Heavy meson production at HERA

Jan Figiel

doi:10.1051/epjconf/20148104003

Abstract

The copious production of charm mesons at HERA has allowed QCD to be probed in open charm and charm vector meson production. Elastic and proton-dissociatve photoproduction of J / ψ mesons have been measured at HERA. The data are compared to other measurements and the W and t dependences are parametrised using phenomenological fits. The ψ (2 S ) state has also been measured exclusively and the ratio of its production rate to J / ψ mesons presented as a function of the kinematic variables. Inelastic production of J / ψ and ψ (2 S ) mesons gives insight into non-relativistic QCD and final results are presented here. Open charm production has been measured in order to better understand the fragmentation process of charm mesons as well as giving insight into the structure of the proton.

Highlights

Still 7 years after closing HERA ep collider new physical results based on its data are published
In case of charmonium production this is a two-scale process with large J/ψ mass and momentum transfer t and in the leading logarithmic (LL) QCD approximation it can be described by the exchange of a gluon ladder
At large |t| values, the cross section is expected to decrease according to power law

Summary

Introduction

Still 7 years after closing HERA ep collider new physical results based on its data are published. The recent, selected results on heavy meson production at HERA from the H1 and ZEUS experiments are presented and interpreted within the framework of Quantum Chromodynamics

Diffractive charmonium production

Findings

Open charm production