Distortions in the negative energy Dirac sea : violation of the Gottfried sum rule and ∆ ū in proton

Distortions in the negative energy Dirac sea: violation of the Gottfried sum rule and ∆¯ u in proton We report on recent work concerning the effect which the change in vacuum structure (negative energy Dirac sea), in the presence of a confining scalar field, has on the nucleon structure functions and parton distributions. Using the Dirac equation in 1+1 dimensions, we show that distortions in the Dirac sea are responsible for part of the violation of the Gottfried sum rule – i.e., part of the flavor asymmetry in the proton sea. Our basic argument is that, even if isospin is an exact symmetry, the presence of a confining potential changes the vacuum structure, and inevitably leads to a violation of SU(2) flavour symmetry in a hadron with a different number of valence u and d quarks. The same mechanism also leads to a prediction for ∆¯ u and ∆ ¯ d.