Heidelberg 1999 – scientific programme
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T: Teilchenphysik
T 303: Diffraktion 1
T 303.4: Talk
Tuesday, March 16, 1999, 14:45–15:00, TE10
Diffractive vector mesons beyond the s-channel helicity conservation — •I. Ivanov1,2 and N.N. Nikolaev1,3 — 1Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich — 2Novosibirsk University, Novosibirsk, Russia — 3L.D. Landau Inst. for Theor. Phys., Moscow
We derive the full set, and determine the twist, of helicity amplitudes for diffractive production of S and D-wave vector mesons in deep inelastic scattering. For large Q2 all helicity amplitudes but the double spin-flip are calculable within perturbative QCD and are proportional to the gluon structure function of the proton at a similar hard scale. We find a substantial breaking of the s-channel helicity conservation which must persist also in real photoproduction.