  Asymmetries in the quark momentum distributions in the proton reveal
fundamental aspects of strong interaction physics. Differences between u-bar
and d-bar quarks in the proton sea provide insight into the dynamics of the
pion cloud around the nucleon and the nature of chiral symmetry breaking.
Polarized flavor asymmetries allow the effects of pion clouds to be
disentangled from those of antisymmetrization. Asymmetries between s and s-bar
quark distributions in the nucleon are also predicted from the chiral
properties of QCD.
