Hadronization in semi-inclusive deep-inelastic scattering on nuclei

Abstract: A series of semi-inclusive deep-inelastic scattering measurements on deuterium, helium, neon, krypton, and xenon targets has been performed in order to study hadronization. The data were collected with the HERMES detector at the DESY laboratory using a 27.6 GeV positron or electron beam. Hadron multiplicities on nucleus A relative to those on the deuteron, , are presented for various hadrons (, , , , , p, and ) as a function of the virtual-photon energy ν, the fraction z of this energy transferred to the hadron, the photon virtuality , and the hadron transverse momentum squared . The data reveal a systematic decrease of with the mass number A for each hadron type h. Furthermore, increases (decreases) with increasing values of ν (z), increases slightly with increasing , and is almost independent of , except at large values of . For pions two-dimensional distributions also are presented. These indicate that the dependences of on ν and z can largely be described as a dependence on a single variable , which is a combination of ν and z. The dependence on suggests in which kinematic conditions partonic and hadronic mechanisms may be dominant. The behaviour of at large constitutes tentative evidence for a partonic energy-loss mechanism. The A-dependence of is investigated as a function of ν, z, and of . It approximately follows an form with . [Copyright &y& Elsevier]