Microscopic Stern-Gerlach Effect and Thomas Spin Precession as an Origin of the SSA

Abstract

The single-spin asymmetry and hadron polarization data are analyzed in the framework of a phenomenological effective-color-field model. Global analysis of the single-spin effects in hadron production is performed for h+h, h+A, A+A and lepton+N interactions. The model explains the dependence of the data on $x_F$, $p_T$, collision energy $\sqrt{s}$ and atomic weights $A_1$ and $A_2$ of colliding nuclei. The predictions are given for not yet explored kinematical regions.

Comments: 4 pages, LaTeX, 4 figures, Presented at the XIII Advanced Research Workshop on High Energy Spin Physics (DUBNA-SPIN-09), Dubna, Russia, September 1-5, 2009