Phenomenological analysis of azimuthal asymmetries in unpolarized semi-inclusive deep inelastic scattering

Abstract

We present a phenomenological analysis of the cosφ and cos2φ asymmetries in unpolarized semi-inclusive deep inelastic scattering, based on the recent multidimensional data released by the COMPASS and HERMES collaborations. In the transverse-momentum-dependent framework, valid at relatively low transverse momenta, these asymmetries arise from intrinsic transverse momentum and transverse spin effects, and from their correlations. The role of the Cahn and Boer-Mulders effects in both azimuthal moments is explored up to order 1/Q. As the kinematics of the present experiments is dominated by the low-Q2 region, higher-twist contributions turn out to be important, affecting the results of our fits.