Large-P_T inclusive photoproduction of J/psi in electron-proton collisions at HERA and the EIC

TL;DR

This paper presents a comprehensive calculation of inclusive J/psi photoproduction at high transverse momentum in electron-proton collisions, incorporating novel contributions and schemes, and explores the potential to probe the proton's charm content at the EIC.

Contribution

It introduces the first use of the variable-flavour-number scheme in quarkonium photoproduction and includes a previously ignored QED-induced contribution, enhancing the understanding of J/psi production mechanisms.

Findings

QED-induced contribution dominates at high P_T

J/psi+charm production is observable at the EIC

The EIC can probe the proton's non-perturbative charm content

Abstract

We study the inclusive J/psi production at large transverse momenta at lepton-hadron colliders in the limit when the exchange photon is quasi real, also referred to as photoproduction. Our computation includes the leading-P_T leading-v next-to-leading alpha_s corrections. In particular, we consider the contribution from J/psi plus another charm quark, by employing for the first time in quarkonium photoproduction the variable-flavour-number scheme. We also include a QED-induced contribution via an off-shell photon which remained ignored in the literature and which we show to be the leading contribution at high P_T within the reach of the EIC. In turn, we use our computation of J/psi+charm to demonstrate its observability at the future EIC and the EIC sensitivity to probe the non-perturbative charm content of the proton at high x.