Is There Window for a "Supersoft" Pomeron in J/  Photoproduction at Low Energy?

Abstract

The low energy J/ψ photoproduction cross-section has been studied using the Pomeron model. To account for the discrepancy between experimental data and predictions of conventional models, i.e. the sum of the soft Pomeron with intercept 1.08 and the hard Pomeron with intercept 1.418, a Regge trajectory associated with a scalar meson (f, a) exchange, which we call a "supersoft" Pomeron, is introduced. To distinguish the conventional model from that with this new additional Pomeron, proposed observations related to other polarization observables in upcoming polarized experiments are discussed.

On a possible manifestation of f1 trajectory in J/ψ photoproduction

“…These trajectories with positive and negative signature are important in the near-threshold region though their contribution decreases with energy. But for description of the J/ψ photoproduction for all energy regions, one must take into account all of the above trajectories: Pomeron, hard Reggeon and mesonic (supersoft) trajectories [10].The Pomeron and "hard" Reggeon which are dominant at high energy on the phenomenological level are described by the effective "C = +1 photon" exchange which leads to similar spin observables for all components typical for the amplitude with t -channel natural parity exchange. However, so far the study of the unnatural parity exchange trajectories at high energy has not been done widely.…”

“…These trajectories with positive and negative signature are important in the near-threshold region though their contribution decreases with energy. But for description of the J/ψ photoproduction for all energy regions, one must take into account all of the above trajectories: Pomeron, hard Reggeon and mesonic (supersoft) trajectories [10].…”