Light vector meson photoproduction at large momentum transfer

We have studied in perturbative QCD all independent helicity amplitudes describing the photoproduction of light vector mesons at large t. We found a new hard production mechanism which is related to the possibility for a real photon to fluctuate into a massless q (q) over bar pair in a chiral-odd spin configuration. Each helicity amplitude is given as a sum of chiral-even contribution (when the helicities of quark and antiquark are antiparallel) and this additional chiral-odd part (where the helicities of quark and antiquark are parallel). All amplitudes are expressed in terms of short distance asymptotics of the light-cone wave functions of vector meson and photon. The chiral-odd contribution is large, it leads to a dominance of the non spin-flip amplitude in a very broad region of intermediately high /t/.