Flavor symmetry breaking in the $\Delta$ sea

Abstract

The discovery of a sizeable asymmetry in the $\bar u$ and $\bar d$ distributions in the proton was one of the more consequential experimental findings in hadron physics last century. Although widely believed to be related to the fundamental role of chiral symmetry in QCD, a definitive verification of this hypothesis has remained elusive. We propose a novel test of the role of chiral symmetry in generating the sea flavor asymmetry by comparing the $\bar d-\bar u$ content in the proton with that in the $\Delta^+$ baryon, where a significant enhancement is expected around the opening of the $N \pi$ decay channel. Recent developments in lattice QCD suggest a promising way to test this prediction in the near future.