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.