Azimuthal single- and double-spin asymmetries in semi-inclusive deep-inelastic lepton scattering by transversely polarized protons

A comprehensive set of azimuthal single-spin and double-spin asymmetriesin semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons fromtransversely polarized protons is presented. These asymmetries include the previouslypublishedHERMESresults on Collins and Sivers asymmetries, the analysis of which hasbeen extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented bycorresponding results for the remaining four single-spin and four double-spin asymme-tries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelasticscattering process for target-polarization orientation perpendicular to the direction of theincoming lepton beam. Among those results, significant non-vanishingcos (φ−φS)modu-lations provide evidence for a sizable worm-gear (II) distribution,gq1T(x,p2T). Most of theother modulations are found to be consistent with zero with the notable exception of largesin (φS)modulations for charged pions andK+.