Nonlinearity of vacuum reggeons and exclusive diffractive production of vector mesons at HERA

TL;DR

This paper models exclusive vector meson production at HERA using a Regge-eikonal scheme with nonlinear trajectories, successfully describing experimental data and highlighting the roles of soft and hard pomerons.

Contribution

It introduces a phenomenological model with nonlinear Regge trajectories that explicitly incorporates QCD asymptotics to describe vector meson production at HERA.

Findings

Model accurately reproduces experimental angular distributions and cross-sections.

Soft and hard pomerons are essential for describing different meson production regimes.

Nonlinear trajectories improve the theoretical description of high-energy diffractive processes.

Abstract

The processes of exclusive photo- and electroproduction of vector mesons $\rho^0$(770), $\phi$(1020) and $J/\psi$(3096) at collision energies $30 GeV<W<300 GeV$ and transferred momenta squared $0<-t<2 GeV^2$ are considered in the framework of a phenomenological Regge-eikonal scheme with nonlinear Regge trajectories in which their QCD asymptotic behavior is taken into account explicitly. By comparison of available experimental data from ZEUS and H1 Collaborations with the model predictions it is demonstrated that corresponding angular distributions and integrated cross-sections in the above-mentioned kinematical range can be quantitatively described with use of two $C$-even vacuum Regge trajectories. These are the "soft" pomeron dominating the high energy reactions without a hard scale and the "hard" pomeron giving an essential contribution to photo- and electroproduction of heavy vector mesons and deeply virtual electroproduction of light vector mesons.