Evidence for charge symmetry violation in parton distributions

Abstract

A comparison of the structure functions measured in neutrino and charged lepton deep inelastic scattering can be used to test basic properties of parton distribution functions such as charge symmetry. Recent data from the CCFR and NMC groups indicate a substantial discrepancy between Fν2 and Fμ2 in the small-x region. We show that neither nuclear corrections nor strange quark effects can account for the observed discrepancy. These results suggest that the nucleon sea exhibits surprisingly large charge symmetry violation.