton-proton collisions at ?(s) = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-09-29

    Our paper presents the search for the production of a Higgs boson in association with a single top quark, using data collected in proton-proton collisions at a centerof-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb-1. The search exploits a variety of Higgs boson decay modes resulting in final states with photons, bottom quarks, and multiple charged leptons, including tau leptons, and employs a variety of multivariate techniques to maximize sensitivity to the signal. Furthermore, our analysis is optimized for the opposite sign of the Yukawa coupling to that in the standard model and corresponding to a large enhancement of the signal cross section. In the absence of an excess of candidate signal events over the background predictions, 95% confidence level observed (expected) upper limits on anomalous tHq production are set, ranging between 600 (450) fb and 1000 (700) fb depending on the assumed diphoton branching fraction of the Higgs boson. This is the first time that results on anomalous tHq production have been reported.

  14. Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $$\\sqrt{s}$$ = 8 TeV

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

    Khachatryan, V.

    2015-06-17

    A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s√=8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb-1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and topmore » quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.« less

  15. 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

    2012-04-01

    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.

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

    SciTech Connect (OSTI)

    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.

    2011-02-18

    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.)].

  17. Search for flavour-changing neutral current top quark decays t ? Hq in pp collisions at ?s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; 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.; Affolder, A. A.; Agatonovic-Jovin, T.; Agricola, J.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; kesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; lvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; 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.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; 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.; 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.; Augsten, K.; Aurousseau, M.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; 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.; Basalaev, A.; Bassalat, A.; Basye, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, 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, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; 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.; Biedermann, D.; Biesuz, N. V.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biondi, S.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J. -B.; Blanco, J. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Bogaerts, J. A.; Bogavac, D.; Bogdanchikov, A. G.; 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.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutle, S. K.; 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.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Bruschi, M.; Bruscino, N.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.

    2015-12-10

    A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at ?s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb-1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt? WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t ? Hc and t ? Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H ? ?? and H ? WW*, ?? decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t ? Hc and t ? Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |? tcH | and |? tuH | couplings are 0.13 (0.10) and 0.13 (0.10) respectively. As a result, these are the most restrictive direct bounds on tqH interactions measured so far.

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

    SciTech Connect (OSTI)

    Collaboration, CDF; Aaltonen, T.

    2007-12-01

    We present the first measurement of {sigma}(gG {yields} t{bar t})/{sigma}(p{bar p} {yields} t{bar t}). We use 0.96 fb{sup -1} of {radical}s = 1.96 TeV p{bar p} collision data recorded with the CDF II detector at Fermilab. We identify the candidate t{bar t} events with a high-energy charged lepton, a neutrino candidate, and four or more jets with at least one identified as originating from a b quark. Using charged particles with low transverse momentum in t{bar t} events, we find {sigma}(gg {yields} t{bar t})/{sigma}(p{bar p} {yields} t{bar t}) = 0.07 {+-} 0.14(stat) {+-} 0.07(syst), in agreement with the standard model NLO prediction of 0.15 {+-} 0.05.

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

    SciTech Connect (OSTI)

    Aaltonen, T.

    2011-07-11

    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-bar 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.

  20. Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector

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

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

    2015-12-10

    A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb-1. Data are analysedmore » in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯→ WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW*, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λ tcH | and |λ tuH | couplings are 0.13 (0.10) and 0.13 (0.10) respectively. As a result, these are the most restrictive direct bounds on tqH interactions measured so far.« less

  1. Publisher's Note: New mechanism for the top-bottom mass hierarchy [Phys.

    Office of Scientific and Technical Information (OSTI)

    Rev. D 70, 055006 (2004)] (Journal Article) | SciTech Connect New mechanism for the top-bottom mass hierarchy [Phys. Rev. D 70, 055006 (2004)] Citation Details In-Document Search Title: Publisher's Note: New mechanism for the top-bottom mass hierarchy [Phys. Rev. D 70, 055006 (2004)] No abstract prepared. Authors: Hashimoto, Michio ; Kanemura, Shinya Publication Date: 2004-12-01 OSTI Identifier: 20698190 Resource Type: Journal Article Resource Relation: Journal Name: Physical Review. D,

  2. Search for flavour-changing neutral current top-quark decays to qZ in pp collision data collected with the ATLAS detector at √s = 8 TeV

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

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

    2016-01-08

    A search for the flavour-changing neutral-current decay t → qZ is presented. Data collected by the ATLAS detector during 2012 from proton–proton collisions at the Large Hadron Collider at a centre-of-mass energy of √s = 8 TeV, corresponding to an integrated luminosity of 20.3 fb–1 , are analysed. Top-quark pair-production events with one top quark decaying through the t → qZ ( q=u,c ) channel and the other through the dominant Standard Model mode t → bW are considered as signal. Only the decays of the Z boson to charged leptons and leptonic W boson decays are used. Furthermore, nomore » evidence for a signal is found and an observed (expected) upper limit on the t → qZ branching ratio of 7×10–4 ( 8×10–4) is set at the 95 % confidence level« less

  3. Erratum to: Constraining couplings of top quarks to the Z boson in $$ t\\overline{t} $$ + Z production at the LHC

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

    Röntsch, Raoul; Schulze, Markus

    2015-09-21

    We study top quark pair production in association with a Z boson at the Large Hadron Collider (LHC) and investigate the prospects of measuring the couplings of top quarks to the Z boson. To date these couplings have not been constrained in direct measurements. Such a determination will be possible for the first time at the LHC. Our calculation improves previous coupling studies through the inclusion of next-to-leading order (NLO) QCD corrections in production and decays of all unstable particles. We treat top quarks in the narrow-width approximation and retain all NLO spin correlations. To determine the sensitivity of amore » coupling measurement we perform a binned log-likelihood ratio test based on normalization and shape information of the angle between the leptons from the Z boson decay. The obtained limits account for statistical uncertainties as well as leading theoretical systematics from residual scale dependence and parton distribution functions. We use current CMS data to place the first direct constraints on the ttbZ couplings. We also consider the upcoming high-energy LHC run and find that with 300 inverse fb of data at an energy of 13 TeV the vector and axial ttbZ couplings can be constrained at the 95% confidence level to C_V=0.24^{+0.39}_{-0.85} and C_A=-0.60^{+0.14}_{-0.18}, where the central values are the Standard Model predictions. This is a reduction of uncertainties by 25% and 42%, respectively, compared to an analysis based on leading-order predictions. We also translate these results into limits on dimension-six operators contributing to the ttbZ interactions beyond the Standard Model.« less

  4. Measurement of the production cross-section of a single top quark in association with a W boson at 8 TeV with the ATLAS experiment

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

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

    2016-01-11

    The cross-section for the production of a single top quark in association with a W boson in proton-proton collisions at √s = 8 is measured. The dataset corresponds to an integrated luminosity of 20.3 fb-1, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central b-jet are selected. The Wt signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of Wt events is observed with a significance of 7.7σ. The cross-section is extracted in amore » profile likelihood fit to the classifier output distributions. The Wt cross-section, inclusive of decay modes, is measured to be 23.0±1.3(stat.)-3.5+3.2(syst.)±1.1(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element |Vtb| of 1.01 ± 0.10 and a lower limit of 0.80 at the 95% confidence level. Furthermore, the cross-section for the production of a top quark and a W boson is also measured in a fiducial acceptance requiring two leptons with p T > 25 GeV and |η| < 2.5, one jet with pT > 20 GeV and |η| < 2.5, and ETmiss >20 GeV, including both Wt and top-quark pair events as signal. The measured value of the fiducial cross-section is 0.85 ± 0.01(stat.) -0.07 +0.06 (syst.)±0.03(lumi.) pb.« less

  5. Erratum to: Constraining couplings of top quarks to the Z boson in $ t\\overline{t} $ + Z production at the LHC

    SciTech Connect (OSTI)

    Röntsch, Raoul; Schulze, Markus

    2015-09-21

    We study top quark pair production in association with a Z boson at the Large Hadron Collider (LHC) and investigate the prospects of measuring the couplings of top quarks to the Z boson. To date these couplings have not been constrained in direct measurements. Such a determination will be possible for the first time at the LHC. Our calculation improves previous coupling studies through the inclusion of next-to-leading order (NLO) QCD corrections in production and decays of all unstable particles. We treat top quarks in the narrow-width approximation and retain all NLO spin correlations. To determine the sensitivity of a coupling measurement we perform a binned log-likelihood ratio test based on normalization and shape information of the angle between the leptons from the Z boson decay. The obtained limits account for statistical uncertainties as well as leading theoretical systematics from residual scale dependence and parton distribution functions. We use current CMS data to place the first direct constraints on the ttbZ couplings. We also consider the upcoming high-energy LHC run and find that with 300 inverse fb of data at an energy of 13 TeV the vector and axial ttbZ couplings can be constrained at the 95% confidence level to C_V=0.24^{+0.39}_{-0.85} and C_A=-0.60^{+0.14}_{-0.18}, where the central values are the Standard Model predictions. This is a reduction of uncertainties by 25% and 42%, respectively, compared to an analysis based on leading-order predictions. We also translate these results into limits on dimension-six operators contributing to the ttbZ interactions beyond the Standard Model.

  6. Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: The vector current contributions

    SciTech Connect (OSTI)

    Gao, Jun; Zhu, Hua Xing

    2014-12-17

    We report on a calculation of the vector current contributions to the electroweak production of top quark pairs in e+e annihilation at next-to-next-to-leading order in quantum chromodynamics. Our setup is fully differential and can be used to calculate any infrared-safe observable. The real emission contributions are handled by a next-to-next-to-leading order generalization of the phase-space slicing method. As a result, we demonstrate the power of our technique by considering its application to various inclusive and exclusive observables.

  7. 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.

    2011-04-01

    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.

  8. Measurement of the top quark pair production cross section in proton-proton collisions at $\\sqrt{s}=13$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-10-18

    The top quark pair production cross section is measured for the first time in proton-proton collisions at ?s= 13 TeV by theCMS experiment at the CERN LHC, using data corresponding to an integrated luminosity of 42 pb-1. The measurement is performed by analyzing events with at least one electron and one muon of opposite charge, and at least two jets. We then measured the cross section and found that was 769 60 (stat) 55 (syst) 92 (lumi) pb, in agreement with the expectation from the standard model.

  9. Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp-bar; Collisions at √s = 1.96 TeV

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

    Aaltonen, T.

    2011-07-11

    We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t→H±b → W±(*)a10b, and subsequently decaying into τ+τ-. Using a data sample corresponding to an integrated luminosity of 2.7 fb-1 collected by the CDF II detector in pp-bar 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→H±b formore » various masses of H± and a10.« less

  10. Precision measurement of the top quark mass in the lepton + jets...

    Office of Scientific and Technical Information (OSTI)

    This measurement uses a total of 4.3 fbsup -1 of integrated luminosity, requiring events ... TEVATRON; INTERMEDIATE BOSONS; LEPTONS; LUMINOSITY; MATRIX ELEMENTS; NEURAL NETWORKS; ...

  11. Measurement of the W boson helicity in top quark decays using 5.4 fb⁻¹ of pp̄ 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

    2011-02-18

    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⁻¹ of collisions recorded using the D0 detector at the Fermilab Tevatron pp̄ collider. We measure the fractions of longitudinal and right-handed W bosons to be f₀=0.669±0.102[±0.078(stat.)±0.065(syst.)] and f₊=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 f₀ fixed to the value from the standard model yields f₊=0.010±0.037[±0.022(stat.)±0.030(syst.)].

  12. Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb¯ in pp collisions at √s = 8 TeV with the ATLAS detector

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

    Aad, G.

    2015-07-29

    In this study, a search for the Standard Model Higgs boson produced in association with a top-quark pair, tt¯H, is presented. The analysis uses 20.3 fb–1 of pp collision data at √s=8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H→bb¯ 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 dominatedmore » by tt¯+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 tt¯+bb¯ 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 section is obtained at 95 % confidence level. The ratio of the measured tt¯H signal cross section to the Standard Model expectation is found to be μ=1.5±1.1 assuming a Higgs boson mass of 125GeV.« less

  13. Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb¯ in pp collisions at √s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2015-07-29

    In this study, a search for the Standard Model Higgs boson produced in association with a top-quark pair, tt¯H, is presented. The analysis uses 20.3 fb–1 of pp collision data at √s=8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H→bb¯ 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 tt¯+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 tt¯+bb¯ 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 section is obtained at 95 % confidence level. The ratio of the measured tt¯H signal cross section to the Standard Model expectation is found to be μ=1.5±1.1 assuming a Higgs boson mass of 125GeV.

  14. 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

    2014-09-17

    The measurement of a cross section for the production of top quarkantiquark pairs (tt) in association with a vector boson V (W or Z) in proton-proton collisions at ?s=8 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 ?) channels: a same-sign dilepton analysis targeting ttW events, and trilepton and four-lepton analyses designed for ttZ events. In the same-sign dilepton channel, the ttW cross section is measured as ?ttW=170+90-80(stat)70(syst)fb, corresponding to a significance ofmore1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ttZ cross section, ?ttZ=200+80-70(stat)+40-30(syst)fb-1, is obtained with a significance of 3.1 standard deviations. Finally, the measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ttV process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.less

  15. Measurements of single top quark production cross sections and |Vtb| in pp̄ 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

    2011-12-05

    We present measurements of production cross sections of single top quarks in pp̄ 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 Σ(pp̄ → tb + X, tqb + X) = 3.43-0.74+0.73 pb and use it to extract the CKM matrix element 0.79

  16. The relation between the fundamental scale controlling high-energy interactions of quarks and the proton mass

    SciTech Connect (OSTI)

    Deur, Alexandre; Brodsky, Stanley J.; de Teramond, Guy F.

    2015-04-06

    Quantum Chromodynamics (QCD) provides a fundamental description of the physics binding quarks into protons, neutrons, and other hadrons. QCD is well understood at short distances where perturbative calculations are feasible. Establishing an explicit relation between this regime and the large-distance physics of quark confinement has been a long-sought goal. A major challenge is to relate the parameter Λs, which controls the predictions of perturbative QCD (pQCD) at short distances, to the masses of hadrons. Here we show how new theoretical insights into QCD's behavior at large and small distances lead to an analytical relation between hadronic masses and Λs. The resulting prediction, Λs = 0.341 ± 0.024 GeV agrees well with the experimental value 0.339 ± 0.016 GeV. Conversely, the experimental value of Λs can be used to predict the masses of hadrons, a task which had so far only been accomplished through intensive numerical lattice calculations, requiring several phenomenological input parameters.

  17. 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

    2014-09-17

    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

  18. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-09-17

    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.

  19. Cold quark matter in compact stars

    SciTech Connect (OSTI)

    Franzon, B.; Fogaca, D. A.; Navarra, F. S.; Horvath, J. E.

    2013-03-25

    We used an equation of state for the cold quark matter to the study of properties of quark stars. We also discuss the absolute stability of quark matter and compute the mass-radius relation for self-bound stars.

  20. 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.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-03-01

    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}.

  1. Search for the production of single vector-like and excited quarks in the Wt final state in pp collisions at √s = 8 TeV with the ATLAS detector

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

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

    2016-02-17

    A search for vector-like quarks and excited quarks in events containing a top quark and a W boson in the final state is reported here. The search is based on 20.3 fb-1 of proton-proton collision data taken at the LHC at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector. Events with one or two leptons, and one, two or three jets are selected with the additional requirement that at least one jet contains a b-quark. Single-lepton events are also required to contain at least one large-radius jet from the hadronic decay of a high-pT W boson ormore » a top quark. No significant excess over the expected background is observed and upper limits on the cross-section times branching ratio for different vector-like quark and excited-quark model masses are derived. As a result, for the excited-quark production and decay to Wt with unit couplings, quarks with masses below 1500 GeV are excluded and coupling-dependent limits are set.« less

  2. The physics of top, w and z from LHC, Tevatron and HERA

    SciTech Connect (OSTI)

    Shabalina, Elizaveta; /Gottingen U.

    2010-12-01

    We summarize recent experimental results in electroweak and top quark physics presented at the conference. This overview covers new measurements of the properties of top quark and W and Z bosons from the LHC, Tevatron and HERA.

  3. Determination of the Z` Mass and Couplings Below Threshold at the NLC

    SciTech Connect (OSTI)

    Rizzo, Thomas G.

    1996-12-31

    We investigate the capability of the NLC to indirectly determine both the mass as well as the couplings to leptons and b-quarks of a new neutral gauge boson below direct production threshold. By using data collected at several different values of the collide center of mass energy, we demonstrate how this can be done in an anonymous and model- independent manner. The procedure can be easily extended to the top and charm quark couplings.

  4. Measurement of the t-channel single-top-quark production cross section and of the $$\\mid V_{tb} \\mid$$ CKM matrix element in pp collisions at $$\\sqrt{s}$$= 8 TeV

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

    Khachatryan, Vardan

    2014-06-16

    Our 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-1 recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop (t¯), in final states with a muon or an electron. The measured inclusive t-channel cross section is σ t-ch. = 83.6 ± 2.3 (stat.) ± 7.4 (syst.) pb. The single t and t¯ cross sections are measured to be σ t-ch.(t) =more » 53.8 ± 1.5 (stat.) ± 4.4 (syst.) pb and σ t-ch. (t¯) = 27.6 ± 1.3 (stat.) ± 3.7 (syst.) pb, respectively. The measured ratio of cross sections is R t-ch. = σ t-ch.(t)/σ t-ch. (t¯) = 1.95 ± 0.10 (stat.) ± 0.19 (syst.), in agreement with the standard model prediction. Finally, the modulus of the Cabibbo-Kobayashi-Maskawa matrix element V tb is extracted and, in combination with a previous CMS result at √s = 7 TeV, a value |V tb| = 0.998 ± 0.038 (exp.) ± 0.016 (theo.) is obtained.« less

  5. 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.; et al.,

    2014-06-01

    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.

  6. Measurement of top anti-top cross section in proton - anti-proton collider at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Mal, Prolay Kumar

    2005-04-01

    Discovery of the top quark in 1995 at the Fermilab Tevatron collider concluded a long search following the 1977 discovery of bottom (b) quark [1] and represents another triumph of the Standard Model (SM) of elementary particles. Top quark is one of the fundamental fermions in the Standard Model of electroweak interactions and is the weak-isospin partner of the bottom quark. A precise measurement of top pair production cross-section would be a test of Quantum Chromodynamics (QCD) prediction. Presently, Tevatron is the world's highest energy collider where protons (p) and anti-protons ({anti p}) collide at a centre of mass energy (ps) of 1.96 TeV. At Tevatron top (t) and anti-top ({anti t}) quarks are predominantly pair produced through strong interactions--quark annihilation ({approx_equal} 85%) and gluon fusion ({approx_equal} 15%). Due to the large mass of top quark, t or {anti t} decays ({approx} 10{sup -25} sec) before hadronization and in SM framework, it decays to a W boson and a b quark with {approx} 100% branching ratio (BR). The subsequent decay of W boson determines the major signatures of t{anti t} decay. If both W bosons (coming from t and {anti t} decays) decay into leptons (viz., ev{sub e}, {mu}{nu}{sub {mu}} or {tau}{nu}{sub {tau}}) the corresponding t{bar t} decay is called dileptonic decay. Of all dileptonic decay modes of t{bar t}, the t{bar t} {yields} WWb{anti b} {yields} ev{sub e}{mu}{nu}{sub {mu}}b{anti b} (e{mu} channel) decay mode has the smallest background contamination from Z{sup 0} production or Drell-Yan process; simultaneously, it has the highest BR ({approx} 3.16%) [2] amongst all dileptonic decay modes of t{bar t}. During Run I (1992-1996) of Tevatron, three e{mu} candidate events were detected by D0 experiment, out of 80 candidate events (inclusive of all decay modes of t{bar t}). Due to the rarity of the t{bar t} events, the measured cross-section has large uncertainty in its value (viz., 5.69 {+-} 1.21(stat) {+-} 1.04(sys) pb {at} {radical}s = 1.8 TeV measured by D0 [3]). This analysis presents a cross section measurement in e{mu} channel utilizing {approx} 228 pb{sup -1} of data collected by D0 experiment during Tevatron Run II (between June 2002 and April 2004).

  7. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV

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

    Khachatryan, Vardan

    2014-09-17

    The measurement of a cross section for the production of top quark–antiquark pairs (tt¯) in association with a vector boson V (W or Z) in proton-proton collisions at √s=8 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 μ) channels: a same-sign dilepton analysis targeting tt¯W events, and trilepton and four-lepton analyses designed for tt¯Z events. In the same-sign dilepton channel, the tt¯W cross section is measured as σtt¯W=170+90-80(stat)±70(syst)fb, corresponding to a significance ofmore » 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the tt¯Z cross section, σtt¯Z=200+80-70(stat)+40-30(syst)fb-1, is obtained with a significance of 3.1 standard deviations. Finally, the measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive tt¯V process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.« less

  8. QUARK-NOVAE IN LOW-MASS X-RAY BINARIES. II. APPLICATION TO G87-7 AND TO GRB 110328A

    SciTech Connect (OSTI)

    Ouyed, Rachid; Staff, Jan; Jaikumar, Prashanth

    2011-12-20

    We propose a simple model explaining two outstanding astrophysical problems related to compact objects: (1) that of stars such as G87-7 (alias EG 50) that constitute a class of relatively low-mass white dwarfs (WDs) which nevertheless fall away from the C/O composition and (2) that of GRB 110328A/Swift J164449.3+57345 which showed spectacularly long-lived strong X-ray flaring, posing a challenge to standard gamma-ray burst models. We argue that both these observations may have an explanation within the unified framework of a quark-nova (QN) occurring in a low-mass X-ray binary (LMXB; neutron star (NS)-WD). For LMXBs, where the binary separation is sufficiently tight, ejecta from the exploding NS triggers nuclear burning in the WD on impact, possibly leading to Fe-rich composition compact WDs with mass 0.43 M{sub Sun} < M{sub WD} < 0.72 M{sub Sun }, reminiscent of G87-7. Our results rely on the assumption, which ultimately needs to be tested by hydrodynamic and nucleosynthesis simulations, that under certain circumstances the WD can avoid the thermonuclear runaway. For heavier WDs (i.e., M{sub WD} > 0.72 M{sub Sun }) experiencing the QN shock, degeneracy will not be lifted when carbon burning begins, and a sub-Chandrasekhar Type Ia supernova may result in our model. Under slightly different conditions and for pure He WDs (i.e., M{sub WD} < 0.43 M{sub Sun }), the WD is ablated and its ashes raining down on the quark star (QS) leads to accretion-driven X-ray luminosity with energetics and duration reminiscent of GRB 110328A. We predict additional flaring activity toward the end of the accretion phase if the QS turns into a black hole.

  9. 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.

    2010-05-01

    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.

  10. 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.; Erö, J.; Fabjan, C.; Friedl, M.; et al

    2011-12-29

    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⁻¹, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for themore » decay T→tZ, a T quark with a mass less than 475 GeV/c² is excluded at the 95% confidence level.« less

  11. 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.; Erö, J.; Fabjan, C.; Friedl, M.; et al

    2011-12-29

    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⁻¹, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for themore »decay T→tZ, a T quark with a mass less than 475 GeV/c² is excluded at the 95% confidence level.« less

  12. Press Pass - Press Release - Single Top

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

    DZero finds evidence of rare single top quark; Observation marks a step closer to finding Higgs boson Batavia, Ill.--Scientists of the DZero collaboration at the Department of...

  13. Fermilab - Top Quark Press Release (Historical)

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

    Laboratory

  14. Press Pass - Press Release - Single top quark

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

    of Orr, Minn., discusses the impact NOvA will have on his city. The proprietors of the Ash Trail Lodge in Ash River, Minn., discuss the impact NOvA will have on their business...

  15. Probing top-Z dipole moments at the LHC and ILC

    SciTech Connect (OSTI)

    Röntsch, Raoul; Schulze, Markus

    2015-08-11

    We investigate the weak electric and magnetic dipole moments of top quark-Z boson interactions at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). Their vanishingly small magnitude in the Standard Model makes these couplings ideal for probing New Physics interactions and for exploring the role of top quarks in electroweak symmetry breaking. In our analysis, we consider the production of two top quarks in association with a Z boson at the LHC, and top quark pairs mediated by neutral gauge bosons at the ILC. These processes yield direct sensitivity to top quark-Z boson interactions and complement indirect constraints from electroweak precision data. Our computation is accurate to next-to-leading order in QCD, we include the full decay chain of top quarks and the Z boson, and account for theoretical uncertainties in our constraints. Furthermore, we find that LHC experiments will soon be able to probe weak dipole moments for the first time.

  16. The Top...is it There? A Survey of the CDF and D0 Experiments

    DOE R&D Accomplishments [OSTI]

    Tollestrup, A. V.

    1994-12-01

    This paper describes: (1) features that the top quark must have if it exists, and how those features are inferred from various experiments; (2) how top quarks may be produced; (3) what must be accomplished to directly establish that the top quark has been produced in an experiment. Relevant features of the CDF and D0 detectors are described, as are methods useful in a top-quark search for identifying and detecting various kinds of particles. The author reviews data found by both CDF and D0, and discusses differences between the detectors and the data found with each.

  17. Erratum: Chiral transition and mesonic excitations for quarks...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Erratum: Chiral transition and mesonic excitations for quarks with thermal masses Phys. Rev. D 75, 011901 (2007) Citation Details ...

  18. Search for the production of an excited bottom quark decaying to tW in proton-proton collisions at $\\sqrt{s} =$ 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-09-29

    Our search is presented for a singly produced excited bottom quark (b*) decaying to a top quark and a W boson in the all-hadronic, lepton+jets, and dilepton final states in proton-proton collisions at √s = 8 TeV recorded by the CMS experiment at the CERN LHC. Data corresponding to an integrated luminosity of 19.7 fb-1 are used. No significant excess of events is observed with respect to standard model expectations. We set limits at 95% confidence on the product of the b* quark production cross section and its branching fraction to tW. Furthermore, the cross section limits are interpreted for scenarios including left-handed, right-handed, and vector-like couplings of the b* quark and are presented in the two-dimensional coupling plane based on the production and decay coupling constants. The masses of the left-handed, right-handed, and vectorlike b* quark states are excluded at 95% confidence below 1390, 1430, and 1530 GeV, respectively, for benchmark couplings. This analysis gives the most stringent limits on the mass of the b* quark to date.

  19. Top decays in extended models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O. G.; Cabral-Rosetti, L. G.

    2009-04-20

    Top quark decays are interesting as a mean to test the Standard Model (SM) predictions. The Cabbibo-Kobayashi-Maskawa (CKM)-suppressed process t{yields}cWW, and the rare decays t{yields}cZ, t{yields}H{sup 0}+c, and t{yields}c{gamma} an excellent window to probe the predictions of theories beyond the SM. We evaluate the flavor changing neutral currents (FCNC) decay t{yields}H{sup 0}+c in the context of Alternative Left-Right symmetric Models (ALRM) with extra isosinglet heavy fermions; the FCNC decays may place at tree level and are only supressed by the mixing between ordinary top and charm quarks. We also comment on the decay process t{yields}c+{gamma}, which involves radiative corrections.

  20. Current trends in non-accelerator particle physics: 1, Neutrino mass and oscillation. 2, High energy neutrino astrophysics. 3, Detection of dark matter. 4, Search for strange quark matter. 5, Magnetic monopole searches

    SciTech Connect (OSTI)

    He, Yudong |

    1995-07-01

    This report is a compilation of papers reflecting current trends in non-accelerator particle physics, corresponding to talks that its author was invited to present at the Workshop on Tibet Cosmic Ray Experiment and Related Physics Topics held in Beijing, China, April 4--13, 1995. The papers are entitled `Neutrino Mass and Oscillation`, `High Energy Neutrino Astrophysics`, `Detection of Dark Matter`, `Search for Strange Quark Matter`, and `Magnetic Monopole Searches`. The report is introduced by a survey of the field and a brief description of each of the author`s papers.

  1. Quark Forces from Hadronic Spectroscopy (Journal Article) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Quark Forces from Hadronic Spectroscopy Citation Details In-Document Search Title: Quark Forces from Hadronic Spectroscopy We consider the implications of the most general two-body quark-quark interaction Hamiltonian for the spin-flavor structure of the negative parity L=1 excited baryons. Assuming the most general two-body quark interaction Hamiltonian, we derive two correlations among the masses and mixing angles of these states, which constrain the mixing angles, and can be used to test for

  2. Quarkyonic Matter and Quark Number Scaling of Elliptic Flow

    SciTech Connect (OSTI)

    Csernai, L. P.; Zschocke, S.; Horvat, Sz.; Cheng Yun; Mishustin, I. N.

    2011-05-23

    The constituent quark number scaling of elliptic flow is studied in a non-equilibrium hadronization and freeze-out model with rapid dynamical transition from ideal, deconfined and chirally symmetric Quark Gluon Plasma, to final non-interacting hadrons. In this transition a Bag model of constituent quarks is considered, where the quarks gain constituent quark mass while the background Bag-field breaks up and vanishes. The constituent quarks then recombine into simplified hadron states, while chemical, thermal and flow equilibrium break down one after the other. In this scenario the resulting temperatures and flow velocities of baryons and mesons are different. Using a simplified few source model of the elliptic flow, we are able to reproduce the constituent quark number scaling, with assumptions on the details of the non-equilibrium processes.

  3. Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

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

    Aad, G.

    2015-02-24

    This article reports on a search for dark matter pair production in association with bottom or top quarks in 20.3 fb–1 of pp collisions collected at √s=8 TeV by the ATLAS detector at the LHC. Events with large missing transverse momentum are selected when produced in association with high-momentum jets of which one or more are identified as jets containing b-quarks. Final states with top quarks are selected by requiring a high jet multiplicity and in some cases a single lepton. The data are found to be consistent with the Standard Model expectations and limits are set on the massmore » scale of effective field theories that describe scalar and tensor interactions between dark matter and Standard Model particles. Limits on the dark-matter–nucleon cross-section for spin-independent and spin-dependent interactions are also provided. These limits are particularly strong for low-mass dark matter. Using a simplified model, constraints are set on the mass of dark matter and of a colored mediator suitable to explain a possible signal of annihilating dark matter.« less

  4. Heavy-quark physics in quantum chromodynamics

    SciTech Connect (OSTI)

    Brodsky, S.J.

    1991-04-01

    Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as {Upsilon} {yields} p{bar p} and B {yields} {pi}{pi}, and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x{sub F} and give anomalous contributions to the quark structure functions of ordinary hadrons at large x{sub bj}. I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/{psi} and {Upsilon} production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x{sub F}, and the coalescence of heavy quarks with co-moving spectators at low x{sub F}.

  5. Exploration of below threshold Z{sup {prime}} mass and coupling determinations at the NLC

    SciTech Connect (OSTI)

    Rizzo, T.G.

    1997-05-01

    We examine of the capability of the Next Linear Collider to determine the mass as well as the couplings to leptons and b quarks of a new neutral gauge boson Z{sup {prime}} below direct production threshold. By using simulated data collected at several different values of {radical}(s), we demonstrate how this can be done in a model-independent manner via an anonymous case approach. The importance of beam polarization to the success of this program is discussed. The procedure is shown to be easily extended to the case of top and charm quark couplings. {copyright} {ital 1997} {ital The American Physical Society}

  6. Search for top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in √s = 8 TeV pp collisions with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2014-11-21

    The results of a search for top squark (stop) pair production in final states with one isolated lepton, jets, and missing transverse momentum are reported. The analysis is performed with proton-proton collision data at √s = 8 TeV collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20 fb–1. The lightest supersymmetric particle (LSP) is taken to be the lightest neutralino which only interacts weakly and is assumed to be stable. The stop decay modes considered are those to a top quark and the LSP as well as to a bottom quark and the lightest chargino, where the chargino decays to the LSP by emitting a W boson. A wide range of scenarios with different mass splittings between the stop, the lightest neutralino and the lightest chargino are considered, including cases where the W bosons or the top quarks are off-shell. Decay modes involving the heavier charginos and neutralinos are addressed using a set of phenomenological models of supersymmetry. No significant excess over the Standard Model prediction is observed. A stop with a mass between 210 and 640 GeV decaying directly to a top quark and a massless LSP is excluded at 95% confidence level, and in models where the mass of the lightest chargino is twice that of the LSP, stops are excluded at 95% confidence level up to a mass of 500 GeV for an LSP mass in the range of 100 to 150 GeV. As a result, stringent exclusion limits are derived for all other stop decay modes considered, and model-independent upper limits are set on the visible cross-section for processes beyond the Standard Model.

  7. Search for top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in √s = 8 TeV pp collisions with the ATLAS detector

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

    Aad, G.

    2014-11-21

    The results of a search for top squark (stop) pair production in final states with one isolated lepton, jets, and missing transverse momentum are reported. The analysis is performed with proton-proton collision data at √s = 8 TeV collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20 fb–1. The lightest supersymmetric particle (LSP) is taken to be the lightest neutralino which only interacts weakly and is assumed to be stable. The stop decay modes considered are those to a top quark and the LSP as well as to a bottom quark andmore » the lightest chargino, where the chargino decays to the LSP by emitting a W boson. A wide range of scenarios with different mass splittings between the stop, the lightest neutralino and the lightest chargino are considered, including cases where the W bosons or the top quarks are off-shell. Decay modes involving the heavier charginos and neutralinos are addressed using a set of phenomenological models of supersymmetry. No significant excess over the Standard Model prediction is observed. A stop with a mass between 210 and 640 GeV decaying directly to a top quark and a massless LSP is excluded at 95% confidence level, and in models where the mass of the lightest chargino is twice that of the LSP, stops are excluded at 95% confidence level up to a mass of 500 GeV for an LSP mass in the range of 100 to 150 GeV. As a result, stringent exclusion limits are derived for all other stop decay modes considered, and model-independent upper limits are set on the visible cross-section for processes beyond the Standard Model.« less

  8. Erratum: Chiral transition and mesonic excitations for quarks with thermal

    Office of Scientific and Technical Information (OSTI)

    masses [Phys. Rev. D 75, 011901 (2007)] (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Erratum: Chiral transition and mesonic excitations for quarks with thermal masses [Phys. Rev. D 75, 011901 (2007)] Citation Details In-Document Search Title: Erratum: Chiral transition and mesonic excitations for quarks with thermal masses [Phys. Rev. D 75, 011901 (2007)] No abstract prepared. Authors: Hidaka, Yoshimasa ; Kitazawa, Masakiyo Publication Date: 2007-05-01

  9. Quark matter and meson properties in a Nonlocal SU(3) chiral quark model at finite temperature

    SciTech Connect (OSTI)

    Gomez Dumm, D.; Contrera, G. A.

    2012-06-15

    We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with a background color field. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles, and decay constants.

  10. Search for vector-like charge 2/3 T quarks in proton-proton collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-09-15

    Our search for fermionic top quark partners T of charge 2/3 is presented. The search is carried out in proton-proton collisions corresponding to an integrated luminosity of 19.7 fb-1 collected at a center-of-mass energy of √s = 8 TeV with the CMS detector at the LHC. The T quarks are assumed to be produced strongly in pairs and can decay into tH, tZ, and bW. The search is performed in five exclusive channels: a singlelepton channel, a multilepton channel, two all-hadronic channels optimized either for the bW or the tH decay, and one channel in which the Higgs boson decays into two photons. The results are found to be compatible with the standard model expectations in all the investigated final states. Finally, a statistical combination of these results is performed and lower limits on the T quark mass are set. Depending on the branching fractions, lower mass limits between 720 and 920 GeV at 95% confidence level are found. These are among the strongest limits on vector-like T quarks obtained to date.

  11. Quarkonium in a weakly-coupled quark-gluon plasma

    SciTech Connect (OSTI)

    Vairo, Antonio

    2010-12-22

    We report about a recent calculation of the heavy quarkonium mass and decay width in a quark-gluon plasma, whose temperature T and screening mass m{sub D} satisfy the hierarchy m{alpha}{sub s}>>T>>m{alpha}{sub s}{sup 2}>>m{sub D}, m being the heavy-quark mass, up to order m{alpha}{sub s}{sup 5}. The calculation may be relevant to understand the behavior of the {Upsilon}(1S) in a quark-gluon plasma at present-day colliders.

  12. Meson properties in a nonlocal SU(3) chiral quark model at finite temperature

    SciTech Connect (OSTI)

    Contrera, G. A.; Gomez Dumm, D.; Scoccola, N. N.

    2010-11-12

    Finite temperature meson properties are studied in the context of a nonlocal SU(3) quark model which includes flavor mixing and the coupling of quarks to the Polyakov loop (PL). We analyze the behavior of scalar and pseudoscalar meson masses and mixing angles, as well as quark-meson couplings and pseudoscalar meson decay constants.

  13. Electroweak matching conditions for top pair production at threshold

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Electroweak matching conditions for top pair production at threshold Citation Details In-Document Search Title: Electroweak matching conditions for top pair production at threshold We determine the real parts of electroweak matching conditions relevant for top quark pair production close to threshold in e{sup +}e{sup -} annihilation at next-to-next-to-leading logarithmic (NNLL) order. Numerically the corrections are comparable to the NNLL QCD corrections.

  14. Exotic quarks in Twin Higgs models

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

    Cheng, Hsin -Chia; Jung, Sunghoon; Salvioni, Ennio; Tsai, Yuhsin

    2016-03-14

    The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ~ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of themore » model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. As a result, depending on the details of the twin sector, the exotic quarks may be probed up to ~ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.« less

  15. Measurement of the charge asymmetry in top-quark pair production in the lepton-plus-jets final state in pp collision data at √s = 8 TeV with the ATLAS detector

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

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

    2016-02-19

    This paper reports inclusive and differential measurements of the tt¯ charge asymmetry AC in 20.3 fb–1 of √s = 8 TeV pp collisions recorded by the ATLAS experiment at the Large Hadron Collider at CERN. Three differential measurements are performed as a function of the invariant mass, transverse momentum and longitudinal boost of the tt¯ system. The tt¯ pairs are selected in the single-lepton channels (e or μ) with at least four jets, and a likelihood fit is used to reconstruct the tt¯ event kinematics. A Bayesian unfolding procedure is performed to infer the asymmetry at parton level from themore » observed data distribution. The inclusive tt¯ charge asymmetry is measured to be AC = 0.009 ± 0.005) (stat. + syst.). As a result, the inclusive and differential measurements are compatible with the values predicted by the Standard Model.« less

  16. Evidence for electroweak top quark production in proton-antiproton...

    Office of Scientific and Technical Information (OSTI)

    Identifier: 924529 Report Number(s): FERMILAB-THESIS-2007-55 TRN: US0802910 DOE Contract Number: AC02-07CH11359 Resource Type: ThesisDissertation Research Org: Fermi National...

  17. Top Quark Forward-Backward Asymmetry in e + e - Annihilation...

    Office of Scientific and Technical Information (OSTI)

    GrantContract Number: AC02-06CH11357; AC02-76SF00515 Type: Publisher's Accepted Manuscript Journal Name: Physical Review Letters Additional Journal Information: Journal Volume: ...

  18. Evidence for single top quark production at D0 (Conference) ...

    Office of Scientific and Technical Information (OSTI)

    Bibtex Format Close 0 pages in this document matching the terms "" Search For Terms: Enter terms in the toolbar above to search the full text of this document for pages...

  19. Top Quark Anomalous Couplings at the International Linear Collider...

    Office of Scientific and Technical Information (OSTI)

    the tbar tZ and Wtbar b couplings. Authors: Devetak, Erik ; Nomerotski, Andrei ; Oxford U. ; Peskin, Michael ; SLAC Publication Date: 2011-08-15 OSTI Identifier: 1022544...

  20. Evidence for single top quark production at D0 (Conference) ...

    Office of Scientific and Technical Information (OSTI)

    de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy, 10-17 Mar 2007 Research Org: Fermi National Accelerator Laboratory (FNAL), Batavia, IL Sponsoring...

  1. Probing top-Z dipole moments at the LHC and ILC

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

    Röntsch, Raoul; Schulze, Markus

    2015-08-11

    We investigate the weak electric and magnetic dipole moments of top quark-Z boson interactions at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). Their vanishingly small magnitude in the Standard Model makes these couplings ideal for probing New Physics interactions and for exploring the role of top quarks in electroweak symmetry breaking. In our analysis, we consider the production of two top quarks in association with a Z boson at the LHC, and top quark pairs mediated by neutral gauge bosons at the ILC. These processes yield direct sensitivity to top quark-Z boson interactions and complement indirectmore » constraints from electroweak precision data. Our computation is accurate to next-to-leading order in QCD, we include the full decay chain of top quarks and the Z boson, and account for theoretical uncertainties in our constraints. Furthermore, we find that LHC experiments will soon be able to probe weak dipole moments for the first time.« less

  2. Higgs mass from compositeness at a multi-TeV scale

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

    Cheng, Hsin -Chia; Dobrescu, Bogdan A.; Gu, Jiayin

    2014-08-18

    Within composite Higgs models based on the top seesaw mechanism, we show that the Higgs field can arise as the pseudo Nambu-Goldstone boson of the broken U(3)more » $$_{L}$$ chiral symmetry associated with a vector-like quark and the t-b doublet. As a result, the lightest CP-even neutral state of the composite scalar sector is lighter than the top quark, and can be identified as the newly discovered Higgs boson. As a result, constraints on weak-isospin violation push the chiral symmetry breaking scale above a few TeV, implying that other composite scalars are probably too heavy to be probed at the LHC, but may be within reach at a future hadron collider with center-of-mass energy of about 100 TeV.« less

  3. Baryon Spectroscopy and the Constituent Quark Model

    SciTech Connect (OSTI)

    A.W. Thomas; R.D. Young

    2005-07-26

    We explore further the idea that the lattice QCD data for hadron properties in the region m[^2][_pi] > 0.2GeV^2 can be described by the constituent quark model. This leads to a natural explanation of the fact that nucleon excited states are generally stable for pion masses greater than their physical excitation energies. Finally, we apply these same ideas to the problem of how pentaquarks might behave in lattice QCD, with interesting conclusions.

  4. Search for direct top squark pair production in final states with two tau leptons in pp collisions at √s = 8  TeV with the ATLAS detector

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

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

    2016-02-16

    A search for direct pair production of the supersymmetric partner of the top quark, decaying via a scalar tau to a nearly massless gravitino, has been performed using 20 fb-1 of proton–proton collision data at √s = 8 TeV . The data were collected by the ATLAS experiment at the LHC in 2012. Top squark candidates are searched for in events with either two hadronically decaying tau leptons, one hadronically decaying tau and one light lepton, or two light leptons. No significant excess over the Standard Model expectation is found. Exclusion limits at 95% confidence level are set as amore » function of the top squark and scalar tau masses. As a result, depending on the scalar tau mass, ranging from the 87 GeV LEP limit to the top squark mass, lower limits between 490 and 650 GeV are placed on the top squark mass within the model considered.« less

  5. S-wave QQqq state in the constituent quark model

    SciTech Connect (OSTI)

    Yang Youchang; Deng Chengrong; Ping Jialun; Goldman, T.

    2009-12-01

    Many proposals have been put forward to explore four-quark states QQqq (Q=s, c, b; q=u, d) by experiment, so a systematic study of QQqq spectrum with different constituent quark models by a high precision, few-body method, the Gaussian expression method, is useful. Three quark models: the Bhaduri, Cohler, Nogami quark model, the chiral quark model (ChQM), and the quark delocalization color screening model are all employed for a systematic calculation of the S-wave QQqq spectrum with different color structures, using the Gaussian expression method. The results show that only the bbqq state with (I,J)=(0,1) is bound in different color structures within the different quark models. The binding energy varies from several MeV for a di-meson structure to over 100 MeV for a diquark-antidiquark structure. For the ccqq system, the state with (I,J)=(0,1) is bound in a di-meson structure, and also bound in a diquark-antidiquark structure if pseudoscalar meson exchanges are accounted for. All are weakly bound states. The mixture of diquark-antidiquark and molecular structures is discussed in the framework of quark models for the first time; ccqq with (I,J)=(0,1) is below the threshold in addition to bbqq in both the ChQM and the Bhaduri, Cohler, Nogami quark model. In the same channel, ssqq is also a possible bound state with mass around 1.4 GeV in ChQM.

  6. Exotic decays of heavy B quarks

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

    Fox, Patrick J.; Tucker-Smith, David

    2016-01-08

    Heavy vector-like quarks of charge –1/3, B, have been searched for at the LHC through the decays B → bZ, bh, tW. In models where the B quark also carries charge under a new gauge group, new decay channels may dominate. We focus on the case where the B is charged under a U(1)' and describe simple models where the dominant decay mode is B → bZ' → b(bb¯¯). With the inclusion of dark matter such models can explain the excess of gamma rays from the Galactic center. We develop a search strategy for this decay chain and estimate thatmore » with integrated luminosity of 300 fb–1 the LHC will have the potential to discover both the B and the Z' for B quarks with mass below ~ 1.6 TeV, for a broad range of Z' masses. Furthermore, a high-luminosity run can extend this reach to 2 TeV.« less

  7. Aspects of the strongly interacting matter phase diagram within non-local quark models

    SciTech Connect (OSTI)

    Pagura, V.; Dumm, D. G.; Scoccola, N. N.

    2013-03-25

    We study a nonlocal extension of the so-called Polyakov Nambu-Jona-Lasinio model at finite temperature and chemical potential, considering the impact of the presence of dynamical quarks on the scale parameter appearing in the Polyakov potential. Both real and imaginary chemical potentials are considered. The effect of varying the current quark mass is also investigated.

  8. Equation of state and heavy-quark free energy at finite temperature and density in two flavor lattice QCD with Wilson quark action

    SciTech Connect (OSTI)

    Ejiri, S.; Maezawa, Y.; Ukita, N.; Aoki, S.; Hatsuda, T.; Ishii, N.; Kanaya, K.; Umeda, T.

    2010-07-01

    We study the equation of state at finite temperature and density in two-flavor QCD with the renormalization group improved gluon action and the clover-improved Wilson quark action on a 16{sup 3}x4 lattice. Along the lines of constant physics at m{sub PS}/m{sub V}=0.65 and 0.80, we compute the second and forth derivatives of the grand canonical partition function with respect to the quark chemical potential {mu}{sub q}=({mu}{sub u}+{mu}{sub d})/2 and the isospin chemical potential {mu}{sub I}=({mu}{sub u}-{mu}{sub d})/2 at vanishing chemical potentials, and study the behaviors of thermodynamic quantities at finite {mu}{sub q} using these derivatives for the case {mu}{sub I}=0. In particular, we study density fluctuations at nonezero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to {mu}{sub q}. To suppress statistical fluctuations, we also examine new techniques applicable at low densities. We find a large enhancement in the fluctuation of the quark number when the density increased near the pseudocritical temperature, suggesting a critical point at finite {mu}{sub q} terminating the first order transition line between hadronic and quark-gluon-plasma phases. This result agrees with the previous results using staggered-type quark actions qualitatively. Furthermore, we study heavy-quark free energies and Debye screening masses at finite density by measuring the first and second derivatives of these quantities for various color channels of heavy quark-quark and quark-antiquark pairs. The results suggest that, to the leading order of {mu}{sub q}, the interaction between two quarks becomes stronger at finite densities, while that between quark and antiquark becomes weaker.

  9. Quark Gluon Plasma

    SciTech Connect (OSTI)

    Lincoln, Don

    2015-05-07

    Matter is malleable and can change its properties with temperature. This is most familiar when comparing ice, liquid water and steam, which are all different forms of the same thing. However beyond the usual states of matter, physicists can explore other states, both much colder and hotter. In this video, Fermilabs Dr. Don Lincoln explains the hottest known state of matter a state that is so hot that protons and neutrons from the center of atoms can literally melt. This form of matter is called a quark gluon plasma and it is an important research topic being pursued at the LHC.

  10. Top physics: measurement of the tt-bar production cross section in p anti-p collisions at s**(1/2) = 1.96 tev using lepton + jets events with secondary vertex b-tagging

    SciTech Connect (OSTI)

    Acosta, D.; The CDF Collaboration

    2005-04-07

    We present a measurement of the t{bar t} production cross section using events with one charged lepton and jets from p{bar p} collisions at a center-of-mass energy of 1.96TeV. In these events, heavy flavor quarks from top quark decay are identified with a secondary vertex tagging algorithm. From 162 pb{sup -1} of data collected by the Collider Detector at Fermilab, a total of 48 candidate events are selected, where 13.5 {+-} 1.8 events are expected from background contributions. We measure a t{bar t} production cross section of 5.6{sub -1.1}{sup _1.2}(stat.){sub -0.6}{sup +0.9}(syst.)pb.

  11. Geometric representation of fundamental particles' inertial mass

    SciTech Connect (OSTI)

    Schachter, L.; Spencer, James

    2015-07-22

    A geometric representation of the (N = 279) masses of quarks, leptons, hadrons and gauge bosons was introduced by employing a Riemann Sphere facilitating the interpretation of the N masses in terms of a single particle, the Masson, which might be in one of the N eigen-states. Geometrically, its mass is the radius of the Riemann Sphere. Dynamically, its derived mass is near the mass of the nucleon regardless of whether it is determined from all N particles of only the hadrons, the mesons or the baryons separately. Ignoring all the other properties of these particles, it is shown that the eigen-values, the polar representation ?? of the masses on the Sphere, satisfy the symmetry ?? + ?N+1-? = ? within less than 1% relative error. In addition, these pair correlations include the pairs ?? + ?top ? ? and ?gluon + ?H ? ? as well as pairing the weak gauge bosons with the three neutrinos.

  12. Mixings of four-quark components in light nonsinglet scalar mesons in QCD sum rules

    SciTech Connect (OSTI)

    Sugiyama, J.; Nakamura, T.; Nishikawa, T.; Oka, M.; Ishii, N.

    2007-12-01

    Mixings of four-quark components in the nonsinglet scalar mesons are studied in the QCD sum rules. We propose a formulation to evaluate the cross correlators of qq and qqqq operators and to define the mixings of different Fock states in the sum rule. It is applied to the nonsinglet scalar mesons, a{sub 0} and K{sub 0}*. It is found that the four-quark operators predict lower masses than the qq operators and that the four-quark states occupy about 70%-90% of the lowest mass states.

  13. Top Science of 2013

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

    RAPTOR telescope witnesses black hole birth science-innovationassetsimagesicon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research...

  14. Top Science of 2013

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

    Liquid-scanning technology boosts airport security science-innovationassetsimagesicon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research...

  15. Top NAICS Codes

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

    and Related Products Manufacturing for Measuring, Displaying, Top Ten NAICS Codes Dollar Value 511210 Software Publishers 334516 Analytical Laboratory Instrument Manufacturing...

  16. Top Science of 2013

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

    Roadrunner firsts pave way for greener, faster supercomputing science-innovationassetsimagesicon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and ...

  17. Physics at the 100 GeV mass scale: Proceedings

    SciTech Connect (OSTI)

    Brennan, E.C.

    1990-01-01

    This report contains the following papers: heavy quarks--experimental; the theory of heavy flavour production; precision experiments in electroweak interactions; theory of precision electroweak measurements; applications of QCD to hadron-hadron collisions; W{sup +}W{sup {minus}} interactions and the search for the Higgs Boson; electroweak symmetry breaking: Higgs/Whatever; electron-positron storage rings as heavy quark factories; prospects for next-generation e{sup +}e{sup {minus}} linear colliders; current prospects for hadron colliders; hadron colliders beyond the SSC; recent results on weak decays of charmed mesons from the Mark 3 experiment; recent CLEO results on bottom and charm; recent results on B-decays from ARGUE; a review of recent results on the hadron and photoproduction of charm; search for the top quark at UA1; recent results from the UA2 experiment at the CERN {bar p}p collider; selected preliminary results from CDF; new measurement of the phase difference {Phi}{sub 00} {minus} {Phi}{sub {plus minus}} in CP--violating K{sup 0} decays; a recent result on CP violation by E731 at Fermilab; rare kaon decay experiments; CP violation; inverse muon decay, neutrino dimuon production, and a search for neutral heavy leptons at the tevatron; first results from MACRO; a superstring theory underview; recent results from TRISTAN ; measurements of the Z boson resonance parameters at SLC; decays of the Z boson; and theory--weak neutral currents and the Z mass after the SLC.

  18. Exploiting Third Generation Quarks for New Physics Discoveries at the Energy Frontier

    SciTech Connect (OSTI)

    Ivanov, Andrew G.

    2013-10-15

    The K-State group's effort is top quark physics and searches for beyond-standard-model physics in t{anti #22;}t final states. The KSU team performed the most precise measurement of the t#22;{anti t} cross section in the lepton + jets channel, and for the first time excluded the fourth generation of the standard model in the perturbative regime.

  19. INTERACTING QUARK MATTER EQUATION OF STATE FOR COMPACT STARS

    SciTech Connect (OSTI)

    Fraga, Eduardo S.; Kurkela, Aleksi; Vuorinen, Aleksi

    2014-02-01

    Lattice quantum chromodynamics (QCD) studies of the thermodynamics of hot quark-gluon plasma demonstrate the importance of accounting for the interactions of quarks and gluons if one wants to investigate the phase structure of strongly interacting matter. Motivated by this observation and using state-of-the-art results from perturbative QCD, we construct a simple, effective equation of state (EOS) for cold quark matter that consistently incorporates the effects of interactions and furthermore includes a built-in estimate of the inherent systematic uncertainties. This goes beyond the MIT bag model description in a crucial way, yet leads to an EOS that is equally straightforward to use. We also demonstrate that, at moderate densities, our EOS can be made to smoothly connect to hadronic EOSs, with the two exhibiting very similar behavior near the matching region. The resulting hybrid stars are seen to have masses similar to those predicted by the purely nucleonic EOSs.

  20. The low and intermediate mass dilepton and photon results

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

    Ruan, Lijuan

    2014-10-18

    I summarize and discuss some of the experimental results on the low and intermediate mass dileptons and direct photons presented at Quark Matter 2014.

  1. A Search for scalar bottom quarks from gluino decays in anti-p 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. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2005-12-01

    We searched for scalar bottom quarks in 156 pb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV recorded by the CDF II experiment at the Tevatron. Scalar bottom quarks can be produced from gluino decays in R-parity conserving models of supersymmetry when the mass of the gluino exceeds that of the scalar bottom quark. Then, a scalar bottom quark can decay into a bottom quark and a neutralino. To search for this scenario, we investigated events with large missing transverse energy and at least three jets, two or more of which were identified as containing a secondary vertex from the hadronization of b quarks. We found four candidate events, where 2.6 {+-} 0.7 are expected from standard model processes, and placed 95% confidence level lower limits on gluino and scalar bottom quark masses of up to 280 and 240 GeV/c{sup 2} , respectively.

  2. The B*B? coupling using relativistic heavy quarks

    SciTech Connect (OSTI)

    Flynn, J. M.; Fritzsch, P.; Kawanai, T.; Lehner, C.; Samways, B.; Sachrajda, C. T.; Van de Water, R. S.; Witzel, O.

    2015-06-23

    We report on a calculation of the B*B? coupling in lattice QCD. The strong matrix element (B?|B*) is directly related to the leading order low-energy constant in heavy meson chiral perturbation theory (HM?PT) for B mesons. We carry out our calculation directly at the b-quark mass using a non-perturbatively tuned clover action that controls discretization effects of order |p?a| and (ma)n for all n. Our analysis is performed on RBC/UKQCD gauge configurations using domain-wall fermions and the Iwasaki gauge action at two lattice spacings of a1 = 1.729(25) GeV, a1 = 2.281 (28) GeV, and unitary pion masses down to 290 MeV. We achieve good statistical precision and control all systematic uncertainties, giving a final result for the HM?PT coupling gb = 0.56(3)stat(7)sys in the continuum and at the physical light-quark masses. Furthermore, this is the first calculation performed directly at the physical b-quark mass and lies in the region one would expect from carrying out an interpolation between previous results at the charm mass and at the static point.

  3. Flavor Physics in the Quark Sector

    SciTech Connect (OSTI)

    Antonelli, Mario; /Frascati; Asner, David Mark; /Carleton U.; Bauer, Daniel Adams; /Imperial Coll., London; Becher, Thomas G.; /Fermilab; Beneke, M.; /Aachen, Tech. Hochsch.; Bevan, Adrian John; /Queen Mary, U. of London; Blanke, Monika; /Munich, Tech. U. /Munich, Max Planck Inst.; Bloise, C.; /Frascati; Bona, Marcella; /CERN; Bondar, Alexander E.; /Novosibirsk, IYF; Bozzi, Concezio; /INFN, Ferrara; Brod, Joachim; /Karlsruhe U.; Buras, Andrzej J.; /Munich, Tech. U.; Cabibbo, N.; /INFN, Rome /Rome U.; Carbone, A.; /INFN, Bologna; Cavoto, Gianluca; /INFN, Rome; Cirigliano, Vincenzo; /Los Alamos; Ciuchini, Marco; /INFN, Rome; Coleman, Jonathon P.; /SLAC; Cronin-Hennessy, Daniel P.; /Minnesota U.; Dalseno, J.P.; /KEK, Tsukuba /Glasgow U. /Queen Mary, U. of London /Freiburg U. /Charles U. /Pisa U. /Vienna, OAW /Imperial Coll., London /Bergen U. /INFN, Rome /Rome U. /Munich, Tech. U. /INFN, Rome /Rome U. /Southampton U. /INFN, Rome /Nara Women's U. /Florida U. /INFN, Turin /Turin U. /Edinburgh U. /Warwick U. /INFN, Rome /Rome U. /Massachusetts U., Amherst /KEK, Tsukuba /Bern U. /CERN /Munich, Tech. U. /Mainz U., Inst. Phys. /Wayne State U. /Munich, Max Planck Inst. /CERN /Frascati /Brookhaven /Mainz U., Inst. Kernphys. /Munich, Tech. U. /Siegen U. /Imperial Coll., London /Victoria U. /KEK, Tsukuba /Fermilab /Washington U., St. Louis /Frascati /Warwick U. /Indian Inst. Tech., Madras /Melbourne U. /Princeton U. /Beijing, Inst. High Energy Phys. /INFN, Rome /INFN, Rome3 /Fermilab /SLAC /York U., Canada /Brookhaven /UC, Irvine /INFN, Rome /Rome U. /Valencia U., IFIC /INFN, Padua /Padua U. /Munich, Max Planck Inst. /Barcelona U. /Warwick U. /Tata Inst. /Frascati /Mainz U., Inst. Phys. /Vienna U. /KEK, Tsukuba /Orsay, LPT /Frascati /Munich, Tech. U. /Brookhaven /Bern U. /CERN /Mainz U., Inst. Phys. /Wayne State U. /Valencia U., IFIC /CERN /Kentucky U. /Oxford U. /Iowa State U. /Bristol U. /INFN, Rome /Rutherford /CERN /Orsay, LAL /Glasgow U. /INFN, Padua /Queen Mary, U. of London /Texas U. /LPHE, Lausanne /Fermilab /UC, Santa Cruz /Vienna, OAW /Cincinnati U. /Frascati /Orsay, LAL /Ohio State U. /Purdue U. /Novosibirsk, IYF /Frascati /INFN, Rome /Padua U. /INFN, Rome /Bern U. /Karlsruhe U. /Brookhaven /CERN /Paris U., VI-VII /Zurich, ETH /Pisa U. /Frascati /Oxford U. /Orsay, LAL /INFN, Rome2 /INFN, Rome /INFN, Rome3 /Princeton U. /Fermilab /Queen's U., Kingston /KEK, Tsukuba /Melbourne U. /Brookhaven /Indiana U. /INFN, Rome /Rome U. /Pisa U. /Mainz U., Inst. Phys. /Karlsruhe U. /Oxford U. /Cambridge U., DAMTP /Edinburgh U. /CERN

    2010-08-26

    In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report is the result of the work of the physicists attending the 5th CKM workshop, hosted by the University of Rome 'La Sapienza', September 9-13, 2008. It summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.

  4. Effects of the running of the QCD coupling on the energy loss in the quark-gluon plasma

    SciTech Connect (OSTI)

    Braun, Jens; Pirner, Hans-Juergen

    2007-03-01

    Finite temperature modifies the running of the QCD coupling {alpha}{sub s}(k,T) with resolution k. After calculating the thermal quark and gluon masses self-consistently, we determine the quark-quark and quark-gluon cross sections in the plasma based on the running coupling. We find that the running coupling enhances these cross sections by factors of two to four depending on the temperature. We also compute the energy loss (dE/dx) of a high-energy quark in the plasma as a function of temperature. Our study suggests that, beside t-channel processes, inverse Compton scattering is a relevant process for a quantitative understanding of the energy loss of an incident quark in a hot plasma.

  5. Kaluza-Klein masses of bulk fields with general boundary conditions in AdS{sub 5} space

    SciTech Connect (OSTI)

    Chang, Sanghyeon; Park, Seong Chan; Song, Jeonghyeon

    2005-05-15

    Recently bulk Randall-Sundrum theories with the gauge group SU(2){sub L}xSU(2){sub R}xU(1){sub B-L} have drawn a lot of interest as an alternative to the electroweak symmetry breaking mechanism. These models are in better agreement with electroweak precision data since custodial isospin symmetry on the IR-brane is protected by the extended bulk gauge symmetry. We comprehensively study, in the S{sup 1}/Z{sub 2}xZ{sub 2}{sup '} orbifold, the bulk gauge and fermion fields with the general boundary conditions as well as the bulk and localized mass terms. Master equations to determine the Kaluza-Klein (KK) mass spectra are derived without any approximation, which is an important basic step for various phenomenologies at high energy colliders. The correspondence between orbifold boundary conditions and localized mass terms is demonstrated not only in the gauge sector but also in the fermion sector. As the localized mass increases, the first KK fermion mass is shown to decrease while the first KK gauge boson mass is shown to increase. The degree of gauge coupling universality violation is computed to be small in most parameter space, and its correlation with the mass difference between the top quark and light quark KK mode is also studied.

  6. Matching the quark model to the 1/N{sub c} expansion (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Matching the quark model to the 1/N{sub c} expansion Citation Details In-Document Search Title: Matching the quark model to the 1/N{sub c} expansion We compute the coefficients of the effective mass operator of the 1/N{sub c} expansion for negative parity L = 1 excited baryons using the Isgur-Karl model in order to compare the general approach, where the coefficients are obtained by fitting to data, with a specific constituent quark model calculation. We discuss the physics

  7. Testing for three-body quark forces in L = 1 excited baryons (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Testing for three-body quark forces in L = 1 excited baryons Citation Details In-Document Search Title: Testing for three-body quark forces in L = 1 excited baryons We discuss the matching of the quark model to the effective mass operator of the 1/N{sub c} expansion using the permutation group S{sub N}. As an illustration of the general procedure we perform the matching of the Isgur-Karl model for the spectrum of the negative parity L = 1 excited baryons. Assuming

  8. Heavy hadrons in quark-gluon plasma

    SciTech Connect (OSTI)

    Narodetskii, I. M. Simonov, Yu. A.; Veselov, A. I.

    2011-03-15

    We use the nonperturbative quark-antiquark potential derived within the Field Correlator Method and the screened Coulomb potential to calculate binding energies and melting temperatures of heavy mesons and baryons in the deconfined phase of quark-gluon plasma.

  9. Top Ten Innovations of 2013

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

    Supercomputing Science Digests 70 Years of Innovations Top Ten Innovations of 2013 Energy Sustainability 50 Years of Space TOP INNOVATIONS OF 2013 Science and technology for...

  10. Heavy-quark production in ultrarelativistic heavy-ion collisions within a partonic transport model

    SciTech Connect (OSTI)

    Uphoff, Jan; Fochler, Oliver; Greiner, Carsten; Xu Zhe

    2010-10-15

    The production and space-time evolution of charm and bottom quarks in nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are investigated with the partonic transport model BAMPS (Boltzmann approach of multiparton scatterings). Heavy quarks, produced in primary hard parton scatterings during nucleon-nucleon collisions, are sampled using the Monte Carlo event generator pythia or the leading-order minijet model in conjunction with the Glauber model, revealing a strong sensitivity on the parton distribution functions, scales, and heavy-quark mass. In a comprehensive study exploring different charm masses, K factors, and possible initial gluon conditions, secondary production and the evolution of heavy quarks are examined within a fully dynamic BAMPS simulation for central heavy-ion collisions at RHIC and LHC. Although charm production in the quark-gluon plasma can be neglected at RHIC, it is significant at LHC but very sensitive to the initial conditions and the charm mass. Bottom production in the quark-gluon plasma, however, is negligible both at RHIC and LHC.

  11. B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

    SciTech Connect (OSTI)

    Christ, Norman H.; Flynn, Jonathan M.; Izubuchi, Taku; Kawanai, Taichi; Lehner, Christoph; Soni, Amarjit; Van de Water, Ruth S.; Witzel, Oliver

    2015-03-10

    We calculate the B-meson decay constants fB, fBs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ? 0.11, 0.086 fm with unitary pion masses as light as M? ? 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(?sa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain fB0 = 196.2(15.7) MeV, fB+ = 195.4(15.8) MeV, fBs = 235.4(12.2) MeV, fBs/fB0 = 1.193(59), and fBs/fB+ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.

  12. Quarks Pair Up in Protons (and Neutrons) | Jefferson Lab

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

    Graph of up quark/down quark contributions Researchers have published intriguing new observations for how the different kinds of quarks behave inside protons and neutrons. In the proton, the down quark contributes surprisingly little to electron-proton interaction. Also, the up quark contributes much less to electron-neutron interaction than one would expect if all three quarks behaved in similar ways. Quarks Pair Up in Protons (and Neutrons) Ordinarily, physicists generally think of protons and

  13. Top Performers Summer Fun

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

    Top Performers Summer Fun NSTec honors outstanding achievements. NNSA recognizes two of NFO's best. NSTEA offers hot vacation discounts. See pages 4-5. See page 3. Mitigation Fees Bring Opportunities for Tortoise Research Nevada National Security Site (NNSS) biologists have found a way to promote species research while keeping site-generated fees closer to home, thanks to a new agreement with the U.S. Fish and Wildlife Service (USFWS). In keeping with conservation laws, the USFWS charges NNSS

  14. Top Science of 2013

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

    Multipronged HIV vaccine shows promise in monkeys /science-innovation/_assets/images/icon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research facilities allow us to develop solutions to complex problems, and to support partners and collaborators, all with the goal of strengthening national security and making a safer world. lab worker Multipronged HIV vaccine shows promise in monkeys lab worker HIV constantly mutates into many different strains that

  15. Top Science of 2013

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

    Liquid-scanning technology boosts airport security /science-innovation/_assets/images/icon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research facilities allow us to develop solutions to complex problems, and to support partners and collaborators, all with the goal of strengthening national security and making a safer world. Liquid-scanning technology boosts airport security placeholder Uniquely combining Magnetic Resonance Imaging (MRI) and X-ray technology,

  16. Top Science of 2013

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

    RAPTOR telescope witnesses black hole birth /science-innovation/_assets/images/icon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research facilities allow us to develop solutions to complex problems, and to support partners and collaborators, all with the goal of strengthening national security and making a safer world. RAPTOR telescope witnesses black hole birth placeholder The first "thinking telescope" RAPTOR found the birth of big black holes,

  17. Top Science of 2013

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

    Space probes predict hazards to protect spacecraft /science-innovation/_assets/images/icon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research facilities allow us to develop solutions to complex problems, and to support partners and collaborators, all with the goal of strengthening national security and making a safer world. Space probes predict hazards to protect spacecraft placeholder Researchers think they've solved a 50-year-old space mystery about how

  18. PAGE Cover: Top Photo

    Energy Savers [EERE]

    PAGE Cover: Top Photo Energy Sciences Building. Elevation of the recently completed Energy Sciences Building (ESB) project at Argonne National Laboratory in Lemont, Illinois. The ESB was a capital line-item project funded by the Science Laboratories Infrastructure program at a total cost of $96 million and was completed on August 6, 2014. The ESB project provided 173,000 gross square feet of interdisciplinary research and collaborative space to accommodate a range of physical sciences research

  19. A new scoring function for top-down spectral deconvolution

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

    Kou, Qiang; Wu, Si; Liu, Xiaowen

    2014-12-18

    Background: Top-down mass spectrometry plays an important role in intact protein identification and characterization. Top-down mass spectra are more complex than bottom-up mass spectra because they often contain many isotopomer envelopes from highly charged ions, which may overlap with one another. As a result, spectral deconvolution, which converts a complex top-down mass spectrum into a monoisotopic mass list, is a key step in top-down spectral interpretation. Results: In this paper, we propose a new scoring function, L-score, for evaluating isotopomer envelopes. By combining L-score with MS-Deconv, a new software tool, MS-Deconv+, was developed for top-down spectral deconvolution. Experimental results showedmorethat MS-Deconv+ outperformed existing software tools in top-down spectral deconvolution. Conclusions: L-score shows high discriminative ability in identification of isotopomer envelopes. Using L-score, MS-Deconv+ reports many correct monoisotopic masses missed by other software tools, which are valuable for proteoform identification and characterization.less

  20. A new scoring function for top-down spectral deconvolution

    SciTech Connect (OSTI)

    Kou, Qiang [Indiana Univ.-Purdue Univ. Indianapolis, Indianapolis, IN (United States); Wu, Si [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Liu, Xiaowen [Indiana Univ. School of Medicine, Indianapolis, IN (United States)

    2014-12-18

    Background: Top-down mass spectrometry plays an important role in intact protein identification and characterization. Top-down mass spectra are more complex than bottom-up mass spectra because they often contain many isotopomer envelopes from highly charged ions, which may overlap with one another. As a result, spectral deconvolution, which converts a complex top-down mass spectrum into a monoisotopic mass list, is a key step in top-down spectral interpretation. Results: In this paper, we propose a new scoring function, L-score, for evaluating isotopomer envelopes. By combining L-score with MS-Deconv, a new software tool, MS-Deconv+, was developed for top-down spectral deconvolution. Experimental results showed that MS-Deconv+ outperformed existing software tools in top-down spectral deconvolution. Conclusions: L-score shows high discriminative ability in identification of isotopomer envelopes. Using L-score, MS-Deconv+ reports many correct monoisotopic masses missed by other software tools, which are valuable for proteoform identification and characterization.

  1. Cooking Up Hot Quark Soup

    DOE R&D Accomplishments [OSTI]

    Walsh, Karen McNulty

    2011-03-28

    Near-light-speed collisions of gold ions provide a recipe for in-depth explorations of matter and fundamental forces. The Relativistic Heavy Ion Collider (RHIC) has produced the most massive antimatter nucleus ever discovered—and the first containing an anti-strange quark. The presence of strange antimatter makes this antinucleus the first to be entered below the plane of the classic Periodic Table of Elements, marking a new frontier in physics.

  2. Thermal axion production in the primordial quark-gluon plasma

    SciTech Connect (OSTI)

    Graf, Peter; Steffen, Frank Daniel

    2011-04-01

    We calculate the rate for thermal production of axions via scattering of quarks and gluons in the primordial quark-gluon plasma. To obtain a finite result in a gauge-invariant way that is consistent to leading order in the strong gauge coupling, we use systematic field theoretical methods such as hard thermal loop resummation and the Braaten-Yuan prescription. The thermally produced yield, the decoupling temperature, and the density parameter are computed for axions with a mass below 10 meV. In this regime, with a Peccei-Quinn scale above 6x10{sup 8} GeV, the associated axion population can still be relativistic today and can coexist with the axion cold dark matter condensate.

  3. WIPP Receives Top Safety Award

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

    WIPP Receives Top Safety Award CARLSBAD, N.M., November 10, 2011 - The U.S. Department of Energy's (DOE) Waste Isolation Pilot Plant (WIPP) received top accolades from New...

  4. Review of meson spectroscopy: quark states and glueballs

    SciTech Connect (OSTI)

    Chanowitz, M.S.

    1981-11-01

    A group of three lectures on hadron spectroscopy are presented. Topics covered include: light L = 0 mesons, light L = 1 mesons, antiquark antiquark quark quark exotics, a catalogue of higher quark antiquark excitations, heavy quarkonium, and glueballs. (GHT)

  5. Fermi National Accelerator Laboratory June 2012

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

    recorded two distinct top-quark production mechanisms Explored a new mass range for the Higgs boson and constrained its mass through top-quark and W-boson mass measurements...

  6. Top-pair production and decay at NLO matched with parton showers

    SciTech Connect (OSTI)

    Campbell, John M.; Ellis, R. Keith; Nason, Paolo; Re, Emanuele

    2015-04-21

    We present a next-to-leading order (NLO) calculation of tt production in hadronic collisions interfaced to shower generators according to the POWHEG method. We start from an NLO result from previous work, obtained in the zero width limit, where radiative corrections to both production and decays are included. The POWHEG interface required an extension of the POWHEG BOX framework, in order to deal with radiation from the decay of resonances. This extension is fully general (i.e. it can be applied in principle to any process considered in the zero width limit), and is here applied for the first time. In order to perform a realistic simulation, we introduce finite width effects using different approximations, that we validated by comparing with published exact NLO results. We have interfaced our POWHEG code to the PYTHIA8 shower Monte Carlo generator. At this stage, we dealt with novel issues related to the treatment of resonances, especially with regard to the initial scale for the shower that needs to be set appropriately. This procedure affects, for example, the fragmentation function of the b quark, that we have studied with particular attention. We believe that the tool presented here improves over previous generators for all aspects that have to do with top decays, and especially for the study of issues related to top mass measurements that involve B hadrons or b jets. The work presented here also constitutes a first step towards a fully consistent matching of NLO calculations involving intermediate resonances decaying into coloured particles, with parton showers.

  7. Top-pair production and decay at NLO matched with parton showers

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

    Campbell, John M.; Ellis, R. Keith; Nason, Paolo; Re, Emanuele

    2015-04-21

    We present a next-to-leading order (NLO) calculation of tt production in hadronic collisions interfaced to shower generators according to the POWHEG method. We start from an NLO result from previous work, obtained in the zero width limit, where radiative corrections to both production and decays are included. The POWHEG interface required an extension of the POWHEG BOX framework, in order to deal with radiation from the decay of resonances. This extension is fully general (i.e. it can be applied in principle to any process considered in the zero width limit), and is here applied for the first time. In ordermoreto perform a realistic simulation, we introduce finite width effects using different approximations, that we validated by comparing with published exact NLO results. We have interfaced our POWHEG code to the PYTHIA8 shower Monte Carlo generator. At this stage, we dealt with novel issues related to the treatment of resonances, especially with regard to the initial scale for the shower that needs to be set appropriately. This procedure affects, for example, the fragmentation function of the b quark, that we have studied with particular attention. We believe that the tool presented here improves over previous generators for all aspects that have to do with top decays, and especially for the study of issues related to top mass measurements that involve B hadrons or b jets. The work presented here also constitutes a first step towards a fully consistent matching of NLO calculations involving intermediate resonances decaying into coloured particles, with parton showers.less

  8. Top-pair production and decay at NLO matched with parton showers

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

    Campbell, John M.; Ellis, R. Keith; Nason, Paolo; Re, Emanuele

    2015-04-21

    We present a next-to-leading order (NLO) calculation of tt¯ production in hadronic collisions interfaced to shower generators according to the POWHEG method. We start from an NLO result from previous work, obtained in the zero width limit, where radiative corrections to both production and decays are included. The POWHEG interface required an extension of the POWHEG BOX framework, in order to deal with radiation from the decay of resonances. This extension is fully general (i.e. it can be applied in principle to any process considered in the zero width limit), and is here applied for the first time. In ordermore » to perform a realistic simulation, we introduce finite width effects using different approximations, that we validated by comparing with published exact NLO results. We have interfaced our POWHEG code to the PYTHIA8 shower Monte Carlo generator. At this stage, we dealt with novel issues related to the treatment of resonances, especially with regard to the initial scale for the shower that needs to be set appropriately. This procedure affects, for example, the fragmentation function of the b quark, that we have studied with particular attention. We believe that the tool presented here improves over previous generators for all aspects that have to do with top decays, and especially for the study of issues related to top mass measurements that involve B hadrons or b jets. As a result, the work presented here also constitutes a first step towards a fully consistent matching of NLO calculations involving intermediate resonances decaying into coloured particles, with parton showers.« less

  9. Study of collisons of supersymmetric top Quark in the channel stop anti-stop -> e+- mu-+ sneutrino anti-sneutrino b anti-b with the experience of D0 at the Tevatron. Callibration of the electromagnetic calorimeter at D0.

    SciTech Connect (OSTI)

    Mendes, Aurelien; /Marseille U., Luminy

    2006-10-01

    Supersymmetry is one of the most natural extensions of the Standard Model. At low energy it may consist in the Minimal Supersymmetric Standard Model which is the framework chosen to perform the search of the stop with 350 pb{sup -1} of data collected by D0 during the RunIIa period of the TeVatron. They selected the events with an electron, a muon, missing transverse energy and non-isolated tracks, signature for the stop decay in 3-body ({bar t} {yields} bl{bar {nu}}). Since no significant excess of signal is seen, the results are interpreted in terms of limit on the stop production cross-sections, in such a way that they extend the existing exclusion region in the parameter space (m{sub {bar t}},m{sub {bar {nu}}}) up to stop masses of 168 (140) GeV for sneutrino masses of 50 (94) GeV. Finally because of the crucial role of the electromagnetic calorimeter, a fine calibration was performed using Z {yields} e{sup +}e{sup -} events, which improved significantly the energy resolution.

  10. Hadronic physics of q anti q light quark mesons, quark molecules and glueballs

    SciTech Connect (OSTI)

    Lindenbaum, S.J.

    1980-10-01

    A brief introduction reviews the development of QCD and defines quark molecules and glueballs. This review is concerned primarily with u, d, and s quarks, which provide practically all of the cross section connected with hadronic interactions. The following topics form the bulk of the paper: status of quark model classification for conventional u, d, s quark meson states; status of multiquark or quark molecule state predictions and experiments; glueballs and how to find them; and the OZI rule in decay and production and how glueballs might affect it. 17 figures, 1 table. (RWR)

  11. {rho}{phi}{phi} and {omega}{omega} vertex functions within a confined quark model

    SciTech Connect (OSTI)

    Mitchell, K.; Tandy, P.C.

    1993-10-01

    We report results of an investigation of the p{pi}{pi} vertex function calculated from a quark including the distributed {anti q}q nature of the mesons. The quark propaagator is an entire function of the form recently extracie in a model confining Schwinger-Dyson equation. The parameters of the prop gator are chosen to fit {pi}{pi} scattering lengths. The dependence of the p{pi}{pi} vertex upon the p momentum is extracted the coupling constant is extracted at the mass shell point and compared to a previous approximation based at zero momentum. The model is extended to study the G-parity violating {omega}{pi}{pi} vertex produced by an up-down current quark mass difference. This is a possible contributing`mechanism for p-{omega} mixing.

  12. Sea quark transverse momentum distributions and dynamical chiral...

    Office of Scientific and Technical Information (OSTI)

    Sea quark transverse momentum distributions and dynamical chiral symmetry breaking Citation Details In-Document Search Title: Sea quark transverse momentum distributions and...

  13. MARTINI event generator for heavy quarks: Initialization, parton...

    Office of Scientific and Technical Information (OSTI)

    MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Citation Details In-Document Search Title: MARTINI event generator for heavy quarks: ...

  14. Heavy Quarks, QCD, and Effective Field Theory Thomas Mehen 72...

    Office of Scientific and Technical Information (OSTI)

    Heavy Quarks, QCD, and Effective Field Theory Thomas Mehen 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS Heavy Quarks, Quarkonium,...

  15. Top-of-Rail lubricant

    SciTech Connect (OSTI)

    Alzoubi, M. F.; Fenske, G. R.; Erck, R. A.; Boparai, A. S.

    2000-07-14

    Analysis of the volatile and semivolatile fractions collected after use of the TOR lubricant indicated that other than contaminants in the collection laboratory, no compounds on the EPA's Target Compound Lists (Tables 2 and 5) were detected in these fractions. The data of these qualitative analyses, given in the various tables in the text, indicate only the relative amounts of the tentatively identified compounds. The authors recommend that quantitative analysis be performed on the volatile and semivolatile fractions to allow confirmation of the tentatively identified compounds and to obtain absolute amounts of the detected compounds. Additionally, the semivolatile fraction should be analyzed by liquid chromatography/mass spectrometry to identify compounds that are not chromatographable under the temperature program used for determination of semivolatile compounds. Introducing the top-of-rail (TOR) lubricant into the wheel/rail interface results in a reduction of almost 60% of lateral friction force over the forces encountered under dry conditions. This reveals good potential for energy savings, as well as wear reduction, for railroad companies. In TOR lubrication, an increase in the angle of attack and axle load results in increased lateral friction and rate of lubricant consumption. The most efficient TOR lubricant quantity to be used in the wheel/rail interface must be calculated precisely according to the number of cars, axle loads, train speed, and angle of attack.

  16. Top Science News of 2014

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

    Top Science News of 2014 Top Science News of 2014 Biosurveillance, secure computing, alternative energy, unique capabilities highlight the year December 22, 2014 Top Science News of 2014 Biosurveillance, secure computing, alternative energy, unique capabilities highlight the year. Contact Communications Office "The breadth of scientific expertise and range of disciplines necessary for supporting Los Alamos's national security mission can be seen when reflecting on some of the year's more

  17. Materials Technologies: Goals, Strategies, and Top Accomplishments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Materials Technologies: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) Materials Technologies: Goals, Strategies, and Top Accomplishments ...

  18. HUNTING THE QUARK GLUON PLASMA.

    SciTech Connect (OSTI)

    LUDLAM, T.; ARONSON, S.

    2005-04-11

    The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear matter at extremely high density and temperature--a medium in which the predictions of QCD can be tested, and new phenomena explored, under conditions where the relevant degrees of freedom, over nuclear volumes, are expected to be those of quarks and gluons, rather than of hadrons. This is the realm of the quark gluon plasma, the predicted state of matter whose existence and properties are now being explored by the RHIC experiments.

  19. Binding Energies and Melting Temperatures of Heavy Hadrons in Quark-Gluon Plasma

    SciTech Connect (OSTI)

    Narodetskii, I. M.; Simonov, Yu. A.; Veselov, A. I.

    2011-05-23

    We discuss the consequences of the suggestion that the non-perturbative quark-antiquark potential at T{>=}T{sub c}, where T{sub c} is a temperature of a deconfinement phase transition in QCD can be studied through the modification of the correlation functions, which define the quadratic field correlators of the nonperturbative vaccuum fields. We use the non-perturbative quark-antiquark potential derived within the Field Correlator Method and the screened Coulomb potential with T-dependent Debye mass to calculate J/{psi}, {Upsilon} and {Omega}{sub bbb} binding energies and melting temperatures in the deconfined phase of QCD.

  20. A mean field theory for the cold quark gluon plasma applied to stellar structure

    SciTech Connect (OSTI)

    Fogaca, D. A.; Navarra, F. S.; Franzon, B.; Horvath, J. E.

    2013-03-25

    An equation of state based on a mean-field approximation of QCD is used to describe the cold quark gluon plasma and also to study the structure of compact stars. We obtain stellar masses compatible with the pulsar PSR J1614-2230 that was determined to have a mass of (1.97 {+-} 0.04 M{sub Circled-Dot-Operator }), and the corresponding radius around 10-11 km.

  1. Quark-gluon correlation functions relevant to single transverse spin

    Office of Scientific and Technical Information (OSTI)

    asymmetries (Journal Article) | SciTech Connect Quark-gluon correlation functions relevant to single transverse spin asymmetries Citation Details In-Document Search Title: Quark-gluon correlation functions relevant to single transverse spin asymmetries We investigate the relative size of various twist-3 quark-gluon correlation functions relevant to single transverse spin asymmetries (SSAs) in a quark-diquark model of the nucleon. We calculate the quark-gluon correlation function T{sub

  2. Method for establishing a combustion zone in an in situ oil shale retort having a pocket at the top

    DOE Patents [OSTI]

    Cha, Chang Y. (1904 Glenmont Dr., Bakersfield, CA 93309)

    1980-01-01

    An in situ oil shale retort having a top boundary of unfragmented formation and containing a fragmented permeable mass has a pocket at the top, that is, an open space between a portion of the top of the fragmented mass and the top boundary of unfragmented formation. To establish a combustion zone across the fragmented mass, a combustion zone is established in a portion of the fragmented mass which is proximate to the top boundary. A retort inlet mixture comprising oxygen is introduced to the fragmented mass to propagate the combustion zone across an upper portion of the fragmented mass. Simultaneously, cool fluid is introduced to the pocket to prevent overheating and thermal sloughing of formation from the top boundary into the pocket.

  3. New Mechanism for Quark Energy Loss

    SciTech Connect (OSTI)

    Casalderrey-Solana, Jorge; Fernandez, Daniel; Mateos, David

    2010-04-30

    We show that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons. We demonstrate that this takes place in all strongly coupled, large-N{sub c} plasmas with a gravity dual. The energy loss is exactly calculable in these models despite being an O(1/N{sub c}) effect. We discuss implications for heavy-ion collision experiments.

  4. Λb→pl⁻ν¯l form factors from lattice QCD with static b quarks

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

    Detmold, William; Lin, C.-J. David; Meinel, Stefan; Wingate, Matthew

    2013-07-23

    We present a lattice QCD calculation of form factors for the decay Λb→pμ⁻ν¯μ, which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element |Vub| at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Λb→pμ⁻ν¯μ differential decay rate in the range 14more » GeV²≤q²≤q²max, and obtain the integral ∫q²max 14 GeV²[dΓ/dq²]dq²/|Vub|²=15.3±4.2 ps⁻¹. Combined with future experimental data, this will give a novel determination of |Vub| with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.« less

  5. Thermal charm production in a quark-gluon plasma in Pb-Pb collisions at {radical}(s{sub NN})=5.5 TeV

    SciTech Connect (OSTI)

    Zhang Benwei; Ko Cheming; Liu Wei

    2008-02-15

    Charm production from the quark-gluon plasma created in the midrapidity of central heavy ion collisions at the Large Hadron Collider (LHC) is studied in the next-to-leading order in QCD. Using a schematic longitudinally boost-invariant and transversally expanding fire-cylinder model, we find that charm production could be appreciably enhanced at LHC as a result of the high temperature that is expected to be reached in the produced quark-gluon plasma. Sensitivities of our results to the number of charm quark pairs produced from initial hard scattering, the initial thermalization time and temperature of the quark-gluon plasma, and the charm quark mass are also studied.

  6. Top-Quark Decay at Next-to-Next-to-Leading Order in QCD (Journal...

    Office of Scientific and Technical Information (OSTI)

    National Technical Information Service, Springfield, VA at www.ntis.gov. Authors: Gao, Jun ; Southern Methodist U. ; Li, Chong Sheng ; Peking U. Peking U., CAPT Peking U. ;...

  7. Electroweak production of top-quark pairs in e + e - annihilation...

    Office of Scientific and Technical Information (OSTI)

    in e + e - annihilation at NNLO in QCD: The vector current contributions Authors: Gao, Jun ; Zhu, Hua Xing Publication Date: 2014-12-17 OSTI Identifier: 1180238 GrantContract...

  8. VariableR reclustering in multiple top quark events - Oral Presentatio...

    Office of Scientific and Technical Information (OSTI)

    Date: 2015-08-22 OSTI Identifier: 1213193 Report Number(s): SLAC-WP-111 DOE Contract Number: AC02-76SF00515 Resource Type: Technical Report Research Org: SLAC National...

  9. Evidence for single top-quark production in the s-channel in...

    Office of Scientific and Technical Information (OSTI)

    Additional Journal Information: Journal Volume: 756; Journal Issue: C; Journal ID: ISSN 0370-2693 Publisher: Elsevier Sponsoring Org: USDOE Country of Publication: Netherlands ...

  10. Measurement of the charge asymmetry in highly boosted top-quark...

    Office of Scientific and Technical Information (OSTI)

    Additional Journal Information: Journal Volume: 756; Journal Issue: C; Journal ID: ISSN 0370-2693 Publisher: Elsevier Sponsoring Org: USDOE Country of Publication: Netherlands ...

  11. Top-Quark Decay at Next-to-Next-to-Leading Order in QCD (Journal...

    Office of Scientific and Technical Information (OSTI)

    Date: 2013-01-31 OSTI Identifier: 1052981 Report Number(s): SLAC-PUB-15260 Journal ID: ISSN 0031--9007; arXiv:1210.2808 DOE Contract Number: AC02-76SF00515 Resource Type: Journal...

  12. Erratum to: Constraining couplings of top quarks to the Z boson...

    Office of Scientific and Technical Information (OSTI)

    ... Publisher: Springer Berlin Research Org: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States) Sponsoring Org: USDOE Office of Science (SC), High Energy Physics (HEP) ...

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

    SciTech Connect (OSTI)

    Khachatryan, V.

    2014-10-20

    The x-axis of figure 2, lower left panel (Lepton + ? 6 jets + 2 b-tags) should be replaced with 3rd highest CSV output.

  14. Electroweak production of top-quark pairs in e+e- annihilation...

    Office of Scientific and Technical Information (OSTI)

    Bibtex Format Close 0 pages in this document matching the terms "" Search For Terms: Enter terms in the toolbar above to search the full text of this document for pages...

  15. Erratum. 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, V.

    2014-10-20

    The x-axis of figure 2, lower left panel (“Lepton + ≥ 6 jets + 2 b-tags”) should be replaced with “3rd highest CSV output”.

  16. First measurement of the fraction of top-quark pair production through gluon-gluon fusion

    SciTech Connect (OSTI)

    Aaltonen, T.; Maki, T.; Mehtala, P.; Orava, R.; Osterberg, K.; Saarikko, H.; Remortel, N. van; Adelman, J.; Brubaker, E.; Fedorko, W. T.; Grosso-Pilcher, C.; Kim, Y. K.; Kwang, S.; Levy, S.; Paramonov, A. A.; Schmidt, M. A.; Shochet, M.; Wolfe, C.; Yang, U. K.; Yorita, K.

    2008-12-01

    We present the first measurement of {sigma}(gg{yields}tt)/{sigma}(pp{yields}tt). We use 0.96 fb{sup -1} of {radical}(s)=1.96 TeV pp collision data recorded with the CDF II detector at Fermilab. Using charged particles with low transverse momentum in tt events, we find {sigma}(gg{yields}tt)/{sigma}(pp{yields}tt)=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 next-to-leading-order prediction of 0.15{+-}0.05.

  17. Evolution of collectivity as a signal of quark gluon plasma formation in heavy ion collisions

    SciTech Connect (OSTI)

    Mohanty, Payal; Alam, Jan-e; Mohanty, Bedangadas

    2011-08-15

    A measurement for studying the mass dependence of dilepton interferometry in relativistic heavy-ion collision experiments as a tool to characterize the quark gluon phase is proposed. In calculations involving dileptons, we show that the mass dependence of radii extracted from the virtual photon (dilepton) interferometry provide access to the development of collective flow with time. It is argued that the nonmonotonic variation of Hanbury Brown-Twiss radii with invariant mass of the lepton pairs signals the formation of quark gluon plasma in heavy ion collisions. Our proposal of experimentally measuring the ratio, R{sub out}/R{sub side} for dileptons can be used to estimate the average lifetimes of the partonic as well as the hadronic phases.

  18. ARM - Measurement - Cloud top height

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

    top height ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud top height For a given cloud or cloud layer, the highest level of the atmosphere where cloud properties are detectable. Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all

  19. Los Alamos National Laboratory top

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

    top science news of 2012 December 20, 2012 Scientific advances that caught the world's interest LOS ALAMOS, NEW MEXICO, December 20, 2012-In 2012 Los Alamos National Laboratory made its scientific mark in a wide variety of areas, and the stories that caught the public's attention and that of the science community reflect those broad capabilities. Top science stories for the year traveled from the canyons of Mars to the high desert forests of New Mexico, from cosmic particles to the structure of

  20. SW New Mexico Oil Well Formation Tops

    SciTech Connect (OSTI)

    Shari Kelley

    2015-10-21

    Rock formation top picks from oil wells from southwestern New Mexico from scout cards and other sources. There are differing formation tops interpretations for some wells, so for those wells duplicate formation top data are presented in this file.

  1. GreenTops | Open Energy Information

    Open Energy Info (EERE)

    GreenTops Jump to: navigation, search Name: GreenTops Place: Israel Product: Israel-based assemblers of PV-modules mainly for the agricultural comunity. References: GreenTops1...

  2. Final TOPS Rpt-10pt.PDF

    Broader source: Energy.gov (indexed) [DOE]

    OPPORTUNITIES TO INCREASE THE PROLIFERATION RESISTANCE OF GLOBAL CIVILIAN NUCLEAR POWER SYSTEMS (TOPS) REPORT BY THE TOPS TASK FORCE OF THE NUCLEAR ENERGY RESEARCH...

  3. Search for pair-produced vector-like B quarks in proton-proton collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-07-28

    A search for the production of a heavy B quark, having electric charge -1/3 and vector couplings to W, Z, and H bosons, is carried out using proton-proton collision data recorded at the CERN LHC by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb-1 . The B quark is assumed to be pair-produced and to decay in one of three ways: to tW, bZ, or bH. The search is carried out in final states with one, two, and more than two charged leptons, as well as in fully hadronic final states. Each of the channels in the exclusive final-state topologies is designed to be sensitive to specific combinations of the B quark-antiquark pair decays. The observed event yields are found to be consistent with the standard model expectations in all the fi- nal states studied. Our statistical combination of these results was performed and upper limits were set on the cross section of the strongly produced B quark-antiquark pairs as a function of the B quark mass. Additionally, lower limits on the B quark mass between 740 and 900 GeV are set at a 95% confidence level, depending on the values of the branching fractions of the B quark to tW, bZ, and bH. Overall, these limits are the most stringent to date.

  4. Search for Quark Compositeness with the Dijet Centrality Ratio in $pp$ Collisions at $\\sqrt{s}=7$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2010-12-01

    A search for quark compositeness in the form of quark contact interactions, based on hadronic jet pairs (dijets) produced in proton-proton collisions at sqrt(s)=7 TeV, is described. The data sample of the study corresponds to an integrated luminosity of 2.9 inverse picobarns collected with the CMS detector at the LHC. The dijet centrality ratio, which quantifies the angular distribution of the dijets, is measured as a function of the invariant mass of the dijet system and is found to agree with the predictions of the Standard Model. A statistical analysis of the data provides a lower limit on the energy scale of quark contact interactions. The sensitivity of the analysis is such that the expected limit is 2.9 TeV; because the observed value of the centrality ratio at high invariant mass is below the expectation, the observed limit is 4.0 TeV at the 95% confidence level.

  5. Search for Higgs Bosons Produced in Association with b-Quarks

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

    Aaltonen, T

    2012-02-22

    We present a search for neutral Higgs bosons φ decaying into bb¯, produced in association with b quarks in ppb¯ collisions. This process could be observable in supersymmetric models with high values of tan β. The event sample corresponds to 2.6 fb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron collider. We search for an enhancement in the mass of the two leading jets in events with three jets identified as coming from b quarks using a displaced vertex algorithm. A data-driven procedure is used to estimate the dijet mass spectrum of the nonresonant multijetmore » background. The contributions of backgrounds and a possible Higgs boson signal are determined by a two-dimensional fit of the data, using the dijet mass together with an additional variable which is sensitive to the flavor composition of the three tagged jets. We set mass-dependent limits on σ(ppb¯ = φb) x Β(φ= bb¯) which are applicable for a narrow scalar particle φ produced in association with b quarks. We also set limits on tan β in supersymmetric Higgs models including the effects of the Higgs boson width.« less

  6. Search for Higgs Bosons Produced in Association with b-Quarks

    SciTech Connect (OSTI)

    Aaltonen, T

    2012-02-22

    We present a search for neutral Higgs bosons ? decaying into bb?, produced in association with b quarks in ppb? collisions. This process could be observable in supersymmetric models with high values of tan ?. The event sample corresponds to 2.6 fb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron collider. We search for an enhancement in the mass of the two leading jets in events with three jets identified as coming from b quarks using a displaced vertex algorithm. A data-driven procedure is used to estimate the dijet mass spectrum of the nonresonant multijet background. The contributions of backgrounds and a possible Higgs boson signal are determined by a two-dimensional fit of the data, using the dijet mass together with an additional variable which is sensitive to the flavor composition of the three tagged jets. We set mass-dependent limits on ?(ppb? = ?b) x ?(?= bb?) which are applicable for a narrow scalar particle ? produced in association with b quarks. We also set limits on tan ? in supersymmetric Higgs models including the effects of the Higgs boson width.

  7. Dissociation of a heavy meson in the quark medium

    SciTech Connect (OSTI)

    Park, Chanyong

    2010-02-15

    We investigate the dissociation of a heavy meson in the medium composed of light quarks and gluons. In the quark-gluon plasma, the dissociation length of the heavy meson becomes short as the temperature or quark chemical potential increases. On the contrary, in the hadronic phase the dissociation length becomes large as the chemical potential increases, due to the different dissociation mechanism with one used in the quark-gluon plasma.

  8. Adomian Decomposition Method for Quark Gluon Plasma Model

    SciTech Connect (OSTI)

    Constantinescu, Radu; Ionescu, Carmen; Stoicescu, Mihai

    2011-10-03

    The paper investigates the possibility of obtaining analytical solutions for the Quark Gluon Plasma model using the Adomian decomposition method.

  9. Sea quark transverse momentum distributions and dynamical chiral symmetry

    Office of Scientific and Technical Information (OSTI)

    breaking (Conference) | SciTech Connect Sea quark transverse momentum distributions and dynamical chiral symmetry breaking Citation Details In-Document Search Title: Sea quark transverse momentum distributions and dynamical chiral symmetry breaking Recent theoretical studies have provided new insight into the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon at a low scale. The valence quark transverse momentum distributions (q - qbar) are governed by the

  10. Resonance searches with the $t\\overline{t}$ Invariant Mass Distribution measured with the D\\O\\, Experiment at $\\sqrt{s}=1.96\\,\\textrm{TeV}

    SciTech Connect (OSTI)

    Schliephake, Thorsten Dirk; /Wuppertal U.

    2010-06-01

    Understanding the universe, its birth and its future is one of the biggest motivations in physics. In order to understand the cosmos, the fundamental particles forming the universe, the components our matter is built of need to be known and understood. Over time physicists have built a theory which describes the physics of the known fundamental particles very well: the Standard Model (SM) of particle physics. The SM describes the particles, their interactions and phenomena with high precision. So far no proven deviations from the SM have been found, though recently evidence for possible physics beyond the SM has been observed. The SM is not describing the mass of the elementary particles however and even with the addition of the Higgs mechanism giving mass to the particles, we have no full theory for all four fundamental forces. We know the model needs to be extended or replaced by another one, as gravitation is not included in the SM. Having a theory which describes all fundamental particles found so far and all but one fundamental interaction is a great success. However, all this describes about 4% of the universe we live in. 23% is dark matter and 73% is dark energy. Dark matter is believed to interact only through gravity and maybe the weak force, which makes it hardly observable. Dark energy is even more elusive. Among other theories the cosmologic constant and scalar fields are discussed to describe it. One should also note that other models exist which for example modify the Newtonian law of gravity. The Higgs mechanism has become the most popular model for mass generation. Alternative theories like Super Symmetry (SUSY), large Extra Dimensions, Technicolor, String Theory, to name just a few, have spread to describe the necessary mass generation or new particles. As proof for new physics beyond the SM has not been found yet, one assumes that new physics will manifest itself at a larger energy scale and therefore a higher particle mass. Particles with high masses are therefore presumed to be a window to test the SM for deviations caused by new physics. The heaviest fundamental particle which is in our reach is the top quark. Its mass is almost as large as that of a complete tungsten atom. It is so heavy, that it decays faster than it can hadronize. It seems the perfect probe to study new physics at the moment. In this analysis the top quark is used as a probe to search for a new resonance, whose properties are similar to a SM Z boson but is much more massive. This analysis will study t{bar t} decays to search for an excess in the invariant mass distribution of the t{bar t} pairs. Resonant states are suggested for massive Z-like bosons in extended gauge theories, Kaluza Klein states of the gluon or Z, axigluons, topcolor, and other beyond the Standard Model theories. Independent of the exact model a resonant production mechanism should be visible in the t{bar t} invariant mass distribution. In this thesis a model-independent search for a narrow-width heavy resonance X decaying into t{bar t} is performed. In the SM, the top quark decays into a W boson and a b quark nearly 100% of the time, which has been proven experimentally, too. The t{bar t} event signature is fully determined by the W boson decay modes. In this analysis, only the lepton+jets final state, which results from the leptonic decay of one of the W bosons and the hadronic decay of the other, is considered. The event signature is an isolated electron or muon with high transverse momentum, large transverse energy imbalance due to the undetected neutrino, and at least three jets, two of which result from the hadronization of b quarks.

  11. Effects of quark family nonuniversality in SU(3){sub c} x SU(4){sub L} x U(1){sub X} models

    SciTech Connect (OSTI)

    Nisperuza, Jorge L.; Sanchez, Luis A.

    2009-08-01

    Flavor changing neutral currents arise in the SU(3){sub c} x SU(4){sub L} x U(1){sub X} extension of the standard model because anomaly cancellation among the fermion families requires one generation of quarks to transform differently from the other two under the gauge group. In the weak basis the distinction between quark families is meaningless. However, in the mass eigenstates basis, the Cabibbo-Kobayashi-Maskawa mixing matrix motivates us to classify left-handed quarks in families. In this sense there are, in principle, three different assignments of quark weak eigenstates into mass eigenstates. In this work, by using measurements at the Z pole, atomic parity violation data, and experimental input from neutral meson mixing, we examine two different models without exotic electric charges based on the 3-4-1 symmetry, and address the effects of quark family nonuniversality on the bounds on the mixing angle between two of the neutral currents present in the models and on the mass scales M{sub Z{sub 2}} and M{sub Z{sub 3}} of the new neutral gauge bosons predicted by the theory. The heaviest family of quarks must transform differently in order to keep lower bounds on M{sub Z{sub 2}} and M{sub Z{sub 3}} as low as possible without violating experimental constraints.

  12. Top Innovations 2012 | Department of Energy

    Energy Savers [EERE]

    Residential Buildings » Building America » Top Innovations 2012 Top Innovations 2012 On this page, you will find Building America's Top Innovations from 1995 through 2012, with links to a profile describing each innovation. Note that some categories may not have a top innovation each year. Flow chart graphic 1. Advanced Technologies and Practices Top Innovations in this category cover research in thermal enclosure improvements, HVAC components, ventilation and other health and safety issues.

  13. Building America Top Innovations | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Research » Building America Top Innovations Building America Top Innovations New Top Innovations are awarded annually for outstanding Building America research achievements. Each year, Building America selects cutting-edge Top Innovations that demonstrate the value of investing in high-performance research and development and guide the industry toward more energy-efficient, healthier, and longer lasting homes. Building America Top Innovations align with and support every aspect of the home

  14. Quark-gluon plasma (Selected Topics)

    SciTech Connect (OSTI)

    Zakharov, V. I.

    2012-09-15

    Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.

  15. Quark-Gluon Plasma Model and Origin of Magic Numbers

    SciTech Connect (OSTI)

    Ghahramany, N.; Ghanaatian, M.; Hooshmand, M.

    2008-04-21

    Using Boltzman distribution in a quark-gluon plasma sample it is possible to obtain all existing magic numbers and their extensions without applying the spin and spin-orbit couplings. In this model it is assumed that in a quark-gluon thermodynamic plasma, quarks have no interactions and they are trying to form nucleons. Considering a lattice for a central quark and the surrounding quarks, using a statistical approach to find the maximum number of microstates, the origin of magic numbers is explained and a new magic number is obtained.

  16. Meson properties at finite temperature in a three flavor nonlocal chiral quark model with Polyakov loop

    SciTech Connect (OSTI)

    Contrera, G. A.; Dumm, D. Gomez; Scoccola, Norberto N.

    2010-03-01

    We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles and decay constants. The critical temperature is found to be T{sub c{approx_equal}}202 MeV, in better agreement with lattice results than the value recently obtained in the local SU(3) PNJL model. It is seen that above T{sub c} pseudoscalar meson masses get increased, becoming degenerate with the masses of their chiral partners. The temperatures at which this matching occurs depend on the strange quark composition of the corresponding mesons. The topological susceptibility shows a sharp decrease after the chiral transition, signalling the vanishing of the U(1){sub A} anomaly for large temperatures.

  17. Effect of quark sector minimal flavor violation on neutrinoless double beta decay

    SciTech Connect (OSTI)

    Dudley, Brian; Kolda, Christopher [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2009-01-01

    The question of whether neutrino masses are Dirac or Majorana is one of the most important, and most difficult, questions remaining in the neutrino sector. Searches for neutrinoless double {beta} decay may help to resolve this question, but are also sensitive to new, higher-dimension {delta}L=2 operators. In this paper we place two phenomenological constraints on these operators at dimension d{<=}11. First, we require that the operators obey the quark flavor symmetries of the standard model, with any violation of the symmetries being due to Yukawa interactions, a scheme known as minimal flavor violation. Second, we require that the operators which generate neutrinoless double {beta} decay, and any operators related by the flavor symmetries, do not induce neutrino masses above the experimental and astrophysical limits. We find that these requirements severely constrain the operators which can violate lepton number, such that most can no longer contribute to neutrinoless double {beta} decay at observable rates. It is noteworthy that quark flavor symmetries can play such a strong role in constraining new leptonic physics, even when that physics is not quark flavor changing. Those few operators that can mimic a Majorana neutrino mass then appear with cutoffs below a TeV, and represent new physics which could be directly probed at the LHC or a future linear collider.

  18. One-loop gluon amplitude for heavy-quark production at next-to-next-to-leading order

    SciTech Connect (OSTI)

    Anastasiou, Charalampos; Aybat, S. Mert

    2008-12-01

    We compute the one-loop QCD amplitude for the process gg{yields}QQ in dimensional regularization through order {epsilon}{sup 2} in the dimensional regulator and for arbitrary quark mass values. This result is an ingredient of the next-to-next-to-leading order cross section for heavy-quark production at hadron colliders. The calculation is performed in conventional dimensional regularization using well-known reduction techniques as well as a method based on recent ideas for the functional form of one-loop integrands in four dimensions.

  19. NAPSR Top Priorities for 2014

    Broader source: Energy.gov (indexed) [DOE]

    NAPSR Top Priorities for 2014 1. Final Rule regarding: Gathering Lines NAPSR supports a rule outlining a clear definition of the beginning and endpoints of gathering lines. The current regulations leave the beginning and endpoint open to interpretation depending on the configuration and location of process equipment. NAPSR supports a rule subjecting all gathering lines, including those operating in Class 1 locations, to Code of Federal Regulation requirements. Requirement limitations may be

  20. WIPP Receives Top Mine Safety Award

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

    Top Mine Safety Award CARLSBAD, N.M., September 18, 2013 - The U.S. Department of Energy's (DOE) Waste Isolation Pilot Plant (WIPP) received top safety honors from the New Mexico...

  1. Quarkonia and heavy-quark relaxation times in the quark-gluon plasma

    SciTech Connect (OSTI)

    Riek, F.; Rapp, R.

    2010-09-15

    A thermodynamic T-matrix approach for elastic two-body interactions is employed to calculate spectral functions of open and hidden heavy-quark systems in the quark-gluon plasma. This enables the evaluation of quarkonium bound-state properties and heavy-quark diffusion on a common basis and thus to obtain mutual constraints. The two-body interaction kernel is approximated within a potential picture for spacelike momentum transfers. An effective field-theoretical model combining color-Coulomb and confining terms is implemented with relativistic corrections and for different color channels. Four pertinent model parameters, characterizing the coupling strengths and screening, are adjusted to reproduce the color-average heavy-quark free energy as computed in thermal lattice QCD. The approach is tested against vacuum spectroscopy in the open (D, B) and hidden ({Psi} and {Upsilon}) flavor sectors, as well as in the high-energy limit of elastic perturbative QCD scattering. Theoretical uncertainties in the static reduction scheme of the four-dimensional Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are used to calculate Euclidean correlators which are discussed in light of lattice QCD results, while heavy-quark relaxation rates and diffusion coefficients are extracted utilizing a Fokker-Planck equation.

  2. Supercomputing Challenge top winners: Los Alamos schools

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

    Supercomputing Challenge top winners: Los Alamos schools Supercomputing Challenge top winners: Los Alamos schools Cole Kendrick won the top prize for his research project, "Computer Simulation of Dark Matter Effects on Galaxy Rotation". April 26, 2011 Cole Kendrick Cole Kendrick Contact Steve Sandoval Communications Office (505) 665-9206 Email LOS ALAMOS, New Mexico, April 26, 2011-Los Alamos Middle School student Cole Kendrick won the top prize in the 21st New Mexico Supercomputing

  3. Materials Technologies: Goals, Strategies, and Top Accomplishments

    SciTech Connect (OSTI)

    2010-08-02

    Fact sheet describing the goals, strategies, and top accomplishments of the Materials Technologies subprogram of the Vehicle Technologies Program.

  4. Infrastructure Development - Building America Top Innovations | Department

    Office of Environmental Management (EM)

    of Energy Infrastructure Development - Building America Top Innovations Infrastructure Development - Building America Top Innovations August 25, 2014 - 11:23am Addthis Infrastructure Development - Building America Top Innovations Top Innovations in this category include research results that have influenced codes and standards and improvements in education and the transaction process. Educating Professionals Projects are underway in this category. Check back for profiles to be posted soon.

  5. Table-top job analysis

    SciTech Connect (OSTI)

    Not Available

    1994-12-01

    The purpose of this Handbook is to establish general training program guidelines for training personnel in developing training for operation, maintenance, and technical support personnel at Department of Energy (DOE) nuclear facilities. TTJA is not the only method of job analysis; however, when conducted properly TTJA can be cost effective, efficient, and self-validating, and represents an effective method of defining job requirements. The table-top job analysis is suggested in the DOE Training Accreditation Program manuals as an acceptable alternative to traditional methods of analyzing job requirements. DOE 5480-20A strongly endorses and recommends it as the preferred method for analyzing jobs for positions addressed by the Order.

  6. MHD Integrated Topping Cycle Project

    SciTech Connect (OSTI)

    Not Available

    1992-07-01

    This eighteenth quarterly technical progress report of the MHD Integrated Topping cycle Project presents the accomplishments during the period November 1, 1991 to January 31, 1992. The precombustor is fully assembled. Manufacturing of all slagging stage components has been completed. All cooling panels were welded in place and the panel/shell gap was filled with RTV. Final combustor assembly is in progress. The low pressure cooling subsystem (LPCS) was delivered to the CDIF. Second stage brazing issues were resolved. The construction of the two anode power cabinets was completed.

  7. Materials Technologies: Goals, Strategies, and Top Accomplishments

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (Brochure), Vehicle Technologies Program (VTP) | Department of Energy Materials Technologies: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) Materials Technologies: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) PDF icon materials_tech_goals.pdf More Documents & Publications Vehicle Technologies Program: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) FY 2009

  8. MHD Integrated Topping Cycle Project

    SciTech Connect (OSTI)

    Not Available

    1992-03-01

    The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW{sub t}) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW{sub t} power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990's, an engineering data base on the reliability, availability, maintainability and performance of the system will be available to allow scaleup of the prototypical designs to the next development level. This Sixteenth Quarterly Technical Progress Report covers the period May 1, 1991 to July 31, 1991.

  9. MHD Integrated Topping Cycle Project

    SciTech Connect (OSTI)

    Not Available

    1992-01-01

    The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois {number sign}6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.

  10. Mass and mixing angle patterns in the Standard Model and its material Supersymmetric Extension

    SciTech Connect (OSTI)

    Ramond, P.

    1992-01-01

    Using renormalization group techniques, we examine several interesting relations among masses and mixing angles of quarks and lepton in the Standard Model of Elementary Particle Interactions as a functionof scale. We extend the analysis to the minimal Supersymmetric Extension to determine its effect on these mass relations. For a heavy to quark, and minimal supersymmetry, most of these relations, can be made to agree at one unification scale.

  11. Recent Developments in Heavy Quark and Quarkonium Production...

    Office of Scientific and Technical Information (OSTI)

    corrections to the QCD factorization theorem. A power correction called heavy-quark recombination can economically explain these asymmetries with a few universal parameters....

  12. Sea quark transverse momentum distributions and dynamical chiral...

    Office of Scientific and Technical Information (OSTI)

    The qualitative difference between valence and sea quark intrinsic psub T. distributions ... May 2013 Publisher: World Scientific Research Org: Thomas Jefferson National ...

  13. Quark-Gluon Plasma: a New State of Matter

    ScienceCinema (OSTI)

    Brookhaven Lab

    2010-01-08

    Physicist Peter Steinberg explains the nature of the quark gluon plasma (QGP), a new state of matter produced at Brookhaven Lab's Relativistic Heavy Ion Collider (RHIC).

  14. Quark-Gluon Plasma: a New State of Matter

    SciTech Connect (OSTI)

    Brookhaven Lab

    2009-07-08

    Physicist Peter Steinberg explains the nature of the quark gluon plasma (QGP), a new state of matter produced at Brookhaven Lab's Relativistic Heavy Ion Collider (RHIC).

  15. Electromagnetic form factors and the hypercentral constituent quark model

    SciTech Connect (OSTI)

    Sanctis, M. De; Giannini, M. M.; Santopinto, E.; Vassallo, A.

    2007-12-15

    We present new results concerning the electromagnetic form factors of the nucleon using a relativistic version of the hypercentral constituent quark model and a relativistic current.

  16. Building America Top Innovations Hall of Fame Profile - Building...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Top Innovations Propel the Home Building Industry toward Higher Performance Building America Top Innovations Hall of Fame Profile - Building America's Top Innovations Propel the...

  17. EM Recovery Act Top Line Messages | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Top Line Messages EM Recovery Act Top Line Messages The lastest Recovery Act performance related information and metrics. PDF icon EM Recovery Act Top Line Messages - April, 2013...

  18. MHD Integrated Topping Cycle Project

    SciTech Connect (OSTI)

    Not Available

    1992-07-01

    This seventeenth quarterly technical progress report of the MHD Integrated Topping Cycle Project presents the accomplishments during the period August 1, 1991 to October 31, 1991. Manufacturing of the prototypical combustor pressure shell has been completed including leak, proof, and assembly fit checking. Manufacturing of forty-five cooling panels was also completed including leak, proof, and flow testing. All precombustor internal components (combustion can baffle and swirl box) were received and checked, and integration of the components was initiated. A decision was made regarding the primary and backup designs for the 1A4 channel. The assembly of the channel related prototypical hardware continued. The cathode wall electrical wiring is now complete. The mechanical design of the diffuser has been completed.

  19. Chromodynamic fluctuations in quark-gluon plasma

    SciTech Connect (OSTI)

    Mrowczynski, Stanislaw

    2008-05-15

    Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary, and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.

  20. LANL named 2010 top corporate volunteer organization

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

    2010 top corporate volunteer organization LANL named 2010 top corporate volunteer organization The Laboratory ranked ahead of dozens of other qualifying companies with 10,000 or more employees. May 18, 2011 Building and painting birdhouses with children in Santa Fe Building and painting birdhouses with children in Santa Fe. Contact Steve Sandoval Communications Office (505) 665-9206 Email LOS ALAMOS, New Mexico, May 18, 2011-Los Alamos National Laboratory has earned an award as the top corporate

  1. Unvented, Conditioned Crawlspaces - Building America Top Innovation |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Unvented, Conditioned Crawlspaces - Building America Top Innovation Unvented, Conditioned Crawlspaces - Building America Top Innovation This photo shows the interior of a framed crawlspace with insulation installed. This Top Innovation profile highlights Building America research into the benefits of closed, conditioned crawlspaces over traditional vented crawlspaces. Crawlspace vents are supposed to prevent moisture problems, based on the assumption that fresh air

  2. Vapor Retarder Classification - Building America Top Innovation |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Vapor Retarder Classification - Building America Top Innovation Vapor Retarder Classification - Building America Top Innovation Photo of a vapor retarder classification. Air-tight and well-insulated homes have little or no tolerance for drying if they get wet; moisture control is critical. This Top Innovation profile describes Building America research that established vapor retarder classifications and appropriate applications that has been instrumental in the market

  3. Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

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

    Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; et al

    2012-01-01

    A large set of cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W',more » is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π+ and π-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.« less

  4. Unvented, Conditioned Crawlspaces - Building America Top Innovation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    This Top Innovation profile highlights Building America research into the benefits of ... Find more case studies of Building America projects across the country that demonstrate ...

  5. Vapor Retarder Classification - Building America Top Innovation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    This Top Innovation profile describes Building America research that established vapor ... Find other case studies of Building America projects across the country that utilizes ...

  6. Basement Insulation Systems - Building America Top Innovation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    See an example of this Top Innovation in action. Find more case studies of Building America projects across the country that demonstrate advanced basement insulation systems. View ...

  7. Furnace Blower Performance Improvements - Building America Top...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    See an example of this Top Innovation in action. Find more case studies of Building America projects across the country that demonstrate optimization of furnace blowers. View other ...

  8. Mesa Top Photovoltaic Array (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2009-07-01

    Fact sheet overview of the Mesa Top Photovoltaic Array project implemented by the Department of Energy Golden Office and National Renewable Energy Laboratory.

  9. Dateline Los Alamos: Top Science News

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

    Science News of 2014 December 22, 2014 Dateline Los Alamos: Top Science News of 2014 Biosurveillance, secure computing, alternative energy, unique capabilities highlight the year....

  10. Vehicle Technologies Program: Goals, Strategies, and Top Accomplishmen...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Program: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) Vehicle Technologies Program: Goals, Strategies, and Top Accomplishments ...

  11. MHD Integrated Topping Cycle Project

    SciTech Connect (OSTI)

    Not Available

    1992-02-01

    This fourteenth quarterly technical progress report of the MHD Integrated Topping Cycle Project presents the accomplishments during the period November 1, 1990 to January 31, 1991. Testing of the High Pressure Cooling Subsystem electrical isolator was completed. The PEEK material successfully passed the high temperature, high pressure duration tests (50 hours). The Combustion Subsystem drawings were CADAM released. The procurement process is in progress. An equipment specification and RFP were prepared for the new Low Pressure Cooling System (LPCS) and released for quotation. Work has been conducted on confirmation tests leading to final gas-side designs and studies to assist in channel fabrication.The final cathode gas-side design and the proposed gas-side designs of the anode and sidewall are presented. Anode confirmation tests and related analyses of anode wear mechanisms used in the selection of the proposed anode design are presented. Sidewall confirmation tests, which were used to select the proposed gas-side design, were conducted. The design for the full scale CDIF system was completed. A test program was initiated to investigate the practicality of using Avco current controls for current consolidation in the power takeoff (PTO) regions and to determine the cause of past current consolidation failures. Another important activity was the installation of 1A4-style coupons in the 1A1 channel. A description of the coupons and their location with 1A1 channel is presented herein.

  12. Gauge bosons and heavy quarks: Proceedings of Summer Institute on Particle Physics

    SciTech Connect (OSTI)

    Hawthorne, J.F.

    1991-01-01

    This report contains papers on the following topics: Z decays and tests of the standard model; future possibilities for LEP; studies of the interactions of electroweak gauge bosons; top quark topics; the next linear collider; electroweak processes in hadron colliders; theoretical topics in B-physics; experimental aspects of B-physics; B-factory storage ring design; rare kaon decays; CP violation in K{sup 0} decays at CERN; recent K{sup 0} decay results from Fermilab E-731; results from LEP on heavy quark physics; review of recent results on heavy flavor production; weak matrix elements and the determination of the weak mixing angles; recent results from CLEO I and a glance at CLEO II data; recent results from ARGUS; neutrino lepton physics with the CHARM 2 detector; recent results from the three TRISTAN experiments; baryon number violation at high energy in the standard model: fact or fiction New particle searches at LEP; review of QCD at LEP; electroweak interactions at LEP; recent results on W physics from the UA2 experiment at the CERN {rho}{bar {rho}} collider; B physics at CDF; and review of particle astrophysics.

  13. Predictions for the Higgs Mass from the Stability and Triviality Conditions

    SciTech Connect (OSTI)

    Solis R, H. Gabriel; Juarez W, S. Rebeca; Kielanowski, P.

    2006-09-25

    In the context of the Standard Model (SM), we use the one-loop and two-loop Renormalization Group Equations (RGE) in order to analyze the evolution of the Higgs quartic coupling {lambda}H in the interval [mt, EGU], where mt is the mass of the top quark and EGU = 1014GeV. The analytical solution for the one-loop differential equation (Riccati type) is obtained and analyzed and in the two-loop case we obtain a numerical solution which takes into account all the parameters (couplings) at the same order of approximation. In both cases, we restrict the possible initial values for {lambda}H by means of imposing the triviality and stability conditions which determine the range of energies where the SM is valid. We obtain the following bounds: 0.387 < {lambda}H < 0.623 for the one-loop case and 0.360 < {lambda}H < 0.628 for the two-loop case. These results determine the interval of the possible Higgs mass values: 151.9 < MH < 192.3 GeV, 143.8 < MH < 190.3 GeV for the one-loop and two-loop cases, respectively.

  14. Weak Interaction Models with New Quarks and Right-handed Currents

    DOE R&D Accomplishments [OSTI]

    Wilczek, F. A.; Zee, A.; Kingsley, R. L.; Treiman, S. B.

    1975-06-01

    We discuss various weak interaction issues for a general class of models within the SU(2) x U(1) gauge theory framework, with special emphasis on the effects of right-handed, charged currents and of quarks bearing new quantum numbers. In particular we consider the restrictions on model building which are imposed by the small KL - KS mass difference and by the .I = = rule; and we classify various possibilities for neutral current interactions and, in the case of heavy mesons with new quantum numbers, various possibilities for mixing effects analogous to KL - KS mixing.

  15. TOP500 Supercomputers for June 2002

    SciTech Connect (OSTI)

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2002-06-20

    19th Edition of TOP500 List of World's Fastest Supercomputers Released MANNHEIM, Germany; KNOXVILLE, Tenn.;&BERKELEY, Calif. In what has become a much-anticipated event in the world of high-performance computing, the 19th edition of the TOP500 list of the worlds fastest supercomputers was released today (June 20, 2002). The recently installed Earth Simulator supercomputer at the Earth Simulator Center in Yokohama, Japan, is as expected the clear new number 1. Its performance of 35.86 Tflop/s (trillions of calculations per second) running the Linpack benchmark is almost five times higher than the performance of the now No.2 IBM ASCI White system at Lawrence Livermore National Laboratory (7.2 Tflop/s). This powerful leap frogging to the top by a system so much faster than the previous top system is unparalleled in the history of the TOP500.

  16. Basic features of the pion valence-quark distribution function

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

    Chang, Lei; Mezrag, Cdric; Moutarde, Herv; Roberts, Craig D.; Rodrguez-Quintero, Jose; Tandy, Peter C.

    2014-10-07

    The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbowladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables amorerealistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, q?(x); namely, at a characteristic hadronic scale, q?(x)~(1-x)2 for x?0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.less

  17. Measurement of $\\mathrm{ t \\bar{t} } $ production with additional jet activity, including b quark jets, in the dilepton decay channel using pp collisions at $\\sqrt{s} =$ 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-10-13

    Jet multiplicity distributions in top quark pair (tt) events are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC using a data set corresponding to an integrated luminosity of 19.7 fb-1. The measurement is performed in the dilepton decay channels (e+e-,?+?- and e??). Furthermore, the absolute and normalized differential cross sections for tt production are measured as a function of the jet multiplicity in the event for different jet transverse momentum thresholds and the kinematic properties of the leading additional jets. The differential tt-b and tt-bb- cross sections are presented for the first time as a function of the kinematic properties of the leading additional b jets. Furthermore, the fraction of events without additional jets above a threshold is measured as a function of the transverse momenta of the leading additional jets and the scalar sum of the transverse momenta of all additional jets. Finally, the data are compared and found to be consistent with predictions from several perturbative quantum chromodynamics event generators and a next-to-leading ordercalculation.

  18. Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at $sqrt{s} = 7$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2011-05-01

    Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at s? = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV is obtained at the 95% confidence level.

  19. Search for neutral Higgs bosons decaying to tau pairs produced in association with b-quarks at s**(1/2)=1.96 TeV

    SciTech Connect (OSTI)

    Herner, Kenneth Richard; /SUNY, Stony Brook

    2008-12-01

    We report results from a search for neutral Higgs bosons decaying to tau pairs produced in association with a b-quark in 1.6 fb{sup -1} of data taken from June 2006 to March 2008 with the D0 detector at Fermi National Accelerator Laboratory. The final state includes a muon, hadronically decaying tau, and jet identified as coming from a b-quark. We set cross section times branching ratio limits on production of such neutral Higgs bosons {phi} in the mass range from 90 GeV to 160 GeV. Exclusion limits are set at the 95% Confidence Level for several supersymmetric scenarios.

  20. Neutrons and Quarks Share Dual Nature | Jefferson Lab

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

    Neutrons and Quarks Share Dual Nature Mosiac Title Mosiac Title: No1 beginnning, click for copyright information. When you stand back to admire a mosaic, such as the one to the left, you see the overall image. But look closely, and you can see the individual tiles and binding mortar that make up the mosaic. Physicists do much the same thing when they study protons and neutrons. Crack open a proton or a neutron, and you'll find quarks swarming around inside. Among the quarks are a host of other

  1. B-Bbar Mixing and Matching with Fermilab Heavy Quarks

    SciTech Connect (OSTI)

    Evans, Richard Todd; Gamiz, Elvira; El-Khadra, Aida; Kronfeld, Andreas; /Fermilab

    2009-11-01

    We discuss the matching procedure for heavy-light 4-quark operators using the Fermilab method for heavy quarks and staggered fermions for light quarks. These ingredients enable us to construct the continuum-limit operator needed to determine the oscillation frequency of neutral B mesons. The matching is then carried out at the one-loop level. We also present an updated preliminary result for the SU(3)-breaking ratio {zeta}, based on calculations using the MILC Collaboration's ensembles of lattice gauge fields.

  2. Moving Quarks Help Solve Proton Spin Puzzle | Jefferson Lab

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

    Moving Quarks Help Solve Proton Spin Puzzle NEWPORT NEWS, VA., Sept. 11, 2008 - New theory work at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility has shown that more than half of the spin of the proton is the result of the movement of its building blocks: quarks. The result, published in the Sept. 5 issue of Physical Review Letters, agrees with recent experiments and supercomputer calculations. It was thought that the spin of the proton would come from its quarks,

  3. NERSC Supports Top Breakthroughs of 2013

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

    Supports 2013's Top Breakthroughs NERSC Supports Top Breakthroughs of 2013 December 20, 2013 Linda Vu, +1 510 495 2402, lvu@lbl.gov Research supported by NERSC is being honored by end-of-year reviews in two leading magazines: Physics World and WIRED. The IceCube South Pole Neutrino Observatory was notably named to both lists, being honored as the most important discovery by Physics World. Three of Physics World's top 10 breakthroughs of 2013 went to discoveries that used NERSC resources. In

  4. Fermilab | Newsroom | Press Releases | September 27, 2012: QuarkNet...

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

    RELEASE QuarkNet program receives 6.1 million NSF award to advance science education Hi-res | Med-res Steven Grosland, physics teacher at Glenbrook South High School in...

  5. Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-11

    A search for neutral Higgs bosons decaying into a bb¯ quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan β. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb–1. The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limits on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios, mhmax, mhmod+, mhmod–, light-stau and light-stop. Observed 95% confidence level upper limits on tan β, ranging from 14 to 50, are obtained in the mhmod+ benchmark scenario.

  6. Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

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

    Khachatryan, Vardan

    2015-11-11

    A search for neutral Higgs bosons decaying into a bb¯ quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan β. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb–1. The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limitsmore » on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios, mhmax, mhmod+, mhmod–, light-stau and light-stop. Observed 95% confidence level upper limits on tan β, ranging from 14 to 50, are obtained in the mhmod+ benchmark scenario.« less

  7. Dark matter and dark energy from quark bag model

    SciTech Connect (OSTI)

    Brilenkov, Maxim; Eingorn, Maxim; Jenkovszky, Laszlo; Zhuk, Alexander E-mail: maxim.eingorn@gmail.com E-mail: ai.zhuk2@gmail.com

    2013-08-01

    We calculate the present expansion of our Universe endowed with relict colored objects quarks and gluons that survived hadronization either as isolated islands of quark-gluon ''nuggets'' or spread uniformly in the Universe. In the first scenario, the QNs can play the role of dark matter. In the second scenario, we demonstrate that uniform colored objects can play the role of dark energy providing the late-time accelerating expansion of the Universe.

  8. MARTINI event generator for heavy quarks: Initialization, parton evolution,

    Office of Scientific and Technical Information (OSTI)

    and hadronization (Journal Article) | DOE PAGES MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization « Prev Next » Title: MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Authors: Young, Clint ; Schenke, Björn ; Jeon, Sangyong ; Gale, Charles Publication Date: 2012-09-10 OSTI Identifier: 1103304 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional Journal Information: Journal

  9. MARTINI event generator for heavy quarks: Initialization, parton evolution,

    Office of Scientific and Technical Information (OSTI)

    and hadronization (Journal Article) | SciTech Connect MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Citation Details In-Document Search Title: MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Authors: Young, Clint ; Schenke, Björn ; Jeon, Sangyong ; Gale, Charles Publication Date: 2012-09-10 OSTI Identifier: 1103304 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional

  10. Anomalies of quark diagrams in the decay eta. --> pi. /sup 0/. gamma gamma. and the quark structure of the scalar meson delta(980)

    SciTech Connect (OSTI)

    Ivanov, A.N.; Troitskaya, N.I.

    1982-08-01

    The width of the decay eta..--> pi../sup 0/..gamma gamma.. is calculated in the model of dominance of quark loop anomalies. We investigate the contribution of the scalar meson delta(980) for two versions of its quark structure: a) the delta meson is a /sup 2/P/sub 0/ state of a quark-antiquark pair, b) the delta meson is a quark molecule of the type qqqq. We discuss the results.

  11. Wind Energy Program: Top 10 Program Accomplishments

    Broader source: Energy.gov [DOE]

    Brochure on the top accomplishments of the Wind Energy Program, including the development of large wind machines, small machines for the residential market, wind tunnel testing, computer codes for modeling wind systems, high definition wind maps, and successful collaborations.

  12. Top Low- or No-Cost Improvements

    Broader source: Energy.gov [DOE]

    This presentation describes the top low- or no-cost projects to improve energy efficiency as identified in energy assessments performed by DOE and by the Industrial Assessment Centers.

  13. Top 10 - DOE Directives, Delegations, and Requirements

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

    Top 10 by Website Administrator The 10 most frequently accessed documents from last month. Document Viewed Number of Times Viewed DOE O 413.3B, Program and Project Management for...

  14. Diesel prices top $4 per gallon

    U.S. Energy Information Administration (EIA) Indexed Site

    Diesel prices top 4 per gallon The U.S. average retail price for on-highway diesel fuel surpassed the four dollar mark for the first time this year. Prices rose to 4.02 a gallon...

  15. Top 10 science stories of the year

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

    Top 10 science stories of the year Top 10 science stories of the year From supercomputers and climate modeling, to cybersecurity and cancer treatments, Los Alamos worked hard in 2015 to advance science that helps address many of our most pressing challenges. December 23, 2015 From supercomputers and climate modeling, to cybersecurity and cancer treatments, Los Alamos National Laboratory worked hard in 2015 to advance science that helps address many of our most pressing challenges. Ocean currents

  16. Measurement of the Top Pair Production Cross Section in the Lepton + Jets Channel Using a Jet Flavor Discriminant

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

    Aaltonen, T.

    2011-08-01

    We present a new method to measure the top quark pair production cross section and the background rates with data corresponding to an integrated luminosity of 2.7 fb-1 from p p̄ collisions at √s = 1.96 TeV collected with the CDF II Detector. We select events with a single electron or muon candidate, missing transverse energy, and at least one b-tagged jet. We perform a simultaneous fit to a jet flavor discriminant across nine samples defined by the number of jets and b-tags. An advantage of this approach is that many systematic uncertainties are measured in situ and inversely scalemore » with integrated luminosity. We measure a top cross section of σtt¯ = 7.64 ± 0.57 (stat + syst) ± 0.45 (luminosity) pb.« less

  17. Measurement of the Top Pair Production Cross Section in the Lepton + Jets Channel Using a Jet Flavor Discriminant

    SciTech Connect (OSTI)

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

    2011-08-01

    We present a new method to measure the top quark pair production cross section and the background rates with data corresponding to an integrated luminosity of 2.7 fb-1 from p p? collisions at ?s = 1.96 TeV collected with the CDF II Detector. We select events with a single electron or muon candidate, missing transverse energy, and at least one b-tagged jet. We perform a simultaneous fit to a jet flavor discriminant across nine samples defined by the number of jets and b-tags. An advantage of this approach is that many systematic uncertainties are measured in situ and inversely scale with integrated luminosity. We measure a top cross section of ?tt? = 7.64 0.57 (stat + syst) 0.45 (luminosity) pb.

  18. Big Bang Day: 5 Particles - 2. The Quark

    SciTech Connect (OSTI)

    None

    2009-10-07

    Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 2. The Quark "Three Quarks for Master Mark! Sure he hasn't got much of a bark." James Joyce's Finnegans Wake left its mark on modern physics when physicist Murray Gell Mann proposed this name for a group of hypothetical subatomic particles that were revealed in 1960 as the fundamental units of matter. Basic particles it seems are made up of even more basic units called quarks that make up 99.9% of visible material in the universe.. But why do we know so little about them? Quarks have never been seen as free particles but instead, inextricably bound together by the Strong Force that in turn holds the atomic nucleus together. This is the hardest of Nature's fundamental forces to crack, but recent theoretical advances, mean that the properties of the quark are at last being revealed.

  19. Big Bang Day: 5 Particles - 2. The Quark

    ScienceCinema (OSTI)

    None

    2011-04-25

    Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 2. The Quark "Three Quarks for Master Mark! Sure he hasn't got much of a bark." James Joyce's Finnegans Wake left its mark on modern physics when physicist Murray Gell Mann proposed this name for a group of hypothetical subatomic particles that were revealed in 1960 as the fundamental units of matter. Basic particles it seems are made up of even more basic units called quarks that make up 99.9% of visible material in the universe.. But why do we know so little about them? Quarks have never been seen as free particles but instead, inextricably bound together by the Strong Force that in turn holds the atomic nucleus together. This is the hardest of Nature's fundamental forces to crack, but recent theoretical advances, mean that the properties of the quark are at last being revealed.

  20. Constituent quark scaling violation due to baryon number transport

    SciTech Connect (OSTI)

    Dunlop J. C.; Lisa, M.A., Sorensen, P.

    2011-10-31

    In ultrarelativistic heavy-ion collisions at {radical}s{sub NN} {approx} 200 GeV, the azimuthal emission anisotropy of hadrons with low and intermediate transverse momentum (p{sub T} {approx}< 4 GeV/c) displays an intriguing scaling. In particular, the baryon (meson) emission patterns are consistent with a scenario in which a bulk medium of flowing quarks coalesces into three-quark (two-quark) 'bags.' While a full understanding of this number-of-constituent-quark (NCQ) scaling remains elusive, it is suggestive of a thermalized bulk system characterized by colored dynamical degrees of freedom - a quark-gluon plasma (QGP). In this scenario, one expects the scaling to break down as the central energy density is reduced below the QGP formation threshold; for this reason, NCQ-scaling violation searches are of interest in the energy scan program at the Relativistic Heavy Ion Collider. However, as {radical}s{sub NN} is reduced, it is not only the initial energy density that changes; there is also an increase in the net baryon number at midrapidity, as stopping transports entrance-channel partons to midrapidity. This phenomenon can result in violations of simple NCQ scaling. Still in the context of the quark coalescence model, we describe a specific pattern for the breakdown of the scaling that includes different flow strengths for particles and their antipartners. Related complications in the search for recently suggested exotic phenomena are also discussed.

  1. Jet conversions in a quark-gluon plasma

    SciTech Connect (OSTI)

    Liu, W.; Ko, C. M.; Zhang, B. W.

    2007-05-15

    Quark and gluon jets traversing through a quark-gluon plasma not only lose their energies but also can undergo flavor conversions. The conversion rates via the elastic q(q)g{yields}gq(q) and the inelastic qq{r_reversible}gg scatterings are evaluated in the lowest order in QCD. Including both jet energy loss and conversions in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we have found a net of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the p/{pi}{sup +} and p/{pi}{sup -} ratios at high transverse momentum. However, a much larger net quark-to-gluon jet conversion rate than the one given by the lowest order QCD is needed to account for the observed similar ratios in central Au+Au and p+p collisions at the same energy. Implications of our results are discussed.

  2. Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states from $t\\bar t$ production at the Tevatron

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

    Abazov, Victor Mukhamedovich

    2015-09-22

    We present a simultaneous measurement of the forward-backward asymmetry and the top-quark polarization in tt production in dilepton final states using 9.7 fb1 of proton-antiproton collisions at ?s=1.96 TeV with the D0 detector. To reconstruct the distributions of kinematic observables we employ a matrix element technique that calculates the likelihood of the possible tt kinematic configurations. After accounting for the presence of background events and for calibration effects, we obtain a forward-backward asymmetry of Att=(15.06.4(stat)4.9(syst))% and a top-quark polarization times spin analyzing power in the beam basis of ?P=(7.210.5(stat)4.2(syst))%, with a correlation of 56% between the measurements. If we constrainmorethe forward-backward asymmetry to its expected standard model value, we obtain a measurement of the top polarization of ?P=(11.39.1(stat)1.9(syst))%. If we constrain the top polarization to its expected standard model value, we measure a forward-backward asymmetry of Att=(17.55.6(stat)3.1(syst))%. A combination with the D0 Att measurement in the lepton+jets final state yields an asymmetry of Att=(11.82.5(stat)1.3(syst))%. Within their respective uncertainties, all these results are consistent with the standard model expectations.less

  3. Measurement of the top quark pair production cross section in the dilepton channel using lepton+track selection

    SciTech Connect (OSTI)

    Wagner, Robert Emil; /Princeton U.

    2008-09-01

    The production cross section for t{bar t} pairs decaying into two lepton final states was measured using data from the D0 detector at Fermilab. The measurement was made using a lepton+track selection, where one lepton is fully identified and the second lepton is observed as an isolated track. This analysis is designed to complement similar studies using two fully identified leptons [1]. The cross section for the lepton+track selection was found to be {sigma} = 5.2{sub -1.4}{sup +1.6}(stat){sub -0.8}{sup +0.9}(syst) {+-} 0.3(lumi) pb. The combined cross section using both the lepton+track data and the data from the electron+electron, electron+muon, and muon+muon samples is: {sigma} = 6.4{sub -0.9}{sup +0.9}(stat){sub -0.7}{sup +0.8}(syst) {+-} 0.4(lumi) pb.

  4. Americas_Next_Top_Energy_Innovator_Fact_Sheet.pdf | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AmericasNextTopEnergyInnovatorFactSheet.pdf AmericasNextTopEnergyInnovatorFactSheet.pdf PDF icon AmericasNextTopEnergyInnovatorFactSheet.pdf More Documents &...

  5. Finite volume effects for nucleon and heavy meson masses

    SciTech Connect (OSTI)

    Colangelo, Gilberto; Fuhrer, Andreas; Lanz, Stefan

    2010-08-01

    We apply the resummed version of the Luescher formula to analyze finite volume corrections to the mass of the nucleon and of heavy mesons. We show that by applying the subthreshold expansion of the scattering amplitudes one can express the finite volume corrections in terms of only a few physical observables and the size of the box. In the case of the nucleon, the available information about the quark mass dependence of these physical quantities is discussed and used to assess the finite volume corrections to the nucleon mass as a function of the quark mass including a detailed analysis of the remaining uncertainties. For heavy mesons, the Luescher formula is derived both fully relativistically and in a nonrelativistic approximation and a first attempt at a numerical analysis is made.

  6. USDOE Top-of-Rail Lubricant Project

    SciTech Connect (OSTI)

    Mohumad F. Alzoubi; George R. Fenske; Robert A. Erck; Amrit S. Boparai

    2002-02-01

    Lubrication of wheel/rail systems has been recognized for the last two decades as a very important issue for railroads. Energy savings and less friction and wear can be realized if a lubricant can be used at the wheel/rail interface. On the other hand, adverse influences are seen in operating and wear conditions if improper or excessive lubrication is used. Also, inefficiencies in lubrication need to be avoided for economic and environmental reasons. The top-of-rail (TOR) lubricant concept was developed by Texaco Corporation to lubricate wheels and rails effectively and efficiently. Tranergy Corporation has been developing its SENTRAEN 2000{trademark} lubrication system for the last ten years, and this revolutionary new high-tech on-board rail lubrication system promises to dramatically improve the energy efficiency, performance, safety, and track environment of railroads. The system is fully computer-controlled and ensures that all of the lubricant is consumed as the end of the train passes. Lubricant quantity dispensed is a function of grade, speed, curve, and axle load. Tranergy also has its LA4000{trademark} wheel and rail simulator, a lubrication and traction testing apparatus. The primary task of this project was collecting and analyzing the volatile and semivolatile compounds produced as the lubricant was used. The volatile organic compounds were collected by Carbotrap cartridges and analyzed by adsorption and gas chromatography/mass spectrometry (GC/MS). The semivolatile fraction was obtained by collecting liquid that dripped from the test wheel. The collected material was also analyzed by GC/MS. Both of these analyses were qualitative. The results indicated that in the volatile fraction, the only compounds on the Environmental Protection Agency's (EPA) Superfund List of Analytes detected were contaminants either in the room air or from other potential contamination sources in the laboratory. Similarly, in the semivolatile fraction none of the detected compounds are on the EPA's Superfund List of Analytes. The major compound in the semivolatile fraction is 1,2-propanediol, which was also found as the major component of the TOR lubricant before testing. Other compounds found in trace quantities either were present in the TOR lubricant or were small fragments from the polymeric component of the TOR lubricant. The second task for Argonne in this project was to investigate the effects of axle load, angle of attack, and quantity of lubricant on lateral friction forces, as well as the consumption time of the TOR lubricant. The second task was to collect and qualitatively identify any volatile and semivolatile compounds produced upon use of the TOR lubricant.

  7. ENERGY STAR for Homes - Building America Top Innovation | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Find case studies of Building America projects across the country that support ENERGY STAR ... America Top Innovations Hall of Fame Profile - Building America's Top Innovations ...

  8. Building America Top Innovations Hall of Fame Profile … High...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... TOP INNOVATIONS BUILDING AMERICA BUILDING AMERICA TOP INNOVATIONS HALL OF FAME PROFILE Habitat affiliates across the country held "blitz builds" to construct homes for Gulf Coast ...

  9. Building America Top Innovations 2014 Profile: California Energy...

    Office of Scientific and Technical Information (OSTI)

    Selection This 2014 Top Innovation profile describes Building America research on ... Country of Publication: United States Language: English Subject: Building America; top ...

  10. Programs and Contractors -Top Tips for Successful Relationships...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Programs and Contractors -Top Tips for Successful Relationships (101) Programs and Contractors -Top Tips for Successful Relationships (101) Better Buildings Residential Network ...

  11. Building Science-Based Climate Maps - Building America Top Innovation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Building Science-Based Climate Maps - Building America Top Innovation Building Science-Based Climate Maps - Building America Top Innovation Photo showing climate zone maps based on ...

  12. Electroweak matching conditions for top pair production at threshold...

    Office of Scientific and Technical Information (OSTI)

    Electroweak matching conditions for top pair production at threshold Citation Details In-Document Search Title: Electroweak matching conditions for top pair production at threshold ...

  13. HVAC Cabinet Air Leakage Test Method - Building America Top Innovation...

    Energy Savers [EERE]

    HVAC Cabinet Air Leakage Test Method - Building America Top Innovation HVAC Cabinet Air Leakage Test Method - Building America Top Innovation While HVAC installers have improved ...

  14. Social Media and Messages that Matter - Top Tips and Tools |...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Social Media and Messages that Matter - Top Tips and Tools Better Buildings Residential Network Peer Exchange Call Series: Social Media and Messages that Matter - Top Tips and ...

  15. Top Green Energy Technologies Inc | Open Energy Information

    Open Energy Info (EERE)

    Green Energy Technologies Inc Jump to: navigation, search Name: Top Green Energy Technologies Inc Place: Jhunan, Taiwan Zip: 350 Sector: Solar Product: Top Green is a manufacturer...

  16. Tankless Gas Water Heater Performance - Building America Top...

    Energy Savers [EERE]

    Tankless Gas Water Heater Performance - Building America Top Innovation Tankless Gas Water Heater Performance - Building America Top Innovation This photo shows a hot water heater ...

  17. Water Management Guide - Building America Top Innovation | Department...

    Energy Savers [EERE]

    Water Management Guide - Building America Top Innovation Water Management Guide - Building America Top Innovation Cover of the EEBA Water Management Guide. As energy codes and ...

  18. Building America Top Innovations Hall of Fame Profile - Building...

    Energy Savers [EERE]

    Building America Top Innovations Hall of Fame Profile - Building Energy Optimization Analysis Method (BEopt) Building America Top Innovations Hall of Fame Profile - Building Energy...

  19. Deputy Energy Secretary Sherwood-Randall Highlights a Top Budget...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Deputy Energy Secretary Sherwood-Randall Highlights a Top Budget Priority in Texas Deputy Energy Secretary Sherwood-Randall Highlights a Top Budget Priority in Texas February 3,...

  20. Top 10 Vulnerabilities of Control Systems and Their Associated...

    Energy Savers [EERE]

    Top 10 Vulnerabilities of Control Systems and Their Associated Migitations (2006) Top 10 Vulnerabilities of Control Systems and Their Associated Migitations (2006) This document...

  1. TOP 10 VULNERABILITIES OF CONTROL SYSTEMS AND THEIR ASSOCIATED...

    Energy Savers [EERE]

    TOP 10 VULNERABILITIES OF CONTROL SYSTEMS AND THEIR ASSOCIATED MITIGATIONS TOP 10 VULNERABILITIES OF CONTROL SYSTEMS AND THEIR ASSOCIATED MITIGATIONS This document provides...

  2. Top of the World (Siemens) | Open Energy Information

    Open Energy Info (EERE)

    Siemens) Jump to: navigation, search Name Top of the World (Siemens) Facility Top of the World (Siemens) Sector Wind energy Facility Type Commercial Scale Wind Facility Status In...

  3. Final Reports on the Top Runner Target Product Standards (Japan...

    Open Energy Info (EERE)

    Reports on the Top Runner Target Product Standards (Japan) Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Final Reports on the Top Runner Target Product Standards...

  4. Sketching the pion's valence-quark generalised parton distribution

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

    Mezrag, C.; Chang, L.; Moutarde, H.; Roberts, C. D.; Rodrguez-Quintero, J.; Sabati, F.; Schmidt, S. M.

    2015-02-01

    In order to learn effectively from measurements of generalised parton distributions (GPDs), it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL) truncation of QCDs DysonSchwinger equations and exemplified via the pions valence dressed-quark GPD, Hv?(x, ?, t). Our analysis focuses primarily on ?=0, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting Hv?(x, ?=1, t)with the pions valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to definemorethe pions valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for Hv?(x, 0, t), expressed as the Radon transform of a single amplitude. Therewith we obtain results for Hv?(x, 0, t) and the associated impact-parameter dependent distribution, qv?(x, |b?|), which provide a qualitatively sound picture of the pions dressed-quark structure at a hadronic scale. We evolve the distributions to a scale ? = 2 GeV, so as to facilitate comparisons in future with results from experiment or other nonperturbative methods.less

  5. NREL Researcher is Top World Physicist

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

    is Top World Physicist For more information contact: Kerry Masson, (303) 275-4083 e:mail: kerry_masson@nrel.gov Golden, Colo., March 17, 1998 — Dr. Alex Zunger, Institute Research Fellow at the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL), has been ranked as one of the top physicists in the world by the Institute of Scientific Information (ISI). The standing is based on the number of times his research has been cited by fellow scientists. Of the 517,111

  6. TOP500 Supercomputers for November 2003

    SciTech Connect (OSTI)

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2003-11-16

    22nd Edition of TOP500 List of World s Fastest Supercomputers Released MANNHEIM, Germany; KNOXVILLE, Tenn.; BERKELEY, Calif. In what has become a much-anticipated event in the world of high-performance computing, the 22nd edition of the TOP500 list of the worlds fastest supercomputers was released today (November 16, 2003). The Earth Simulator supercomputer retains the number one position with its Linpack benchmark performance of 35.86 Tflop/s (''teraflops'' or trillions of calculations per second). It was built by NEC and installed last year at the Earth Simulator Center in Yokohama, Japan.

  7. Anisotropic flow of thermal photons as a quark-gluon plasma viscometer...

    Office of Scientific and Technical Information (OSTI)

    Anisotropic flow of thermal photons as a quark-gluon plasma viscometer Citation Details In-Document Search Title: Anisotropic flow of thermal photons as a quark-gluon plasma ...

  8. Photon emission from a momentum-anisotropic quark-gluon plasma...

    Office of Scientific and Technical Information (OSTI)

    Photon emission from a momentum-anisotropic quark-gluon plasma Citation Details In-Document Search Title: Photon emission from a momentum-anisotropic quark-gluon plasma Authors: ...

  9. Photon emission from a momentum-anisotropic quark-gluon plasma...

    Office of Scientific and Technical Information (OSTI)

    Photon emission from a momentum-anisotropic quark-gluon plasma Prev Next Title: Photon emission from a momentum-anisotropic quark-gluon plasma Authors: Shen, Chun ; Paquet, ...

  10. Quark04 Ray Stefanski Title Page A Select (SBL) Overview of Neutrino Experiments.

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

    4,2004 Quark04 Ray Stefanski Title Page A Select (SBL) Overview of Neutrino Experiments. Ray Stefanski for the MiniBooNE Collaboration Quark04 May 24,2004

  11. Suppression of the shear viscosity in a 'semi'-quark-gluon plasma...

    Office of Scientific and Technical Information (OSTI)

    Suppression of the shear viscosity in a 'semi'-quark-gluon plasma Citation Details In-Document Search Title: Suppression of the shear viscosity in a 'semi'-quark-gluon plasma We ...

  12. f{sub K}/f{sub {pi}} in full QCD with domain wall valence quarks...

    Office of Scientific and Technical Information (OSTI)

    fsub Kfsub pi in full QCD with domain wall valence quarks Citation Details In-Document Search Title: fsub Kfsub pi in full QCD with domain wall valence quarks We ...

  13. Vehicle Technologies Program: Goals, Strategies, and Top Accomplishments (Brochure)

    SciTech Connect (OSTI)

    Not Available

    2010-12-01

    Fact sheet describes the Vehicle Technologies Program and its goals, strategies and top accomplishments.

  14. Materials Technologies: Goals, Strategies, and Top Accomplishments (Brochure)

    SciTech Connect (OSTI)

    Not Available

    2010-08-01

    Document details the goals, strategies, and top accomplishments of DOE's Materials Technologies subprogram.

  15. Vehicle Technologies Program: Goals, Strategies, and Top Accomplishments

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (Brochure), Vehicle Technologies Program (VTP) | Department of Energy Program: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) Vehicle Technologies Program: Goals, Strategies, and Top Accomplishments (Brochure), Vehicle Technologies Program (VTP) PDF icon vtp_goals-strategies-accomp.pdf More Documents & Publications Advanced Combustion Engine R&D: Goals, Strategies, and Top Accomplishments Materials Technologies: Goals, Strategies, and Top

  16. Nucleation of quark matter in the PQM model

    SciTech Connect (OSTI)

    Mintz, Bruno W.; Stiele, Rainer; Schaffner-Bielich, Juergen; Ramos, Rudnei O.

    2013-03-25

    We use Langer's theory to calculate the surface tension of critical bubbles in a first-order quark-hadron phase transition at moderate and high baryon chemical potential, as predicted by the Polyakov-Quark-Meson (PQM) model at the mean-field level. We define an effective 4-dimensional order parameter, which is used to overestimate the surface tension of nucleating bubbles within the thin-wall approximation. We find relatively low values for the surface tension, {Sigma} Less-Than-Or-Equivalent-To 15MeV/fm{sup 2}. This implies that a metastable state, such as a supercooled quark-gluon plasma (QGP), quickly decays even in regions relatively close to the coexistence line of the phase diagram. Possible consequences for cosmology are briefly outlined.

  17. Gluons and the Quark Sea at High Energies: Distributions, Polarization, Tomography

    SciTech Connect (OSTI)

    Boer, Daniel; Diehl, Markus; Milner, Richard; Venugopalan, Raju; Vogelsang, Werner; Kaplan, David; Montgomery, Hugh; Vigdor, Steven; Accardi, A.; Aschenauer, E.C.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M.A.C.; Li, Ying-chuan; Marciano, W.; Marquet, C.; Sabatie, F.; Stratmann, M.; /more authors..

    2012-06-07

    This report on the science case for an Electron-Ion Collider (EIC) is the result of a ten-week program at the Institute for Nuclear Theory (INT) in Seattle (from September 13-November 19, 2010), motivated by the need to develop a strong case for the continued study of the QCD description of hadron structure in the coming decades. Hadron structure in the valence quark region will be studied extensively with the Jefferson Lab 12 GeV science program, the subject of an INT program the previous year. The focus of the INT program was on understanding the role of gluons and sea quarks, the important dynamical degrees of freedom describing hadron structure at high energies. Experimentally, the most direct and precise way to access the dynamical structure of hadrons and nuclei at high energies is with a high luminosity lepton probe in collider mode. An EIC with optimized detectors offers enormous potential as the next generation accelerator to address many of the most important, open questions about the fundamental structure of matter. The goal of the INT program, as captured in the writeups in this report, was to articulate these questions and to identify golden experiments that have the greatest potential to provide definitive answers to these questions. At resolution scales where quarks and gluons become manifest as degrees of freedom, the structure of the nucleon and of nuclei is intimately connected with unique features of QCD dynamics, such as confinement and the self-coupling of gluons. Information on hadron sub-structure in DIS is obtained in the form of 'snapshots' by the 'lepton microscope' of the dynamical many-body hadron system, over different momentum resolutions and energy scales. These femtoscopic snapshots, at the simplest level, provide distribution functions which are extracted over the largest accessible kinematic range to assemble fundamental dynamical insight into hadron and nuclear sub-structure. For the proton, the EIC would be the brightest femtoscope scale lepton-collider ever, exceeding the intensity of the HERA collider a thousand fold. HERA, with its center-of-mass (CM) energy of 320 GeV, was built to search for quark substructure. An EIC, with its scientific focus on studying QCD in the regime where the sea quarks and gluons dominate, would have a lower CM energy. In a staged EIC design, the CM energy will range from 50-70 GeV in stage I to approximately twice that for the full design. In addition to being the first lepton collider exploring the structure of polarized protons, an EIC will also be the first electron-nucleus collider, probing the gluon and sea quark structure of nuclei for the first time. Following the same structure as the scientific discussions at the INT, this report is organized around the following four major themes: (1) The spin and flavor structure of the proton; (2) Three dimensional structure of nucleons and nuclei in momentum and configuration space; (3) QCD matter in nuclei; and (4) Electroweak physics and the search for physics beyond the Standard Model. In this executive summary, we will briefly outline the outstanding physics questions in these areas and the suite of measurements that are available with an EIC to address these. The status of accelerator and detector designs is addressed at the end of the summary. Tables of golden measurements for each of the key science areas outlined are presented on page 12. In addition, each chapter in the report contains a comprehensive overview of the science topic addressed. Interested readers are encouraged to read these and the individual contributions for more details on the present status of EIC science.

  18. Exclusive B{yields}{rho}l{sup +}l{sup -} decay in the standard model with fourth-generation quarks

    SciTech Connect (OSTI)

    Zeynali, K.; Bashiry, V.

    2008-08-01

    We investigate the influence of the fourth generation of quarks on the branching ratio, the CP asymmetry, and the polarization asymmetries in B{yields}{rho}l{sup +}l{sup -} decay. Taking |V{sub t{sup '}}{sub d}V{sub t{sup '}}{sub b}|{approx}0.001 with phase about 10 deg., which is consistent with the sin2{phi}{sub 1} of the Cabibbo-Kobayashi-Maskawa matrix and the B{sub d} mixing parameter {delta}m{sub B{sub d}}, we obtain that for both ({mu},{tau}) channels the branching ratio is increased and the magnitude of CP asymmetry and polarization asymmetries decreased by the mass and mixing parameters of the 4th generation of quarks. These results can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation of quarks (t{sup '},b{sup '}) via its indirect manifestations in loop diagrams.

  19. 2015's Top Five Blog Posts

    Broader source: Energy.gov [DOE]

    Here on the EERE Blog, we tell other stories related to the Energy Department’s efforts to develop and deliver market solutions for energy saving-homes, buildings, and manufacturing; sustainable transportation; and renewable electricity generation. Here are our top five blog posts for 2015.

  20. G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure |

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

    Jefferson Lab G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure June 17, 2005 In research performed at the Department of Energy's Jefferson Lab, nuclear physicists have found that strange quarks do contribute to the structure of the proton. This result indicates that, just as previous experiments have hinted, strange quarks in the proton's quark-gluon sea contribute to a proton's properties. The result comes from work performed by the G-Zero collaboration, an international

  1. Nuclear-matter--quark-matter phase diagram with strangeness

    SciTech Connect (OSTI)

    Barz, H. W.; Friman, B. L.; Knoll, J.; Schulz, H.

    1989-07-01

    A phenomenological equation of state of strongly interacting matter, including strange degrees of freedom, is presented. It is shown that the hyperon and kaon interactions must be included, in order to obtain a reasonable description of the deconfinement transition at high baryon densities. The consequences of kaon condensation on the nuclear-matter--quark-matter phase diagram are explored. The relative particle abundances obtained in an isentropic expansion of a blob of quark-gluon plasma are presented for different initial conditions. Implications for ultrarelativistic heavy-ion collisions are briefly discussed.

  2. Building America Top Innovations Hall of Fame Profile - Building

    Energy Savers [EERE]

    America's Top Innovations Propel the Home Building Industry toward Higher Performance | Department of Energy Top Innovations Hall of Fame Profile - Building America's Top Innovations Propel the Home Building Industry toward Higher Performance Building America Top Innovations Hall of Fame Profile - Building America's Top Innovations Propel the Home Building Industry toward Higher Performance This Building America Innovations profile describes the concept for the U.S. Department of Energy

  3. Search for New Bottomlike Quark Pair Decays Q Q-Bar to (T W- ) (T-Bar W -) in Same-Charge Dilepton Events

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; /more authors..

    2012-04-02

    We report the most restrictive direct limits on masses of fourth-generation down-type quarks b{prime}, and quark-like composite fermions (B or T{sub 5/3}), decaying promptly to tW{sup {-+}}. We search for a significant excess of events with two same-charge leptons (e, {mu}), several hadronic jets, and missing transverse energy. An analysis of data from p{bar p} collisions with an integrated luminosity of 2.7 fb{sup -1} collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits m{sub b{prime}}, m{sub B} > 338 GeV/c{sup 2} and m{sub T{sub 5/3}} > 365 GeV/c{sup 2} at 95% confidence level.

  4. Forward-Backward Asymmetry at High Mass in $t\\bar{t}$ Production in $p\\bar{p}$ Collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Eppig, Andrew; /Michigan U.

    2011-04-01

    Current understanding of particle physics postulates that there are 17 fundamental particles that interact via four fundamental forces - gravity, the strong force, the weak force, and the electromagnetic force. These fundamental particles can be classified by their spins into bosons, which are the force-carrying particles with integer spins, and fermions, which have half-integer spins. Fermions can be further divided into quarks and leptons. The particles and three of the four forces - all but gravity - are described by the Standard Model, a local SU(3) x SU(2) x U(1) gauge theory. Electromagnetic and weak interactions as described by Electroweak Theory or Quantum Electrodynamics, SU(2) x U(1). Strong interactions are described by Quantum Chromodynamics or QCD, SU(3). Fermions are grouped into three generations as shown in Table 1.1. Each generation consists of a leptonic doublet containing a charged and a neutral lepton and a weak isospin doublet containing two quarks. The first generation, containing the electron, the electron neutrino, the up quark, and the down quark, is the lightest generation and is thus the most frequently found in nature. The second generation contains the muon, the muon neutrino, the strange quark, and the charm quark. The third generation contains the tau, the tau neutrino, the bottom quark, and the top quark.

  5. Application of the Principle of Maximum Conformality to Top-Pair Production

    SciTech Connect (OSTI)

    Brodsky, Stanley J.; Wu, Xing-Gang; /SLAC /Chongqing U.

    2013-05-13

    A major contribution to the uncertainty of finite-order perturbative QCD predictions is the perceived ambiguity in setting the renormalization scale {mu}{sub r}. For example, by using the conventional way of setting {mu}{sub r} {element_of} [m{sub t}/2, 2m{sub t}], one obtains the total t{bar t} production cross-section {sigma}{sub t{bar t}} with the uncertainty {Delta}{sigma}{sub t{bar t}}/{sigma}{sub t{bar t}} {approx} (+3%/-4%) at the Tevatron and LHC even for the present NNLO level. The Principle of Maximum Conformality (PMC) eliminates the renormalization scale ambiguity in precision tests of Abelian QED and non-Abelian QCD theories. By using the PMC, all nonconformal {l_brace}{beta}{sub i}{r_brace}-terms in the perturbative expansion series are summed into the running coupling constant, and the resulting scale-fixed predictions are independent of the renormalization scheme. The correct scale-displacement between the arguments of different renormalization schemes is automatically set, and the number of active flavors n{sub f} in the {l_brace}{beta}{sub i}{r_brace}-function is correctly determined. The PMC is consistent with the renormalization group property that a physical result is independent of the renormalization scheme and the choice of the initial renormalization scale {mu}{sub r}{sup init}. The PMC scale {mu}{sub r}{sup PMC} is unambiguous at finite order. Any residual dependence on {mu}{sub r}{sup init} for a finite-order calculation will be highly suppressed since the unknown higher-order {l_brace}{beta}{sub i}{r_brace}-terms will be absorbed into the PMC scales higher-order perturbative terms. We find that such renormalization group invariance can be satisfied to high accuracy for {sigma}{sub t{bar t}} at the NNLO level. In this paper we apply PMC scale-setting to predict the t{bar t} cross-section {sigma}{sub t{bar t}} at the Tevatron and LHC colliders. It is found that {sigma}{sub t{bar t}} remains almost unchanged by varying {mu}{sub r}{sup init} within the region of [m{sub t}/4, 4m{sub t}]. The convergence of the expansion series is greatly improved. For the (q{bar q})-channel, which is dominant at the Tevatron, its NLO PMC scale is much smaller than the top-quark mass in the small x-region, and thus its NLO cross-section is increased by about a factor of two. In the case of the (gg)-channel, which is dominant at the LHC, its NLO PMC scale slightly increases with the subprocess collision energy {radical}s, but it is still smaller than m{sub t} for {radical} {approx}< 1 TeV, and the resulting NLO cross-section is increased by {approx}20%. As a result, a larger {sigma}{sub t{bar t}} is obtained in comparison to the conventional scale-setting method, which agrees well with the present Tevatron and LHC data. More explicitly, by setting m{sub t} = 172.9 {+-} 1.1 GeV, we predict {sigma}{sub Tevatron, 1.96 TeV} = 7.626{sub -0.257}{sup +0.265} pb, {sigma}{sub LHC, 7 TeV} = 171.8{sub -5.6}{sup +5.8} pb and {sigma}{sub LHC, 14 TeV} = 941.3{sub -26.5}{sup +28.4} pb.

  6. Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

    SciTech Connect (OSTI)

    Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; Baker, O. K.; Benmouna, N.; Bertoncini, C.; Blok, H. P.; Boeglin, W. U.; Bosted, P. E.; Breuer, H.; Christy, M. E.; Connell, S. H.; Cui, Y.; Dalton, M. M.; Danagoulian, S.; Day, D.; Dunne, J. A.; Dutta, D.; El Khayari, N.; Fenker, H. C.; Frolov, V. V.; Gan, L.; Gaskell, D.; Hafidi, K.; Hinton, W.; Holt, R. J.; Horn, T.; Huber, G. M.; Hungerford, E.; Jiang, X.; Jones, M.; Joo, K.; Kalantarians, N.; Kelly, J. J.; Keppel, C. E.; Kubarovsky, V.; Li, Y.; Liang, Y.; Mack, D.; Malace, S. P.; Markowitz, P.; McGrath, E.; McKee, P.; Meekins, D. G.; Mkrtchyan, A.; Moziak, B.; Niculescu, G.; Niculescu, I.; Opper, A. K.; Ostapenko, T.; Reimer, P. E.; Reinhold, J.; Roche, J.; Rock, S. E.; Schulte, E.; Segbefia, E.; Smith, C.; Smith, G. R.; Stoler, P.; Tang, L.; Ungaro, M.; Uzzle, A.; Vidakovic, S.; Villano, A.; Vulcan, W. F.; Wang, M.; Warren, G.; Wesselmann, F. R.; Wojtsekhowski, B.; Wood, S. A.; Xu, C.; Yuan, L.; Zheng, X.

    2012-01-01

    A large set of cross sections for semi-inclusive electroproduction of charged pions (?) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W', is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark ? pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for ?+ and ?-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.

  7. Inclusive search for a vector-like T quark with charge $\\frac{2}{3}$ in pp collisions at $\\sqrt{s}$ = 8 TeV

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

    Chatrchyan, Serguei

    2014-01-08

    A search is performed for a massive new vector-like quark T, with charge 2/3, that is pair produced together with its antiparticle in proton-proton collisions. The data were collected by the CMS experiment at the Large Hadron Collider in 2012 at sqrt(s) = 8 TeV and correspond to an integrated luminosity of 19.5 inverse femtobarns. The T quark is assumed to decay into three different final states, bW, tZ, and tH. The search is carried out using events with at least one isolated lepton. No deviations from standard model expectations are observed, and lower limits are set on the Tmore »quark mass at 95% confidence level. The lower limit lies between 687 and 782 GeV for all possible values of the branching fractions into the three different final states assuming strong production. These limits are the most stringent constraints to date on the existence of such a quark.« less

  8. Exploring Stratocumulus Cloud-Top Entrainment Processes

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

    Stratocumulus Cloud-Top Entrainment Processes and Parameterizations by Using Doppler For original submission and image(s), see ARM Research Highlights http://www.arm.gov/science/highlights/ Research Highlight Stratocumulus clouds are a particularly important component of the Earth's climate system due to their large impact on the radiation budget. But the parameterization of entrainment in these clouds is yet to be fully resolved, which leads to uncertainties in numerical model forecasts ranging

  9. NREL'S Zunger Receives Top Scientific Honors

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

    Top Scientific Honors For more information contact: Gary Schmitz, 303-275-4050 email: Gary Schmitz Golden, Colo., Nov. 29, 2000 - Alex Zunger, a physicist and research fellow at the U.S. Department of Energy's National Renewable Energy Laboratory, has been named the 2001 recipient of the prestigious Rahman Award by the American Physical Society (APS). The award from the APS is bestowed once annually to an individual for "outstanding achievement in computational physics research."

  10. JLab Cluster Tops 100 Teraflops | Jefferson Lab

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

    JLab Cluster Tops 100 Teraflops NEWPORT NEWS, VA, Oct. 14 - The fastest computer system in Hampton Roads has booted up with more than 100 Teraflops of processing power. Located at the Department of Energy's Thomas Jefferson National Accelerator Facility, the cluster computer system was recently upgraded with video game components to assist scientists in modeling the smallest bits of matter in the universe. "Our resources crossed 100 Teraflops of sustained processing while running a science

  11. TOP500 | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    TOP500 | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile Preventing Proliferation Powering the Nuclear Navy Emergency Response Recapitalizing Our Infrastructure Countering Nuclear Terrorism About Our Programs Our History Who We Are Our Leadership Our Locations Budget Our Operations Library Bios Congressional Testimony Fact Sheets Newsletters Press Releases Photo Gallery Jobs Apply for Our Jobs Our Jobs Working at NNSA Blog Home /

  12. Satellite Television Industry Meeting Regarding DOE Set-Top Box...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Satellite Television Industry Meeting Regarding DOE Set-Top Box Rulemaking Satellite Television Industry Meeting Regarding DOE Set-Top Box Rulemaking On April 3, 2012 at 11:00 AM,...

  13. Top of the World (GE) | Open Energy Information

    Open Energy Info (EERE)

    GE) Jump to: navigation, search Name Top of the World (GE) Facility Top of the World (GE) Sector Wind energy Facility Type Commercial Scale Wind Facility Status In Service Owner...

  14. Programs and Contractors - Top Tips for Successful Relationships...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Programs and Contractors - Top Tips for Successful Relationships (101) Programs and Contractors - Top Tips for Successful Relationships (101) October 22, 2015 1:00PM to 2:30PM...

  15. Effective Guidance and Tools - Building America Top Innovations |

    Energy Savers [EERE]

    Department of Energy Effective Guidance and Tools - Building America Top Innovations Effective Guidance and Tools - Building America Top Innovations August 25, 2014 - 11:00am Addthis Effective Guidance and Tools - Building America Top Innovations Top Innovations in this category include tools, software, and guides that have significantly influenced or changed design or construction practices. These include practical, hands-on resources as well as technical energy analysis tools. High

  16. America's Next Top Energy Innovator Challenge | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Science & Innovation » Innovation » America's Next Top Energy Innovator » America's Next Top Energy Innovator Challenge America's Next Top Energy Innovator Challenge The America's Next Top Energy Innovator Challenge, a part of the Startup America initiative, made it easier for start-ups to use inventions and technology developed at the U.S. Department of Energy's 17 National Laboratories and the Y-12 National Security Complex. The companies highlighted below signed option agreements

  17. Announcing the "Top 10" List of Green Utility Leaders

    Broader source: Energy.gov [DOE]

    Find out if your utility made the National Renewable Energy Laboratory's list of top green power programs.

  18. LANL announces Top 10 science & technology developments of 2010

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

    2010 top 10 science & technology developments LANL announces Top 10 science & technology developments of 2010 Top 10 developments based on major programmatic milestones, strategic potential, scholarly accounts, and associated news coverage. December 20, 2010 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to

  19. Advanced Technologies and Practices - Building America Top Innovations |

    Energy Savers [EERE]

    Department of Energy Advanced Technologies and Practices - Building America Top Innovations Advanced Technologies and Practices - Building America Top Innovations July 16, 2014 - 4:04pm Addthis Advanced Technologies and Practices - Building America Top Innovations Top Innovations in this category encompass research in specific technologies and construction practices that improve the building envelope; heating, ventilation, and air conditioning (HVAC); water heating components; and indoor air

  20. America's Next Top Energy Innovator Challenge | Department of Energy

    Energy Savers [EERE]

    Science & Innovation » Innovation » America's Next Top Energy Innovator » America's Next Top Energy Innovator Challenge America's Next Top Energy Innovator Challenge The America's Next Top Energy Innovator Challenge, a part of the Startup America initiative, made it easier for start-ups to use inventions and technology developed at the U.S. Department of Energy's 17 National Laboratories and the Y-12 National Security Complex. The companies highlighted below signed option agreements

  1. America Chooses the Next Top Energy Innovator | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    America Chooses the Next Top Energy Innovator America Chooses the Next Top Energy Innovator February 10, 2012 - 1:00pm Addthis The America’s Next Top Energy Innovator Challenge makes inventions and technologies developed at the U.S. Department of Energy’s 17 National Laboratories and the Y-12 National Security Complex available to innovative startups. | Photo courtesy of Lawrence Berkeley National Laboratory. The America's Next Top Energy Innovator Challenge makes inventions and

  2. Doe's Race to the top initiative

    Broader source: Energy.gov (indexed) [DOE]

    Race to the Top Initiative Recommendations of the EAC Working Group June 5, 2013 EAC Working Group * Chair: Sonny Popowsky * Vice-Chair: Bob Curry * Working Group Members: Ralph Cavanagh, Sue Kelly, Paul Centolella, Dian Grueneich, Val Jensen, Paul Hudson, Phyllis Reha, Ralph Masiello, Mike Weedall RAP Staff - Janine Migden-Ostrander 2 President's State of the Union Message February 12, 2013 "I'm also issuing a new goal for America: Let's cut in half the energy wasted by our homes and

  3. NLO evolution of 3-quark Wilson loop operator

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

    Balitsky, I.; Grabovsky, A. V.

    2015-01-07

    It is well known that high-energy scattering of a meson from some hadronic target can be described by the interaction of that target with a color dipole formed by two Wilson lines corresponding to fast quark-antiquark pair. Moreover, the energy dependence of the scattering amplitude is governed by the evolution equation of this color dipole with respect to rapidity. Similarly, the energy dependence of scattering of a baryon can be described in terms of evolution of a three-Wilson-lines operator with respect to the rapidity of the Wilson lines. We calculate the evolution of the 3-quark Wilson loop operator in themore » next-to-leading order (NLO) and present a quasi-conformal evolution equation for a composite 3-Wilson-lines operator. Thus we also obtain the linearized version of that evolution equation describing the amplitude of the odderon exchange at high energies.« less

  4. Quantum simulations of strongly coupled quark-gluon plasma

    SciTech Connect (OSTI)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2011-09-15

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the model developed by B.A. Gelman, E.V. Shuryak, and I. Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective string-like forces and turn out to be colorless. At the temperature as large as twice the critical one no bound states are observed. Quantum effects turned out to be of prime importance in these simulations.

  5. The physics of hot and dense quark-gluon matter

    SciTech Connect (OSTI)

    Kharzeev, Dmitri E

    2012-05-10

    This technical report describes the work done under the DOE grant DE-FG-88ER41723 (final award number DE-SC0005645), "The physics of hot and dense quark-gluon matter", during the year of 12/01/2010 through 11/30/2011. As planned in the proposal, the performed research focused along two main thrusts: 1) topological effects in hot quark-gluon matter and 2) phenomenology of relativistic heavy ion collisions. The results of research are presented in 12 papers published in reputable refereed journals (Physical Review Letters, Physical Review, Physics Letters and Nuclear Physics). All of the performed research is directly related to the experimental programs of DOE, especially at the Relativistic Heavy Ion Collider. Much of it also has broader interdisciplinary implications - for example, the work on the non-dissipative chiral magnetic current is directly relevant for quantum computing. The attached report describes the performed work in detail.

  6. Search for the Production of Scalar Bottom Quarks in $p \\bar {p} $ collisions at $\\sqrt{s} $ = 1.96 TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.

    2010-05-01

    We report on a search for direct scalar bottom quark (sbottom) pair production in p{bar p} collisions at {radical}s = 1.96 TeV, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a b quark. The study uses a CDF Run II data sample corresponding to 2.65 fb{sup -1} of integrated luminosity. The data are in agreement with the standard model. In an R-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below 70 GeV/c{sup 2}, sbottom masses up to 230 GeV/c{sup 2} are excluded at 95% confidence level.

  7. Partial Quark-Lepton Universality and Neutrino CP Violation

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

    Liao, Jiajun; Marfatia, D.; Whisnant, K.

    2015-01-01

    We smore » tudy a model with partial quark-lepton universality that can naturally arise in grand unified theories. We find that constraints on the model can be reduced to a single condition on the Dirac CP phase δ in the neutrino sector. Using our current knowledge of the CKM and PMNS mixing matrices, we predict - 32 . 4 ° ≤ δ ≤ 32 . 0 ° at 2 σ .« less

  8. Two-component quark-gluon plasma in stringy models

    SciTech Connect (OSTI)

    Verschelde, H.; Zakharov, V. I.

    2011-05-23

    The two-component liquid model reproduces the basic properties of the quark-gluon plasma as observed in heavy-ion collisions. The key dynamic element of the model is existence of a light scalar. We argue that existence of such a scalar is a generic feature of the stringy models of quantum chromodynamics. The lattice data provides evidence for a condensed, three-dimensional scalar field as well. We outline a possible crucial check of the model on the lattice.

  9. Classical strongly coupled quark-gluon plasma. V. Structure factors

    SciTech Connect (OSTI)

    Cho, Sungtae; Zahed, Ismail

    2010-10-15

    We show that the classical and strongly coupled quark-gluon plasma is characterized by a multiple of structure factors that obey generalized Orstein-Zernicke equations. We use the canonical partition function and its associated density functional to derive analytical equations for the density and charge monopole structure factors for arbitrary values of {Gamma}=V/K, the ratio of the mean potential to the Coulomb energy. The results are compared with SU(2) molecular dynamics simulations.

  10. Quantum simulations of strongly coupled quark-gluon plasma

    SciTech Connect (OSTI)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2012-06-15

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasi-particles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the classical molecular dynamics by Gelman, Shuryak, and Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state. The results indicate that the QGP reveals liquid-like rather than gaslike properties. Quantum effects turned out to be of prime importance in these simulations.

  11. Los Alamos National Laboratory top science news of 2012

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

    Los Alamos National Laboratory top science news of 2012 Los Alamos National Laboratory top science news of 2012 Top science stories for the year traveled from the canyons of Mars to the high desert forests of New Mexico, from cosmic particles to the structure of proteins and enzymes. December 20, 2012 Top science stories for the year traveled from the canyons of Mars to the high desert forests of New Mexico, from cosmic particles to the structure of proteins and enzymes. Top science stories for

  12. Top 100 Oil and Gas Fields of 2009

    U.S. Energy Information Administration (EIA) Indexed Site

    Top 100 Oil and Gas Fields of 2009 Introduction This supplement to the Energy Information Administration's summary of U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves, 2009 ranks the United States' largest oil and gas fields by their estimated 2009 proved reserves. The Top 100's Share of U.S. Proved Reserves in 2009 The Top 100 oil fields and Top 100 gas fields each accounted for about 60 percent of the respective total proved reserves of the United States. The Top 100 oil

  13. Numerical simulation of the hydrodynamical combustion to strange quark matter

    SciTech Connect (OSTI)

    Niebergal, Brian; Ouyed, Rachid; Jaikumar, Prashanth

    2010-12-15

    We present results from a numerical solution to the burning of neutron matter inside a cold neutron star into stable u,d,s quark matter. Our method solves hydrodynamical flow equations in one dimension with neutrino emission from weak equilibrating reactions, and strange quark diffusion across the burning front. We also include entropy change from heat released in forming the stable quark phase. Our numerical results suggest burning front laminar speeds of 0.002-0.04 times the speed of light, much faster than previous estimates derived using only a reactive-diffusive description. Analytic solutions to hydrodynamical jump conditions with a temperature-dependent equation of state agree very well with our numerical findings for fluid velocities. The most important effect of neutrino cooling is that the conversion front stalls at lower density (below {approx_equal}2 times saturation density). In a two-dimensional setting, such rapid speeds and neutrino cooling may allow for a flame wrinkle instability to develop, possibly leading to detonation.

  14. Charm and strange quark masses and f D s from overlap fermions...

    Office of Scientific and Technical Information (OSTI)

    This content will become publicly available on August 25, 2016 Title: Charm and strange ... become publicly available on August 25, 2016 Publisher's Version of Record 10.1103...

  15. Nonfactorization of four-quark condensates at low energies within chiral perturbation theory

    SciTech Connect (OSTI)

    Gomez Nicola, A.; Pelaez, J. R.; Ruiz de Elvira, J.

    2010-10-01

    Four-quark correlators and the factorization hypothesis are analyzed in the meson sector within chiral perturbation theory. We define the four-quark condensate as lim{sub x{yields}0}, which is equivalent to other definitions commonly used in the literature. Factorization of the four-quark condensate holds to leading and next to leading order. However, at next to next to leading order, a term with a nontrivial space-time dependence in the four-quark correlator yields a divergent four-quark condensate, whereas the two-quark condensate and the scalar susceptibility are finite. Such a nonfactorization term vanishes only in the chiral limit. We also comment on how factorization still holds in the large N{sub c} limit, provided such a limit is taken before renormalization.

  16. Viscosity and dilepton production of a chemically equilibrating quark-gluon plasma at finite baryon density

    SciTech Connect (OSTI)

    Guan Nana; Li Jianwei; He Zejun; Long Jiali; Cai Xiangzhou; Ma Yugang; Shen Wenqing

    2009-07-15

    By considering the effect of shear viscosity we have investigated the evolution of a chemically equilibrating quark-gluon plasma at finite baryon density. Based on the evolution of the system we have performed a complete calculation for the dilepton production from the following processes: qq{yields}ll, qq{yields}gll, Compton-like scattering (qg{yields}qll,qg{yields}qll), gluon fusion (gg{yields}cc), annihilation (qq{yields}cc), as well as the multiple scattering of quarks. We have found that quark-antiquark annihilation, Compton-like scatterring, gluon fusion, and multiple scattering of quarks give important contributions. Moreover, we have also found that the dilepton yield is an increasing function of the initial quark chemical potential, and the increase of the quark phase lifetime because of the viscosity also obviously raises the dilepton yield.

  17. Heavy Quarks, QCD, and Effective Field Theory (Technical Report) | SciTech

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

    Connect Heavy Quarks, QCD, and Effective Field Theory Citation Details In-Document Search Title: Heavy Quarks, QCD, and Effective Field Theory The research supported by this OJI award is in the area of heavy quark and quarkonium production, especially the application Soft-Collinear E#11;ective Theory (SCET) to the hadronic production of quarkonia. SCET is an e#11;ffective theory which allows one to derive factorization theorems and perform all order resummations for QCD processes.

  18. Doubly heavy baryons and quark-diquark symmetry in quenched and partially

    Office of Scientific and Technical Information (OSTI)

    quenched chiral perturbation theory (Journal Article) | SciTech Connect Doubly heavy baryons and quark-diquark symmetry in quenched and partially quenched chiral perturbation theory Citation Details In-Document Search Title: Doubly heavy baryons and quark-diquark symmetry in quenched and partially quenched chiral perturbation theory We extend the chiral Lagrangian with heavy quark-diquark symmetry to quenched and partially quenched theories. These theories are used to derive formulae for the

  19. Structure functions and pair correlations of the quark-gluon plasma

    SciTech Connect (OSTI)

    Thoma, Markus H.

    2005-11-01

    Recent experiments at RHIC and theoretical considerations indicate that the quark-gluon plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the quark-gluon plasma are presented as well as perturbative results. These definitions might be useful for verifying the quark-gluon-plasma liquid in QCD lattice calculations.

  20. Two-color quark matter: U(1){sub A} restoration, superfluidity, and

    Office of Scientific and Technical Information (OSTI)

    quarkyonic phase (Journal Article) | SciTech Connect Two-color quark matter: U(1){sub A} restoration, superfluidity, and quarkyonic phase Citation Details In-Document Search Title: Two-color quark matter: U(1){sub A} restoration, superfluidity, and quarkyonic phase We discuss the phase structure of quantum chromodynamics (QCD) with two colors and two flavors of light quarks. This is motivated by the increasing interest in the QCD phase diagram as follows: (1) The QCD critical point search