A New Analysis of Charge Symmetry Violation in Parton Distributions

TL;DR

This paper refines tests for charge symmetry violation in parton distributions by emphasizing the need for neutrino-specific nuclear shadowing calculations and explicit strange/charm quark contributions using NLO QCD, leading to results consistent with charge symmetry.

Contribution

It introduces precise conditions for analyzing charge symmetry violation in neutrino data, improving upon previous comparisons with muon data.

Findings

Charge symmetry violation tests depend on neutrino-specific nuclear shadowing.

Explicit NLO QCD calculations of strange and charm quarks are essential.

Results are consistent with charge symmetry within current experimental uncertainties.

Abstract

To date, the strongest indication of charge symmetry violation in parton distributions has been obtained by comparing the $F_2$ structure functions from CCFR neutrino data and NMC muon data. We show that in order to make precise tests of charge symmetry with the neutrino data, two conditions must be satisfied. First, the nuclear shadowing calculations must be made explicitly for neutrinos, not simply taken from muon data on nuclei. Second, the contribution of strange and charm quarks should be calculated explicitly using next-to-leading order [NLO] QCD, and the ``slow rescaling'' charm threshold correction should not be applied to the neutrino data. When these criteria are satisfied, the comparison is consistent with charge symmetry within the experimental errors and the present uncertainty in the strange quark distribution of the nucleon.