Photoproduction of ηcγ pairs in the CGC framework

Abstract

In this paper we analyzed the exclusive photoproduction of ηcγ pairs in the color glass condensate framework. We found that the cross section of this process is sensitive only to the forward dipole scattering amplitude, and thus could be used as a new tool for analysis of this fundamental nonperturbative object. Using the phenomenological parametrizations of this object, we estimated numerically the production cross section and counting rates in the kinematics of the ongoing and forthcoming experiments at LHC and future Electron Ion Collider. We found that the cross section is sufficiently large for dedicated experimental study. We also estimated the role of this process as a potential background to ηc photoproduction, which is conventionally considered as a gateway for studies of odderons. We found that the contribution of ηcγ (with undetected photon) is on par with expected contributions of odderons in the kinematics of small momentum transfer |t|≲1 GeV2, though decreases rapidly at larger |t|. Finally, we also calculated the feeddown contribution (from radiative decays of other charmonia) and found that a sizable correction comes from J/ψ→ηcγ decays. This contribution remains pronounced even at relatively large |t| and potentially can impose constraint on detectability of odderons via ηc photoproduction. Published by the American Physical Society 2025