Bochum 1998 – wissenschaftliches Programm

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HK: Hadronen und Kerne

HK 44: Plenar

HK 44.3: Gruppenbericht

Mittwoch, 18. März 1998, 10:30–11:00, P

Coherence phenomena in deep-inelastic lepton-nucleus scattering — •Gunther Piller — Technische Universität München

The recently completed analysis of deep-inelastic lepton-nucleus scattering experiments at CERN (NMC) and FNAL (E665), together with earlier data from SLAC, provides detailed information on modifications of nuclear structure functions as compared to the structure functions of free nucleons.

Two different kinematical regions, selected by the Bjorken scaling variable x, are of interest in this context. At intermediate values of x, incoherent scattering from individual nucleons in the target dominates, and nuclear effects are commonly understood in terms of nuclear binding and Fermi motion. More significant deviations of nuclear structure functions from those of free nucleons are observed at small values of Bjorken x. Here the coherent scattering from several nucleons in the target dominates and leads to the so-called shadowing effect. Much insight into the basic mechanisms behind coherence phenomena has been gained in recent years.

We review the current understanding of nuclear effects in deep-inelastic lepton scattering and outline implications for nuclear quark and gluon distribution functions. We study the propagation of partons in the nuclear medium. Furthermore we investigate the relationship between nuclear shadowing and diffractive leptoproduction off protons as explored recently at HERA. Finally we sketch possible future investigations of nuclear quark and gluon distribution functions at HERA, HERMES and LHC.