Anomalous Quark Chromomagnetic Moment and Single-Spin Asymmetries

We discuss a nonperturbative mechanism for the single-spin asymmetries (SSA) in the strong interaction. This mechanism is based on the existence of a large anomalous quark chromomagnetic moment (AQCM) induced by the nontrivial topological structure of QCD vacuum. Our estimations within the instanton liquid model for QCD vacuum show that AQCM generates very large SSA on the quark level. Therefore, this mechanism can be responsible for the anomalously large SSA observed in different high energy reactions with hadrons.