Nuclear medium effects on hadronization measured by the Hermes collaboration

The effects of the cold nuclear medium on hadron multiplicities in semi-inclusive deep inelastic scattering was studied extensively and is presented together with the first direct measurement of pt-broadening in cold nuclear matter. The data have been accumulated by the Hermes experiment at Desy, in which the Hera 27.6 GeV lepton beam scattered off several nuclear gas targets. These analysis provide precious information concerning the space-time evolution of hadronization.