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Title: Parton charge symmetry violation: Electromagnetic effects and W production asymmetries

Abstract

Recent phenomenological work has examined two different ways of including charge symmetry violation in parton distribution functions. First, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the magnitude of parton charge symmetry breaking. In a second approach, two groups have included the coupling of partons to photons in the QCD evolution equations. One possible experiment that could search for isospin violation in parton distributions is a measurement of the asymmetry in W production at a collider. In this work we include both of the postulated sources of parton charge symmetry violation. We show that, given charge symmetry violation of a magnitude consistent with existing high energy data, the expected W production asymmetries would be quite small, generally less than 1%.

Authors:
; ;  [1];  [2];  [2]
  1. Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana 47405 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20782850
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 7; Other Information: DOI: 10.1103/PhysRevD.73.076004; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; C INVARIANCE; COUPLING; DISTRIBUTION; DISTRIBUTION FUNCTIONS; GLUONS; ISOSPIN; PHOTONS; QUANTUM CHROMODYNAMICS; QUARKS; SYMMETRY BREAKING

Citation Formats

Londergan, J.T., Murdock, D.P., Thomas, A.W., Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505, and Jefferson Lab, 12000 Jefferson Ave., Newport News, Virginia 23606. Parton charge symmetry violation: Electromagnetic effects and W production asymmetries. United States: N. p., 2006. Web. doi:10.1103/PHYSREVD.73.076004.
Londergan, J.T., Murdock, D.P., Thomas, A.W., Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505, & Jefferson Lab, 12000 Jefferson Ave., Newport News, Virginia 23606. Parton charge symmetry violation: Electromagnetic effects and W production asymmetries. United States. doi:10.1103/PHYSREVD.73.076004.
Londergan, J.T., Murdock, D.P., Thomas, A.W., Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505, and Jefferson Lab, 12000 Jefferson Ave., Newport News, Virginia 23606. Sat . "Parton charge symmetry violation: Electromagnetic effects and W production asymmetries". United States. doi:10.1103/PHYSREVD.73.076004.
@article{osti_20782850,
title = {Parton charge symmetry violation: Electromagnetic effects and W production asymmetries},
author = {Londergan, J.T. and Murdock, D.P. and Thomas, A.W. and Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505 and Jefferson Lab, 12000 Jefferson Ave., Newport News, Virginia 23606},
abstractNote = {Recent phenomenological work has examined two different ways of including charge symmetry violation in parton distribution functions. First, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the magnitude of parton charge symmetry breaking. In a second approach, two groups have included the coupling of partons to photons in the QCD evolution equations. One possible experiment that could search for isospin violation in parton distributions is a measurement of the asymmetry in W production at a collider. In this work we include both of the postulated sources of parton charge symmetry violation. We show that, given charge symmetry violation of a magnitude consistent with existing high energy data, the expected W production asymmetries would be quite small, generally less than 1%.},
doi = {10.1103/PHYSREVD.73.076004},
journal = {Physical Review. D, Particles Fields},
number = 7,
volume = 73,
place = {United States},
year = {Sat Apr 01 00:00:00 EST 2006},
month = {Sat Apr 01 00:00:00 EST 2006}
}
  • Recent phenomenological work has examined two different ways of including charge symmetry violation in parton distribution functions. First, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the magnitude of parton charge symmetry breaking. In a second approach, two groups have included the coupling of partons to photons in the QCD evolution equations. One possible experiment that could search for isospin violation in parton distributions is a measurement of the asymmetry in W production at a collider. In this work we include both of the postulated sources of parton charge symmetrymore » violation. We show that, given charge symmetry violation of a magnitude consistent with existing high energy data, the expected W production asymmetries would be quite small, generally less than one percent.« less
  • We present a next-to-leading-order QCD calculation of the cross section and longitudinal spin asymmetry in single-inclusive charged-lepton production, pp{yields}l{sup {+-}X}, at the Relativistic Heavy Ion Collider, where the lepton is produced in the decay of an electroweak gauge boson. Our calculation is presented in terms of a multipurpose Monte Carlo integration program that may be readily used to include experimental spin-asymmetry data in a global analysis of helicity parton densities. We perform a toy global analysis, studying the impact of anticipated Relativistic Heavy Ion Collider data on our knowledge about the polarized antiquark distributions.
  • Recently, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the allowed magnitude of such effects. We discuss two possible experiments that could search for isospin violation in valence parton distributions. We show that, given the magnitude of charge symmetry violation consistent with existing global data, such experiments might expect to see effects at a level of several percent. Alternatively, such experiments could significantly decrease the upper limits on isospin violation in parton distributions.
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