Flavor asymmetry of the polarized sea-quark distributions in the proton

Abstract

The recent global analysis of helicity parton distributions, which takes into account available data from inclusive and semi-inclusive polarized deep inelastic scattering, as well as from polarized proton-proton scattering at RHIC, appears to offer the first strong evidence that polarized sea-quark distributions are flavor asymmetric, i.e. $\Delta \bar{u}(x) \ne \Delta \bar{d}(x)$. We point out that the flavor symmetry breaking pattern indicated by their analysis, i.e. $\Delta \bar{u}(x) > 0$ and $\Delta \bar{d}(x) < 0$ with the magnitude correlation $|\Delta \bar{u}(x)| < |\Delta \bar{d}(x)|$, is just consistent with our theoretical predictions given several years ago on the basis of the chiral quark soliton model. We also address ourselves to understanding the physics behind this observation.