VALIDITY OF FLAVOR SYMMETRY AND CHARGE-SYMMETRY FOR PARTON DISTRIBUTIONS

Measurements of the Gottfried Sum Rule suggest significant violation o f flavor symmetry in the proton sea. This has recently been confirmed in measurements of pp and pD Drell-Yan processes by the E866 experimen t. We review the question of flavor symmetry violation, and possible t heoretical explanations of this effect. The interpretation of large fl avor symmetry violation rests on the assumption of parton charge symme try. Our model calculations suggest charge symmetry violation [CSV] fo r parton valence distributions of a few percent. We review present exp erimental limits on CSV, and we suggest new experiments which might de tect parton CSV.