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

Abstract

A measurement of the fraction, f +, 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 -1, collected by the D0 detector at the Fermilab Tevatron p$$\bar{p}$$ Collider at √s = 1.96 TeV. The helicity angle, θ*, is reconstructed for each lepton. f + is determined by comparing the cos θ* distribution from the data with that for the expected background and signal for various values of f +. The fraction of longitudinal W bosons, f 0, is assumed to be 0.7 as predicted by the standard model. This yields f + = 0.109 ± 0.094 (stat) ± 0.063 (syst), consistent with the standard model prediction of f + = 3.6x 10 -4. The possibility that both f + and f 0 stray from standard model values is also investigated. In this case cos θ* distributions for each possible W helicity state, along with the backgrounds, are fit to the cos θ* distribution for the data. The best fit values are f + = 0.82 ± 0.30(stat) and f 0 = -0.58 ± 0.50(stat).

Authors:
 [1]
  1. Univ. of Arizona, Tucson, AZ (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
919582
Report Number(s):
FERMILAB-THESIS-2007-32
TRN: US0806446
DOE Contract Number:
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DISTRIBUTION; FERMILAB TEVATRON; HELICITY; INTERMEDIATE BOSONS; LUMINOSITY; STANDARD MODEL; T QUARKS; Experiment-HEP

Citation Formats

Gmyrek, Bryan David. Measurement of the W boson helicity in top quark decays. United States: N. p., 2007. Web. doi:10.2172/919582.
Gmyrek, Bryan David. Measurement of the W boson helicity in top quark decays. United States. doi:10.2172/919582.
Gmyrek, Bryan David. Mon . "Measurement of the W boson helicity in top quark decays". United States. doi:10.2172/919582. https://www.osti.gov/servlets/purl/919582.
@article{osti_919582,
title = {Measurement of the W boson helicity in top quark decays},
author = {Gmyrek, Bryan David},
abstractNote = {A measurement of the fraction, f+, 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-1, collected by the D0 detector at the Fermilab Tevatron p$\bar{p}$ Collider at √s = 1.96 TeV. The helicity angle, θ*, is reconstructed for each lepton. f+ is determined by comparing the cos θ* distribution from the data with that for the expected background and signal for various values of f+. The fraction of longitudinal W bosons, f0, is assumed to be 0.7 as predicted by the standard model. This yields f+ = 0.109 ± 0.094 (stat) ± 0.063 (syst), consistent with the standard model prediction of f+ = 3.6x 10-4. The possibility that both f+ and f0 stray from standard model values is also investigated. In this case cos θ* distributions for each possible W helicity state, along with the backgrounds, are fit to the cos θ* distribution for the data. The best fit values are f+ = 0.82 ± 0.30(stat) and f0 = -0.58 ± 0.50(stat).},
doi = {10.2172/919582},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Thesis/Dissertation:
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