Elastic Vector Meson Production at HERA

TL;DR

This paper presents new measurements of elastic vector meson production at HERA, revealing insights into the underlying physics, including the independence from photon polarization and the non-universality of the Pomeron trajectory.

Contribution

It provides the first detailed analysis of elastic VM cross-sections and trajectory behavior, highlighting differences from universal models and soft physics indications.

Findings

Elastic VM production is independent of photon polarization.

Non-zero shrinkage observed in J/psi photoproduction suggests soft physics.

Data do not support a universal Pomeron trajectory.

Abstract

The H1 and ZEUS Collaborations report new results on elastic VM cross-section and trajectory determination. Elastic VM production appears to be independent of the photon polarization. The presence of non-zero shrinkage in the photoproduction of J/psi indicates the presence of soft physics. Accumulated data do not accommodate a universal Pomeron trajectory. The steepness of the x dependence of elastic VM production with changing Q^2+M_V^2 is similar to that of F_2 with changing Q^2.