Exclusive rho^0 production in deep inelastic scattering at HERA

TL;DR

This paper reports on the measurement of exclusive rho^0 electroproduction at HERA, analyzing cross sections, angular distributions, and Pomeron trajectory to test QCD-based models in a broad kinematic range.

Contribution

It provides detailed experimental data on rho^0 production, including cross sections and helicity ratios, and compares these results with theoretical predictions, advancing understanding of diffractive processes.

Findings

Cross section increases with W and varies with Q^2

Longitudinal to transverse cross section ratio depends on Q^2

An effective Pomeron trajectory was extracted

Abstract

Exclusive rho^0 electroproduction at HERA has been studied with the ZEUS detector using 120 pb^{-1} of integrated luminosity collected during 1996-2000. The analysis was carried out in the kinematic range of photon virtuality 2 < Q^2 < 160 GeV$^2, and gamma^* p centre-of-mass energy 32 < W < 180 GeV. The results include the Q^2 and W dependence of the gamma^* p --> rho^0 p cross section and the distribution of the squared-four-momentum transfer to the proton. The helicity analysis of the decay-matrix elements of the rho^0 was used to study the ratio of the gamma^* p cross section for longitudinal and transverse photon as a function of Q^2 and W. Finally, an effective Pomeron trajectory was extracted. The results are compared to various theoretical predictions.