Analyzing powers in inclusive pion production at high energy and the nucleon spin structure

Analyzing powers in inclusive pion production in high energy transversely p olarized proton-proton collisions are studied theoretically in the framewor k of the quark recombination model. Calculations by assuming the SU(6) spin -flavor symmetry for the nucleon structure disagree with the experiments. W e solve this difficulty by taking into account the realistic spin distribut ion functions of the nucleon, which differs from the SU(6) expectation at l arge x, with a perturbative QCD constraint on the ratio of the unpolarized valence distributions, u/d --> 5 as x --> 1. We also discuss the kaon spin asymmetry and find A(N)(K+) = - A(N)(K-O) in the polarized proton-proton co llisions at large x(F).