An Investigation of the Hard Contribution to phi Photoproduction

TL;DR

This paper explores the potential significant role of hard perturbative QCD processes in phi photoproduction, demonstrating that a combination of soft and hard contributions aligns well with experimental data and suggests a smooth transition in production mechanisms.

Contribution

It introduces a combined soft and hard QCD model for phi photoproduction and provides predictions for higher energy regimes, highlighting a gradual transition in production mechanisms.

Findings

Coherent sum of pQCD and soft Pomeron explains experimental data.

Transition from soft to hard photoproduction is smooth and gradual.

Predictions made for higher energy experiments at HERA.

Abstract

We investigate the possibility that the process of phi photoproduction may have a significant hard perturbative QCD component. This suggestion is based on a study of the energy dependence of the forward phi photoproduction cross section followed by a calculation where we show that a coherent sum of the pQCD and conventional soft Pomeron contributions provides an excellent reproduction of the experimental data. Our results suggest that the transition from the predominantly soft photoproduction of light rho and omega vector mesons to the predominantly hard photoproduction of heavy J/psi and upsilon is smooth and gradual, similar to the transition observed in deep inelastic scattering studies of the proton structure function in the small x limit. Our predictions for higher HERA energies are presented.