FLAVOR AND CHARGE-SYMMETRY IN THE PARTON DISTRIBUTIONS OF THE NUCLEON

Recent calculations of charge symmetry violation (CSV) in the valence quark distributions of the nucleon have revealed that the dominant sym metry breaking contribution comes from the mass associated with the sp ectator quark system. Assuming that the change in the spectator mass c an be treated perturbatively, we derive a model-independent expression for the shift in the parton distributions of the nucleon. This result is used to derive a relation between the charge- and flavor-asymmetri c contributions to the valence quark distributions in the proton, and to calculate the CSV contribution to the nucleon sea. The CSV contribu tion to the Gottfried sum rule is also estimated, and found to be smal l.