Single Spin Effects in Collisions of Hadrons and Heavy Ions at High Energy

Abstract

Experimental data on transverse single-spin asymmetry, hyperon polarization and vector meson alignment in h+h, h+A and A+A-collisions have been analyzed. A new mechanism for the origin of single spin effects is proposed, which takes into account the interaction of massive constituent quarks via their chromomagnetic moment with an effective inhomogeneous chromomagnetic field of strings, produced after the initial color exchange. Quark spin precession in the color field is taken into account, which can be the reason for an oscillation of the single spin observables as a function of Feynman $x_{F}$ and its energy dependence. The model predictions are compared with the experimental data, in particular with the heavy ion collision data. The data are consistent with a large negative anomalous chromomagnetic moment of the constituent quarks which is predicted in the instanton model.