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Title: Precision Determination of the Top Quark Mass

Abstract

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}.

Authors:
;
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
910191
Report Number(s):
FERMILAB-CONF-07-138-E
arXiv eprint number arXiv:0705.3910; TRN: US0704113
DOE Contract Number:
AC02-07CH11359
Resource Type:
Conference
Resource Relation:
Conference: To appear in the proceedings of 21st Les Rencontres de Physique de la Vallee d'Aoste, La Thuile, Aosta, Italy, 4-10 Mar 2007
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; DECAY; FERMILAB COLLIDER DETECTOR; FERMILAB TEVATRON; T QUARKS; Experiment-HEP

Citation Formats

Movilla Fernandez, Pedro A., and /LBL, Berkeley. Precision Determination of the Top Quark Mass. United States: N. p., 2007. Web.
Movilla Fernandez, Pedro A., & /LBL, Berkeley. Precision Determination of the Top Quark Mass. United States.
Movilla Fernandez, Pedro A., and /LBL, Berkeley. Tue . "Precision Determination of the Top Quark Mass". United States. doi:. https://www.osti.gov/servlets/purl/910191.
@article{osti_910191,
title = {Precision Determination of the Top Quark Mass},
author = {Movilla Fernandez, Pedro A. and /LBL, Berkeley},
abstractNote = {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}.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}

Conference:
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  • We present recent measurements of the top quark mass using events collected at the CDF and D0 detectors from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. These analyses are performed using events consistent with the decay channel t{bar t} {yields} {bar b}{ell}{sup -}{bar v}{sub {ell}}b{ell}' + v'{sub {ell}}, or the dilepton channel. 230-360 pb{sup -1} of data are used.
  • We report precision measurements of the top quark mass using events collected by the D0 and CDF II detectors from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. Measurements are presented in multiple decay channels. In addition, we present a combination of the most precise measurements in each channel to date: M{sub top} = 172.5 {+-} 1.3{sub stat} {+-} 1.9{sub syst} GeV/c{sup 2}.
  • Since the discovery of the top quark in 1995 at the Fermliab Tevatron Collider, top quark properties have been measured with ever higher precision. In this article, recent measurements of the top quark mass and its width using up to 3.6 fb{sup -1} of D0 data are summarized. Different techniques and final states have been examined and no deviations within these measurements have been observed. In addition to the direct measurements, a measurement of the top quark mass from its production cross section and a measurement of the top-antitop quark mass difference are discussed. With a mass of 173.3 {+-}more » 1.1 GeV, the top quark is the heaviest of all known fundamental particles. Due to the high mass, its Yukawa coupling is close to unity suggesting that it may play a special role in electroweak symmetry breaking. Precise measurements of both, the W boson and the top quark mass, constrain the mass of the yet unobserved Higgs boson and allow to restrict certain extensions of the Standard Model. At the Tevatron collider with a center-of-mass energy of 1.96 TeV, 85% of the top quark pairs are produced in quark-antiquark annihilation; 15% originate from gluon fusion. Top quarks are predicted to decay almost exclusively to a W boson and a bottom quark. According to the number of hadronic W decays, top events are classified into all-jets, lepton+jets and dilepton events. The lepton+jets channel is characterized by four jets, one isolated, energetic charged lepton and missing transverse energy. With 30%, the branching fraction of the lepton+jets channel is about seven times larger than the one of the dilepton channel whereas the signal to background ratio is about three times smaller. The main background in this final state comes from W +jets events. Instrumental background arises from events in which a jet is misidentified as an electron and events with heavy hadrons that decay into leptons which pass the isolation requirements. The topology of the dilepton channel is described by two jets, two isolated, energetic charged leptons and significant missing transverse energy from the undetected neutrinos. The main background are Z + jets and diboson events (WW/WZ/ZZ+jets) as well as instrumental background as characterized above. At the D0 experiment, different techniques are used to measure the top quark mass. They are summarized in the following sections together with the first measurement of the top anti-top quark mass difference and the first precise determination of the top quark width.« less
  • Current progress at CDF on the determination of top quark mass in different decay channels is reviewed. Results are based on the final statistics 110 pb{sup -1} of combined run 1a and run 1b.
  • An analysis is presented of 10 W + {ge} 3 jet events, each with evidence for the presence of a b quark, that were recently observed by the CDF collaboration. Seven of these events include a fourth jet and can be explicitly reconstructed as t{bar t} production. The best estimate of the top quark mass is M{sub t} = 174 {+-} 10{sub {minus}12}{sup +13} GeV/c{sup 2}. A study has also been performed to see if the kinematical properties of events with W + {ge} 3 jets gives evidence for top production. An excess of events with large jet energies, comparedmore » to that expected from direct production of W + {ge} 3 jets, is observed. A large fraction of these events also contain a b-quark and a fourth jet.« less