Transverse single-spin asymmetries in lp↑ → hX within a TMD approach: Role of quasireal photon exchange

We present an updated study of transverse single-spin asymmetries for the inclusive large-PT processes p↑→hX and p↑→jetX, within a transverse momentum-dependent approach, including the contribution of quasireal (Weizsäcker-Williams) photons. In the spirit of a unified transverse momentum-dependent scheme, predictions are obtained adopting the Sivers and transversity distributions and the Collins fragmentation functions as extracted from fits to the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering and e+e- annihilation processes. The description of the available data is extremely good, showing a clear general improvement with respect to the previous leading-order analysis. Predictions for unpolarized cross sections and single-spin asymmetries for ongoing and future experiments are also given.