Implication of W-boson Charge Asymmetry Measurements in p-pbar Collisions for Models of Charge Symmetry Violations in Parton Distributions

TL;DR

This paper uses W-boson charge asymmetry data from proton-antiproton collisions to test models of charge symmetry violation in nucleon parton distributions, ruling out some proposed large violations.

Contribution

It demonstrates that recent experimental W asymmetry measurements constrain and disprove certain models of charge symmetry violation in nucleon sea quarks.

Findings

CDF W charge asymmetry measurements strongly constrain d/u quark ratios.

Models proposing large charge symmetry violations are inconsistent with data.

Constraints reduce systematic errors in sin^2(theta) measurements from neutrino scattering.

Abstract

A surprisingly large charge symmetry violation of the sea quarks in the nucleon has been proposed in a recent article by Boros et al. as an explanation of the discrepancy between neutrino (CCFR) and muon (NMC) nucleon structure function data at low x. We show that these models are ruled out by the published CDF W charge asymmetry measurements, which strongly constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34. This constraint also limits the systematic error from possible charge symmetry violation in the determination of sin^2(theta) from nu-N scattering experiments.