Eur. Phys. J. C (2015) 75: 64
https://doi.org/10.1140/epjc/s10052-015-3296-x

Regular Article - Theoretical Physics

Photon–jet cross sections in deep-inelastic scattering

¹ LAPTh, Université de Savoie, CNRS, BP 110, Chemin de Bellevue, 74941, Annecy-le-Vieux Cedex, France
² Laboratoire de Physique Théorique, UMR 8627 du CNRS, Université Paris-Sud, Bâtiment 210, 91405, Orsay Cedex, France

^* e-mail: patrick.aurenche@lapth.cnrs.fr

Received: 19 November 2014
Accepted: 28 January 2015
Published online: 10 February 2015

Abstract

We present the complete next-to-leading order calculation of isolated prompt photon production in association with a jet in deep-inelastic scattering. The calculation involves, direct, resolved, and fragmentation contributions. It is shown that defining the transverse momenta in the proton virtual-photon frame (CM), as usually done, or in the laboratory frame, as done in some experiments, is not equivalent and leads to important differences concerning the perturbative approach. In fact, using the latter frame may preclude, under certain conditions, the calculation of the next-to-leading order correction to the important resolved component. A comparison with the latest ZEUS data is performed and good agreement is found in the perturbatively stable regions.