Inclusive jet cross sections and dijet correlations in $D^{*\pm}$ photoproduction at HERA

TL;DR

This paper measures inclusive jet cross sections and dijet correlations in $D^*$ photoproduction at HERA, comparing results with NLO QCD calculations and Monte Carlo models, finding overall good agreement with some discrepancies in higher-order regions.

Contribution

First detailed measurement of jet cross sections in $D^*$ photoproduction at HERA, with comprehensive comparison to NLO QCD and MC models, highlighting areas for theoretical improvement.

Findings

Good agreement between data and NLO QCD in most regions.

MC models better describe the shape of the cross sections.

Discrepancies observed where higher-order contributions are significant.

Abstract

Inclusive jet cross sections in photoproduction for events containing a $D^*$ meson have been measured with the ZEUS detector at HERA using an integrated luminosity of $78.6 {\rm pb}^{-1}$. The events were required to have a virtuality of the incoming photon, $Q^2$, of less than 1 GeV$^2$, and a photon-proton centre-of-mass energy in the range $130<W_{\gamma p}<280 {\rm GeV}$. The measurements are compared with next-to-leading-order (NLO) QCD calculations. Good agreement is found with the NLO calculations over most of the measured kinematic region. Requiring a second jet in the event allowed a more detailed comparison with QCD calculations. The measured dijet cross sections are also compared to Monte Carlo (MC) models which incorporate leading-order matrix elements followed by parton showers and hadronisation. The NLO QCD predictions are in general agreement with the data although differences have been isolated to regions where contributions from higher orders are expected to be significant. The MC models give a better description than the NLO predictions of the shape of the measured cross sections.