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Title: Measurement of the strange quark distribution function in W + charm quark events

Abstract

We investigate the prospects of measuring the strange quark distribution function at the Tevatron, using W plus charm quark events. The W plus charm quark events. The W plus charm quark signal produced by strange quark - gluon fusion, sg {yields} W {sup {minus}}c and {bar s}g {yields} W {sup +} W+ charm quark cross section to the parametrization of the strange quark distribution function, and evaluate the various background processes. The different prospects of tagging the charm quark with the CDF and D{theta} detectors are briefly discussed.

Authors:
;  [1]; ;  [2];  [3]
  1. Florida State Univ., Tallahassee, FL (United States). Dept. of Physics
  2. Wisconsin Univ., Madison, WI (United States). Dept. of Physics
  3. Scuola Normale Superiore, Pisa (Italy)|[Istituto Nazionale di Fisica Nucleare, Pisa (Italy). Dipt. di Fisica
Publication Date:
Research Org.:
Florida State Univ., Tallahassee, FL (United States). Dept. of Physics; Wisconsin Univ., Madison, WI (United States). Dept. of Physics
Sponsoring Org.:
USDOE, Washington, DC (United States); Texas National Research Lab. Commission, De Soto, TX (United States)
OSTI Identifier:
10179676
Report Number(s):
FSU-HEP-930608
ON: DE93018267; CNN: Grant RGFY9273; TRN: 93:019908
DOE Contract Number:
FG05-87ER40319; AC02-76ER00881
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 24 Jun 1993
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; QUARKS; DISTRIBUTION FUNCTIONS; STRANGENESS; QUARK-GLUON INTERACTIONS; TRANSVERSE MOMENTUM; W PLUS BOSONS; INELASTIC SCATTERING; FERMILAB COLLIDER DETECTOR; CROSS SECTIONS; CHARM PARTICLES; 662440; PROPERTIES OF OTHER PARTICLES INCLUDING HYPOTHETICAL PARTICLES

Citation Formats

Baur, U., Keller, S., Halzen, F., Riesselmann, K., and Mangano, M.L. Measurement of the strange quark distribution function in W + charm quark events. United States: N. p., 1993. Web. doi:10.2172/10179676.
Baur, U., Keller, S., Halzen, F., Riesselmann, K., & Mangano, M.L. Measurement of the strange quark distribution function in W + charm quark events. United States. doi:10.2172/10179676.
Baur, U., Keller, S., Halzen, F., Riesselmann, K., and Mangano, M.L. Thu . "Measurement of the strange quark distribution function in W + charm quark events". United States. doi:10.2172/10179676. https://www.osti.gov/servlets/purl/10179676.
@article{osti_10179676,
title = {Measurement of the strange quark distribution function in W + charm quark events},
author = {Baur, U. and Keller, S. and Halzen, F. and Riesselmann, K. and Mangano, M.L.},
abstractNote = {We investigate the prospects of measuring the strange quark distribution function at the Tevatron, using W plus charm quark events. The W plus charm quark events. The W plus charm quark signal produced by strange quark - gluon fusion, sg {yields} W {sup {minus}}c and {bar s}g {yields} W {sup +} W+ charm quark cross section to the parametrization of the strange quark distribution function, and evaluate the various background processes. The different prospects of tagging the charm quark with the CDF and D{theta} detectors are briefly discussed.},
doi = {10.2172/10179676},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jun 24 00:00:00 EDT 1993},
month = {Thu Jun 24 00:00:00 EDT 1993}
}

Technical Report:

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  • In 1995 the top quark was discovered at the Tevatron proton-antiproton collider at Fermilab by the CDF and D0 collaborations [1, 2]. It is the most massive known elementary particle and its mass is currently measured with a precision of about 1.3% [3, 4]. However, the measurements of several other top quark properties are still statistically limited, so the question remains whether the Standard Model of elementary particle physics successfully predicts these properties. This thesis addresses one interesting aspect of top quark decay, the helicity of the produced W boson. Until the start of the Large Hadron Collider (LHC) atmore » CERN, the Tevatron with a center-of-mass energy of {radical}s = 1.96 TeV is the only collider, where top quarks can be produced. In the Standard Model the top quark decays predominantly into a W boson and a b quark, with a branching ratio close to 100%. The V-A structure of the weak interaction of the Standard Model predicts that the W{sup +} bosons from the top quark decay t {yields} W{sup +}b are dominantly either longitudinally polarized or left handed, while right handed W bosons are heavily suppressed and even forbidden in the limit of a massless b quark. Under the assumption of a massless b quark, for a top quark mass of 173 GeV/c{sup 2} the Standard Model predicts the fraction F0 of longitudinally polarized W bosons to be 0.7 and 0.3 for the fraction F{_} of left handed W bosons, while the fraction F{sub +} of right handed W bosons is predicted to be zero. Since next-to-leading order corrections change these fractions only slightly, a significant deviation from the predicted value for F{sub 0} or a nonzero value for F{sub +} could indicate new physics. Left-right symmetric models [5], for example, lead to a significant right handed fraction of W bosons in top decays. Such a right handed component (V+A coupling) would lead to a smaller left handed fraction, while F{sub 0} would remain unchanged. Since the decay rate to longitudinal W bosons depends on the Yukawa coupling of the top quarks, the measurement of F{sub 0} is sensitive to the mechanism of electroweak symmetry breaking. Alternative models can lead to an altered F{sub 0} fraction. In this analysis the W helicity fractions are measured in a selected sample rich in t{bar B} events where one lepton, at least four jets, and missing transverse energy are required. All kinematic quantities describing the t{bar t} decay are determined. As a sensitive observable, we use the cosine of the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W boson momentum in the top quark rest frame. The data used in this analysis were taken with the Collider Detector at Fermilab (CDF II) in the years 2002-2006 and correspond to an integrated luminosity of about 955 pb{sup -1}. Previous CDF measurements of the W boson helicity fractions in top quark decays used either the square of the invariant mass of the charged lepton and the b quark jet, M{sub {ell}b}{sup 2}, or the lepton p{sub T} distribution as a discriminant. The D0 collaboration used a matrix-element method to extract a value of F{sub 0}; in a second analysis the reconstructed distribution of cos {theta}* was utilized to measure F{sub +}. CDF gives the latest value of F{sub 0} = 0.74{sub -0.34}{sup +0.22}, while D measured F{sub 0} = 0.56 {+-} 0.31. The CDF collaboration also gives the current upper limit of F{sub +} < 0.09.« less
  • The goal of this work is to study the behavior of the angular distribution of the electron from the decay of the W boson in a specific rest frame of the W, the Collins-Soper frame. More specifically, the parameter {alpha}{sub 2} from the expression d{sigma}/d(P{sub T}{sup W}){sup 2} d cos {theta}* = k(1 + {alpha}{sub 2} cos {theta}* + {alpha}{sup 2}(cos {theta}*){sup 2}), corresponding to the distribution of cos {theta}* in the Collins-Soper frame, was measured. The experimental value of {alpha}P{sub 2} was compared with the predictions made by E. Mirkes [11] who included the radiative QCD perturbations in themore » weak-interaction B{sub boson} {r_arrow} lepton + lepton. This experimental value was extracted for the first time using knowledge about how the radiative QCD perturbations will modify the predictions given by the Electro-Weak process only.« less
  • The BABAR experiment at SLAC provides an opportunity for measurement of CP violation in B decays. A measurement of time-dependent CP violating asymmetries using exclusive B meson decays where the b quark decays to c{bar c}d (including B{sup 0} {yields} D*{sup +}D*{sup -} and B{sup 0} {yields} D*{sup {+-}}D{sup {-+}} decays) is presented here. This is the first measurement of CP violation in a mode sensitive to the Unitarity Triangle parameter sin2{beta} outside of decays containing charmonium. It provides a comparison to measurements of sin2{beta} using b {yields} c{bar c}s, and permits an observation into potential new physics sources ofmore » CP violation, such as supersymmetry, via differences between these measurements and those of B{sup 0} {yields} J/{psi} K{sub S}{sup 0} as statistics of reconstructed neutral B decays to D{sup (*)+} D{sup (*)-} increase. The measured value of the time-dependent CP violating asymmetries are: S = 0.38 {+-} 0.88(stat) {+-} 0.12(syst) and C = -0.30 {+-} 0.50(stat) {+-} 0.13(syst) for B{sup 0} {yields} D*{sup -} D{sup +}; S = -0.43 {+-} 1.41(stat) {+-} 0.23(syst) and C = 0.53 {+-} 0.74(stat) {+-} 0.15(syst) for B{sup 0} {yields} D*{sup +} D{sup -}; and S = -0.05 {+-} 0.45(stat) {+-} 0.05(syst) and C = 0.12 {+-} 0.30(stat) {+-} 0.05(syst) for B{sup 0} {yields} D*{sup -} D{sup +}; where S corresponds to CP violation in the interference of mixing and decay and C corresponds to CP violation in decay.« less
  • We have analyzed experimental data on (i)e/sup +/e/sup -/ annihilation to hadrons, (ii) leptoproduction, (iii) hadron-hadron interactions, and (iv) heavy particle decays to determine SU(3) symmetry violation, i.e., the suppression factor (lambda) for strange quark-antiquark pairs relative to u anti u and d anti d pairs in the hadronic vacuum. Inclusive particle ratios, i.e., K/..pi.. ratios at large x and ratios between the inclusive production rates of relevant resonances, yield similar values for lambda, the weighted mean being < lambda > = 0.29 +- 0.02. No significant energy dependence of lambda is observed. We also find that the average netmore » electric charge measurements for lepton produced quark jets are consistent with the above value of lambda.« less