Heavy Quark Production and Spectroscopy at HERA

TL;DR

This paper reviews heavy quark production and spectroscopy at HERA, including measurements of charm and beauty quark states, comparisons with QCD predictions, and observations of excited mesons, highlighting discrepancies in beauty production rates.

Contribution

It provides new measurements of charm and beauty production, observes excited charm mesons, and compares experimental results with QCD predictions, revealing higher-than-expected beauty cross sections.

Findings

Charm meson resonances D^*, D^0, D_s observed and rates extracted.

Excited charm mesons D^0_1(2420), D^{*0}_2(2460), D^{+-}_{s1}(2536) observed.

Beauty production cross sections exceed next-to-leading order QCD predictions.

Abstract

Production of final states containing open charm and beauty quarks at HERA is reviewed. Photoproduction (PHP) of the charm meson resonances D^*, D^0 and D_s, as well as D^* production in the deep inelastic scattering (DIS) regime, are measured and compared to QCD predictions. The excited charm mesons D^0_1(2420), D^{*0}_2(2460) and D^{+-}_{s1}(2536) have been observed and the rates of charm quarks hadronising to these mesons were extracted. A search for radially excited charm mesons has been performed. PHP and DIS beauty cross sections are higher than expected in next-to-leading order QCD.