Köln 2004 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 47: Heavy Ions V
HK 47.2: Gruppenbericht
Donnerstag, 11. März 2004, 17:00–17:30, E
Color dipoles and the saturation of nuclear partons — •Wolfgang Schäfer1, Igor P. Ivanov2, Nikolai N. Nikolaev1,3, Bronislav G. Zakharov3, and Vladimir R. Zoller4 — 1IKP, FZ-Jülich — 2Sobolev Inst. Math., Novosibirsk — 3L.D. Landau Inst., Moscow — 4ITEP, Moscow
The treatment of hard processes in high energy nuclear collisions requires an understanding of the parton distributions in energetic Lorentz–contracted nuclei. Already at RHIC energies and even more so at LHC, the gluon density is of special importance. We present an overview of recent developments in the color dipole approach to small-x processes. Here one has to consider the propagation of multiparton systems at fixed impact parameters through the nucleus, which becomes a coupled channel problem in the color space of the partonic system. A special focus will be on the factorization properties of various observables. We discuss the extension of the so–called kt-factorization to nuclear processes. The major difference to reactions on the free nucleon is the opacity(strong absorption)of heavy nuclei, which leads to the saturation of nuclear partons and the emergence of a new hard scale, the saturation scale. We investigate the impact of saturation on a number of observables such as dijet production and their azimuthal decorrelation, high mass diffraction, deep inelastic diffractive vector mesons and their helicity content, as well as heavy quark pair and minijet production in nuclear collisions.