Differential Distributions for Heavy Flavour Production at HERA
S. Frixione, P. Nason, G. Ridolfi
TL;DR
The paper analyzes heavy flavour production at HERA, focusing on differential distributions in pseudorapidity and transverse momentum for charm and bottom quarks. It employs next-to-leading order QCD calculations for photoproduction and hadroproduction, examining direct and hadronic photon components, intrinsic transverse momentum and fragmentation, and compares results with the HERWIG Monte Carlo. It investigates the potential to constrain photon parton densities and to probe the small-$x$ behavior of the proton gluon density, and provides predictions for bottom production. The study also discusses parameter choices and the relative importance of the point-like and hadronic components, including electroproduction via the Weizsäcker-Williams approach.
Abstract
We compute pseudorapidity and transverse momentum distributions for charm and bottom production at HERA. We examine the effect of next-to-leading order QCD corrections, the effect of possible intrinsic transverse momenta of the incoming partons, and of fragmentation. We compare our results with full Monte Carlo simulation using HERWIG. The importance of the hadronic component of the photon is also studied. We examine the possibility to distinguish among different parametrizations of the photon parton densities using charm production data, and the possibilty to extract information about the small-$x$ behaviour of the gluon density of the proton. We also give a prediction for the transverse momentum and pseudorapidity distributions for bottom production at HERA.