A phenomenological study of single transverse-spin asymmetry for inclusive light-hadron productions at RHIC

TL;DR

This study investigates the single transverse-spin asymmetry in inclusive light-hadron production at RHIC energies using the twist-3 collinear factorization approach, providing predictions for higher energy collisions and different mesons.

Contribution

It offers a comprehensive twist-3 analysis including all relevant pole contributions and predicts asymmetries at 500 GeV for various light mesons, extending previous lower-energy studies.

Findings

Asymmetry slightly decreases at 500 GeV compared to lower energies.

The eta meson shows a significantly larger asymmetry than pi0.

Predictions for asymmetries at RHIC energies for different mesons.

Abstract

We study the single transverse-spin asymmetry for inclusive light-hadron productions in the proton-proton collision, $\pphx$ ($h=\pi,K,\eta$), for the RHIC kinematics based on the twist-3 mechanism in the collinear factorization. The analysis includes all the contributions from the soft-gluon pole and the soft-fermion pole for the twist-3 quark-gluon correlation functions in the transversely polarized proton. After discussing the flavor decomposition and the $P_T$-dependence of the asymmetry obtained in the previous analysis at the center-of-mass energy $\sqrt{S}=62.4$ and 200 GeV, we will give a prediction for the asymmetry at $\sqrt{S}=500$ GeV and also for the $\eta$-meson production. We found slightly smaller asymmetry at $\sqrt{S}=500$ GeV for $\pi^{\pm,0}$ and $K^+$ compared with those at the lower energies. The asymmetry for the $\eta$-meson turned out to be significantly larger than that for $\pi^0$.