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HK: Hadronen und Kerne
HK 33: Structure of Baryons, Mesons V, Theory
HK 33.1: Group Report
Tuesday, March 17, 1998, 14:00–14:30, J
Hard Exclusive Leptoproduction of Mesons — •Thomas Weigl, Lech Mankiewicz, and Gunther Piller — Technische Universität München, Physik Department T39
Detailed insights into the quark-gluon substructure of nucleons can be obtained from hard exclusive leptoproduction of pseudoscalar and vector mesons. Here new kinds of observables — nonforward parton distribution functions — are probed.
We present an analysis of leading order QCD amplitudes for hard exclusive meson production. After reviewing some general features of nonforward nucleon matrix elements of twist-2 QCD string operators, we propose a phenomenological model for quark and gluon nonforward distribution functions. The corresponding QCD evolution equations are solved in the leading logarithmic approximation. We derive explicit expressions for hard exclusive π0, η, neutral and charged vector meson production amplitudes and discuss general features of the corresponding cross-sections in the kinematic domain of current fixed target and collider experiments.