Semi Inclusive Deep Inelastic Scattering: nonperturbative and perturbative regimes

Abstract

We consider the azimuthal and P T dependence of hadrons produced in unpolarized Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes, within the factorized QCD parton model. It is shown that at small P T values, P T ∼ < 1 GeV/c, lowest order contributions, coupled to unintegrated (Transverse Momentum Dependent) quark distribution and fragmentation functions, describe all data. At larger P T values, P T ∼ > 1 GeV/c, the usual pQCD higher order collinear contributions dominate.Having explained the full P T range of available data, we give new detailed predictions concerning the azimuthal and P T dependence of hadrons which could be measured in ongoing or planned experiments by HERMES, COMPASS and JLab collaborations.