We present a detailed theoretical investigation of hadron attenuation in deep inelastic scattering (DIS) off complex nuclei in the kinematic regime of the HERMES experiment. The analysis is carried out in the framework of a probabilistic coupled-channel transport model based on the Boltzmann-Uehling-Uhlenbeck (BUU) equation, which allows for a treatment of the final-state interactions (FSI) beyond simple absorption mechanisms. Furthermore, our event-by-event simulations account for the kinematic cuts of the experiments as well as the geometrical acceptance of the detectors. We calculate the multiplicity ratios of charged hadrons for various nuclear targets relative to deuterium as a function of the photon energy nu, the hadron energy fraction z_h=E_h/nu and the transverse momentum p_T. We also confront our model results on double-hadron attenuation with recent experimental data. Separately, we compare the attenuation of identified hadrons (pi^\pm, \pi^0, K^\pm, p and pbar) on Ne and Kr targets with the data from the HERMES Collaboration and make predictions for a Xe target. At the end we turn towards hadron attenuation on Cu nuclei at EMC energies. Our studies demonstrate that (pre-)hadronic final-state interactions play a dominant role in the kinematic regime of the HERMES experiment while our present approach overestimates the attenuation at EMC energies.Comment: 61 pages, 19 figures, version accepted for publication in Phys. Rev.

We investigate inclusive ω photoproduction off complex nuclei, concentrating on the feasibility to examine a possible in-medium change of the ω meson properties by observing the π 0 γ invariant mass spectrum. The simulations are performed by means of a BUU transport model including a full coupled-channel treatment of the final state interactions. In-medium changes of the ω spectral density are found to yield a moderate modification of the observables as compared to the situation in free space. Also the effects of a momentum dependence of the strong ω potential are discussed.

No abstract

We examine the space-time evolution of (pre-)hadron production within the Lund string fragmentation model. The complete four-dimensional information of the string breaking vertices and the meeting points of the prehadron constituents are extracted for each single event in Monte Carlo simulations using the Jetset-part of Pythia. We discuss the implication on the deep inelastic lepton scattering experiments at HERMES as well as on observables in ultra-relativistic heavy ion collisions at RHIC, using Pythia also for modeling the hard part of the interaction.

We investigate hadron formation in deep inelastic lepton scattering on N , Kr and Xe nuclei in the kinematic regime of the HERMES experiment. The elementary electron-nucleon interaction is described within the event generator PYTHIA while a full coupled-channel treatment of the final state interactions is included by means of a BUU transport model. We find a good agreement with the measured charged hadron multiplicity ratio R h M for N and Kr targets by accounting for the deceleration and absorption of the primarily produced particles as well as for the creation of secondary hadrons in the final state interactions.