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Title: Measurement of the Diphoton Differential Cross Section in p anti-p Collisions at √s = 1.96-TeV

Abstract

The diphoton differential cross-section as a function of mass up to 300 GeV/c 2, q T up to 100 GeV/c, and opening angle over a range of 0 to π radians is measured. The measurement is performed using 1046.19 pb -1 of data collected at Fermi National Accelerator Laboratory using the D0 detector. This analysis considers all direct diphoton states but attempts to suppress contributions due to fragmentation.

Authors:
 [1]
+ Show Author Affiliations
  1. Michigan State Univ., East Lansing, MI (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
935245
Report Number(s):
FERMILAB-THESIS-2007-62
TRN: US0804164
DOE Contract Number:
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DIFFERENTIAL CROSS SECTIONS; FERMILAB ACCELERATOR; FRAGMENTATION; OPENINGS; Experiment-HEP

Citation Formats

Dyer, Joshua Marc. Measurement of the Diphoton Differential Cross Section in p anti-p Collisions at √s = 1.96-TeV. United States: N. p., 2007. Web. doi:10.2172/935245.
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Dyer, Joshua Marc. Measurement of the Diphoton Differential Cross Section in p anti-p Collisions at √s = 1.96-TeV. United States. doi:10.2172/935245.
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Dyer, Joshua Marc. Mon . "Measurement of the Diphoton Differential Cross Section in p anti-p Collisions at √s = 1.96-TeV". United States. doi:10.2172/935245. https://www.osti.gov/servlets/purl/935245.
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@article{osti_935245,
title = {Measurement of the Diphoton Differential Cross Section in p anti-p Collisions at √s = 1.96-TeV},
author = {Dyer, Joshua Marc},
abstractNote = {The diphoton differential cross-section as a function of mass up to 300 GeV/c2, qT up to 100 GeV/c, and opening angle over a range of 0 to π radians is measured. The measurement is performed using 1046.19 pb-1 of data collected at Fermi National Accelerator Laboratory using the D0 detector. This analysis considers all direct diphoton states but attempts to suppress contributions due to fragmentation.},
doi = {10.2172/935245},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
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Thesis/Dissertation:
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DOI:  10.2172/935245
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  • This thesis presents the measurement of prompt diphoton production rate in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV using the upgraded Collider Detector at Fermilab (CDF II). This process deserves some attention for the following reasons. The H → γγ decay mode is an important channel for the Standard Model (SM) Higgs boson searches in the low mass region (M H < 130 GeV) at the forth coming LHC. In many models involving physics beyond the SM, cascade decays of heavy new particles generate a γγ signature. Some examples are supersymmetry with a light gravitino, radiative decays tomore » a higgsino-LSP and models with large symmetry groups. The QCD production of prompt photon pairs with large invariant mass is the irreducible background to these searches. The rate is huge and requires to be quantitatively evaluated prior to any of the possible discoveries. In a hadronic collider environment such as LHC, prompt photon signals are contaminated by the production of neutral mesons which decay to multiple collinear photons. The experience of classifying background of neutral meson is very important. The process can be used to test the Next-to-Leading Order (NLO) calculation of Quantum Chromodynamics (QCD). The 4-momentum of particles in the di-photon final state can be precisely determined due to the fine energy resolution of the electromagnetic calorimeters. The imbalance in the transverse momentum of the two photons reflects the transverse motion of the colliding partons. At collider energies, most of the transverse momentum of the incoming partons can be attributed to multiple soft gluon emissions prior to the collision, of which the effect to di-photon production can be resummed by Collins-Soper-Sterman (CSS) formalism. The Tevatron data can be used to test the resummation formalisms. They have used 207 pb -1 of data collected by CDF II detector during the February 2002 to September 2003 running period to study the diphoton QCD production, and compared with next-to-leading order predictions. The background is subtracted using a statistical method based on the difference between the EM showers initiated by photons and by the backgrounds. The cross sections are measured as a function of diphoton mass, diphoton system transverse momentum and azimuthal angle between the two photons. The results are found to be consistent with perturbative QCD predictions.« less

  • We measure the production cross section of tmore » $$\bar{t}$$ events in p$$\bar{p}$$ collisions at √s = 1.96 TeV. The data was collected by the CDF experiment in Run 2 of the Tevatron accelerator at the Fermi National Accelerator Laboratory between 2002 and 2007. 1.7 fb -1 of data was recorded during this time period. We reconstruct t$$\bar{t}$$ events in the lepton+jets channel, whereby one W boson - resulting from the decay of the top quark pairs - decays leptonically and the other hadronically. The dominant background to this process is the production of W bosons in association with multiple jets. To distinguish t$$\bar{t}$$ from background, we identify soft electrons from the semileptonic decay of heavy flavor jets produced in t$$\bar{t}$$ events. We measure a cross section of σ $$\bar{p}$$ = 7.8 ± 2.4(stat) ± 1.6(syst) ± 0.5(lumi).« less

  • The direct observation of the top quark was first achieved at the Tevatron proton anti-proton collider at Fermilab. This discovery completed the third generation quark sector where the top quark is expected to accompany the bottom quark in the weak isospin doublet. This dissertation discusses the experimental verification of the production cross section as predicted by the Standard Model. A measurement of the tmore » $$\bar{t}$$ production cross section using 107.9 pb -1 of p$$\bar{p}$$ collisions at √s = 1.96 TeV collected with the Collider Detector at Fermilab between March of 2003 and June of 2003 is presented. The measurement focuses on the t$$\bar{t}$$ production in the ''lepton plus jets'' final state in which one of the W bosons from the t$$\bar{t}$$ decay subsequently decays leptonically to an electron or a muon, and the other decays hadronically. The B-tagging technique which utilizes the precision silicon detector tracking is used to enhance the signal for t$$\bar{t}$$ events relative to the background through identification of the bottom quark from its measurable lifetime. The t$$\bar{t}$$ production cross section is measured to be σ t$$\bar{t}$$ = 4.5 ± 1.4(stat) ± 0.8(sys) pb.« less

  • A cross section measurement for the production of W +W - is performed. Differential measurements are reported as a function of jet multiplicity and transverse energy. The inclusive cross section is measured to be σ(pmore » $$\bar{p}$$→W+W -+X=14.0±0.6(stat)$$+1.2\atop{-1.0}$$(syst)±0.8(lumi)±0.8(lumi) pb, consistent with the Standard Model prediction. Additionally, a search for the Higgs boson is performed in the final state of W+W - with two or more associated jets. Limits on the production cross section are set at the 95%95% confidence level, and combined with limits from related analyses. Both analyses use data collected by the CDF II detector from 9.7fb -1 of luminosity.« less

  • The subject of this thesis is the measurement of the rate at which a top-antitop quark pair is produced in pp collisions at a center of mass energy of ps = 1:96 TeV. The data are collected with the D detector, a multi-purpose detector operating at the Fermilab Tevatron collider during Run II. A measurement of the top quark pair (tmore » $$\bar{t}$$) production cross section ( σ t$$\bar{t}$$) in p$$\bar{p}$$ collisions at a center of mass energy of 1.96 TeV is presented. The measurement is based on data recorded by the D0 Detector at the Fermilab Tevatron Collider, and preselected in the e+jets (366 pb -1) and μ+jets (363 pb -1) channels. The cross section is extracted by applying a lifetime-tagging technique to the data, and yields σ t$$\bar{t}$$ = 6.96$$+1.07\atop{-0.98}$$(stat + syst) ± 0.45(lumi) pb; for a top quark mass m t =175 GeV, in good agreement with the Standard Model prediction.« less