Diffractive photoproduction of ρ mesons with large momentum transfer at HERA

Le résumé fourni par la source

The diffractive photoproduction of ρ mesons, e p → e ρ Y , with large momentum transfer squared at the proton vertex, |t|, is studied with the H1 detector at HERA using an integrated luminosity of 20.1 pb −1 . The photon–proton centre of mass energy spans the range 75 < W < 95 GeV , the photon virtuality is restricted to Q 2 < 0.01 GeV 2 and the mass M Y of the proton remnant is below 5 GeV. The t dependence of the cross section is measured for the range 1.5 < | t | < 10.0 GeV 2 and is well described by a power law, d σ / d | t | ∝ | t | − n . The spin density matrix elements, which provide information on the helicity structure of the interaction, are extracted using measurements of angular distributions of the ρ decay products. The data indicate a violation of s -channel helicity conservation, with contributions from both single and double helicity-flip being observed. The results are compared to the predictions of perturbative QCD models.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.