Sivers effect and the single spin asymmetry AN in p(up arrow) p --> h X processes

The single spin asymmetry AN, for large PT single inclusive particle production in pp collisions, is considered within a generalized parton model and a transverse momentum dependent factorization scheme. The focus is on the Sivers effect and the study of its potential contribution to AN, based on a careful analysis of the Sivers functions extracted from azimuthal asymmetries in semi-inclusive deep inelastic scattering processes. It is found that such Sivers functions could explain most features of the AN data, including some recent STAR results which show the persistence of a nonzero AN up to surprisingly large PT values.