Heavy Flavour Production, QCD, and the Quark-Photon Coupling

The example of beauty photoproduction at HERA is taken as a starting point for the discussion of the uncertainties of NLO QCD predictions. As a result of a phenomenological study of the QCD scale dependence in NLO and NNLO predictions, a modification of the “default” QCD scale choice is advocated. The resulting predictions are confronted with heavy flavour and jet cross section measurements in ep, , and AA collisions. Improved agreement is found. Turning to heavy flavour production in γγ collisions, experimental constraints on potential nonperturbative QCD corrections to the QED photon-quark coupling are investigated. Surprisingly, these are found to be very weak, such that large corrections of this kind are experimentally not excluded. Improved dedicated measurements are proposed.