Evidence for the flavor singlet axial anomaly related effects in φ-meson electromagnetic production at large momentum transfers

The gluonic contributions to the conventional PCAC formulas due to flavor singlet axial anomaly have been instrumental in explaining the mass of the η′ and providing a plausible explanation for solving the spin crisis. We show that they also play an important role in the description of photo- and electroproduction of vector mesons at low energy and high momentum transfers. We calculate the contributions of this type to φ-meson electromagnetic production in a model, which contains also a soft pomeron, and find agreement with recent CLAS data.