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

TL;DR

This paper investigates analyzing powers in high-energy inclusive pion production using a quark recombination model, highlighting the importance of realistic nucleon spin distributions over SU(6) symmetry assumptions.

Contribution

It introduces a method incorporating realistic nucleon spin distributions to better match experimental data on analyzing powers in pion production.

Findings

Realistic spin distributions improve agreement with experimental analyzing powers.

Predicted asymmetry relation: A_N(K^+) = -A_N(K^0).

Discrepancies with SU(6) symmetry assumptions are addressed.

Abstract

Analyzing powers in inclusive pion production in high energy transversely polarized proton-proton collisions are studied theoretically in the framework of the quark recombination model. Calculations by assuming the SU(6) spin-flavor symmetry for the nucleon structure disagree with the experiments. We solve this difficulty by taking into account the %We overcome this difficulty by taking into account the realistic spin distribution functions of the nucleon, which differs from the SU(6) expectation at large $x$, %but coincides with a perturbative QCD constraint on the ratio of the unpolarized valence distributions, $u/d \to 5$ as $x \to 1$. We also discuss the kaon spin asymmetry and find $A_N(K^+) = -A_N(K^0)$ in the polarized proton-proton collisions at large $x_F$.