Single spin asymmetries in ℓp↑→hX processes and transverse momentum dependent factorization

Abstract

Some estimates for the transverse single spin asymmetry, ${A}_{N}$, in the inclusive processes $\ensuremath{\ell}{p}^{\ensuremath{\uparrow}}\ensuremath{\rightarrow}hX$, given in a previous paper, are expanded and compared with new experimental data. The predictions are based on the Sivers distributions and the Collins fragmentation functions which fit the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) processes ($\ensuremath{\ell}{p}^{\ensuremath{\uparrow}}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{\ensuremath{'}}hX$). The factorization in terms of transverse momentum dependent distribution and fragmentation functions (TMD factorization)---i.e. the theoretical framework in which SIDIS azimuthal asymmetries are analyzed---is assumed to hold also for the inclusive process $\ensuremath{\ell}p\ensuremath{\rightarrow}hX$ at large ${P}_{T}$. The values of ${A}_{N}$ thus obtained agree in sign and shape with the data. Some predictions are given for future experiments.