Intrinsic transverse parton momenta in deeply inelastic reactions

It is shown that intrinsic transverse parton momenta p T in semi-inclusive deep-inelastic scattering (SIDIS) and the Drell-Yan process (DY) are very well and consistently described in the Gauss model with energy-dependent Gaussian widths. Our work solidifies the basis for future studies of p T -effects. We also discuss the Cahn and Boer-Mulders effect in SIDIS and DY.