Enlighting the transverse structure of the proton via double parton scattering in photon-induced interactions

TL;DR

This paper investigates double parton scattering in photon-proton interactions, proposing methods to extract information on the proton's transverse structure by analyzing DPS contributions in photoproduction processes.

Contribution

It introduces a model to compute the effective cross-section for DPS in photon-proton interactions and suggests how measuring photon virtuality can reveal proton transverse structure.

Findings

DPS contributes significantly to four-jet photoproduction at HERA.

Measuring photon virtuality can provide insights into the proton's transverse parton distribution.

Lower limits on luminosity needed for experimental observation are established.

Abstract

In the present paper we address double parton scattering (DPS) in quasi-real photon-proton interactions. By using electromagnetic and hadronic models of the photon light cone wave functions, we compute the so-called effective cross-section, $\sigma_{eff}^{\gamma p}$ which allows us to calculate the DPS contribution to these processes under dedicated assumptions. In particular, for the four-jet photoproduction in HERA kinematics we found a sizeable DPS contribution. We show that if the photon virtuality $Q^2$ could be measured and thus the dependence of $\sigma_{eff}^{\gamma p}$ on such a parameter exposed, information on the transverse distance between partons active in proton could be extracted. To this aim, we set lower limits on the integrated luminosity needed to observe such an effect which would allow the extraction of novel information on the proton structure.