Double spin azimuthal asymmetries A_{LT} and A_{LL} in semi-inclusive DIS

Abstract

Within the LO QCD parton model of SIDIS with unintegrated quark distribution and fragmentation functions we study the transverse momentum and azimuthal dependencies of the double spin asymmetries $A_{LT}$ and $A_{LL}$. For later we include ${\cal O}(k_{\perp}/Q)$ kinematic corrections, which induce an azimuthal modulation of the asymmetry, analogous to the Cahn effect in unpolarized SIDIS. We show that a study of these asymmetries allows to extract the transverse momentum dependence of the unintegrated helicity distribution function $g_{1L}^q(x,k_\perp)$ and $g_{1T}^q(x,k_\perp)$. This report is based on research published in [1] and [2], where predictions are given for ongoing COMPASS, HERMES and JLab experiments.