A new analysis of charge symmetry violation in parton distributions

To date, the strongest indication of charge symmetry violation in parton di stributions 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 precis e tests of charge symmetry with the neutrino data, two conditions must be s atisfied. First, the nuclear shadowing calculations must be made explicitly for neutrinos, not simply taken from muon data on nuclei. Second, the cont ribution of strange and charm quarks should be calculated explicitly using next-to-leading order (NLO) QCD, and the "slow rescaling" charm threshold c orrection should not be applied to the neutrino data. When these criteria a re satisfied, the comparison is consistent with charge symmetry within the experimental errors and the present uncertainty in the strange quark distri bution of the nucleon. (C) 1999 Published by Elsevier Science B.V. All righ ts reserved.