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Title: Measurement of the W boson helicity in top quark decays at D0

Abstract

We present a measurement of the fraction f{sub +} of right-handed W bosons produced in top quark decays, based on a candidate sample of tt events in the l+jets and dilepton decay channels corresponding to an integrated luminosity of 370 pb{sup -1} collected by the D0 detector at the Fermilab Tevatron pp Collider at {radical}(s)=1.96 TeV. We reconstruct the decay angle {theta}* for each lepton. By comparing the cos{theta}* distribution from the data with that for the expected background and signal for various values of f{sub +} (where we assume that the fraction of longitudinally-polarized W bosons has the standard model value of 0.70), we find f{sub +}=0.056{+-}0.080(stat){+-}0.057(syst) (f{sub +}<0.23 at 95% C.L.), consistent with the standard model prediction of f{sub +}=3.6x10{sup -4}.

Authors:
; ; ; ; ; ; ;  [1]; ; ; ; ; ; ; ; ;  [2]; ; ;  [3]
  1. Joint Institute for Nuclear Research, Dubna (Russian Federation)
  2. University of Oklahoma, Norman, Oklahoma 73019 (United States)
  3. Michigan State University, East Lansing, Michigan 48824 (United States) (and others)
Publication Date:
OSTI Identifier:
21010959
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevD.75.031102; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA). D0 Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COMPARATIVE EVALUATIONS; DISTRIBUTION; FERMILAB TEVATRON; HELICITY; JET MODEL; LEPTONS; PARTICLE DECAY; STANDARD MODEL; T QUARKS; TEV RANGE; W MINUS BOSONS; W PLUS BOSONS

Citation Formats

Abazov, V. M., Alexeev, G. D., Kalinin, A. M., Kharzheev, Y. M., Malyshev, V. L., Tokmenin, V. V., Vertogradov, L. S., Yatsunenko, Y. A., Abbott, B., Gutierrez, P., Hall, I., Jain, S., Kopal, M., Pompos, A., Severini, H., Skubic, P., Strauss, M., Abolins, M., Benitez, J. A., and Brock, R. Measurement of the W boson helicity in top quark decays at D0. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.031102.
Abazov, V. M., Alexeev, G. D., Kalinin, A. M., Kharzheev, Y. M., Malyshev, V. L., Tokmenin, V. V., Vertogradov, L. S., Yatsunenko, Y. A., Abbott, B., Gutierrez, P., Hall, I., Jain, S., Kopal, M., Pompos, A., Severini, H., Skubic, P., Strauss, M., Abolins, M., Benitez, J. A., & Brock, R. Measurement of the W boson helicity in top quark decays at D0. United States. doi:10.1103/PHYSREVD.75.031102.
Abazov, V. M., Alexeev, G. D., Kalinin, A. M., Kharzheev, Y. M., Malyshev, V. L., Tokmenin, V. V., Vertogradov, L. S., Yatsunenko, Y. A., Abbott, B., Gutierrez, P., Hall, I., Jain, S., Kopal, M., Pompos, A., Severini, H., Skubic, P., Strauss, M., Abolins, M., Benitez, J. A., and Brock, R. Thu . "Measurement of the W boson helicity in top quark decays at D0". United States. doi:10.1103/PHYSREVD.75.031102.
@article{osti_21010959,
title = {Measurement of the W boson helicity in top quark decays at D0},
author = {Abazov, V. M. and Alexeev, G. D. and Kalinin, A. M. and Kharzheev, Y. M. and Malyshev, V. L. and Tokmenin, V. V. and Vertogradov, L. S. and Yatsunenko, Y. A. and Abbott, B. and Gutierrez, P. and Hall, I. and Jain, S. and Kopal, M. and Pompos, A. and Severini, H. and Skubic, P. and Strauss, M. and Abolins, M. and Benitez, J. A. and Brock, R.},
abstractNote = {We present a measurement of the fraction f{sub +} of right-handed W bosons produced in top quark decays, based on a candidate sample of tt events in the l+jets and dilepton decay channels corresponding to an integrated luminosity of 370 pb{sup -1} collected by the D0 detector at the Fermilab Tevatron pp Collider at {radical}(s)=1.96 TeV. We reconstruct the decay angle {theta}* for each lepton. By comparing the cos{theta}* distribution from the data with that for the expected background and signal for various values of f{sub +} (where we assume that the fraction of longitudinally-polarized W bosons has the standard model value of 0.70), we find f{sub +}=0.056{+-}0.080(stat){+-}0.057(syst) (f{sub +}<0.23 at 95% C.L.), consistent with the standard model prediction of f{sub +}=3.6x10{sup -4}.},
doi = {10.1103/PHYSREVD.75.031102},
journal = {Physical Review. D, Particles Fields},
number = 3,
volume = 75,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb{sup -1} sample of candidate t{bar t} events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider. We reconstruct the angle {theta}* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos {theta}* distribution finds that the fraction of longitudinal W bosons f{sub 0} = 0.390 {+-} 0.177 (stat.) {+-}more » 0.104 (syst.) and the fraction of right-handed W bosons f{sub +} = 0.171 {+-} 0.102 (stat.) {+-} 0.058 (syst.), which is consistent at the 27% C.L. with the standard model.« less
  • We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb{sup -1} sample of candidate tt events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron pp Collider. We reconstruct the angle {theta}* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos{theta}* distribution finds that the fraction of longitudinal W bosons f{sub 0}=0.425{+-}0.166(stat){+-}0.102(syst) and the fraction of right-handed W bosons f{sub +}=0.119{+-}0.090(stat){+-}0.053(syst),more » which is consistent at the 30% C.L. with the standard model.« less
  • 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 ofmore » 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.« less
  • Cited by 27