Strategy towards the extraction of the Sivers function with transverse momentum dependent evolution

Abstract

The QCD evolution of the unpolarized transverse momentum dependent (TMD) distribution functions and of the Sivers functions have been discussed in recent papers. Following such results we reconsider previous extractions of the Sivers functions from semi-inclusive deep inelastic scattering data and propose a simple strategy which allows to take into account the ${Q}^{2}$ dependence of the TMDs in comparison with experimental findings. A clear evidence of the phenomenological success of the TMD-evolution equations is given, mostly, by the newest COMPASS data off a transversely polarized proton target.