Gluonic effects in vector meson photoproduction at large momentum transfers

Nonperturbative QCD mechanisms are of fundamental importance in strong interaction physics. In particular, the flavor singlet axial anomaly leads to a gluonic pole mechanism which has been shown to explain the η′ mass, violations of the OZI rule and more recently the proton spin. We analyze under which conditions the interaction derived from the gluonic pole exchange might explain the high momentum transfer behavior of the photoproduction cross sections of vector mesons at JLab energies. We provide therefore additional support to our scenario in which nonperturbative QCD mechanisms are relevant for the interpretation of the data.