A phenomenological study of single transverse-spin asymmetry for   inclusive light-hadron productions at RHIC
  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 $\pi^0$. 
Koichi Kanazawa and Yuji Koike
hep-ph