Exclusive production of ρ meson in gamma-proton collisions: dσ /dt and the role of helicity flip processes

We calculate the differential cross section d sigma/dt for the diffractive photoproduction process gamma p -> rho p and compare to recent data extracted by the CMS collaboration from ultraperipheral proton-lead collisions. Our model is based on two-gluon exchange in the nonperturbative domain. We take into account both helicity conserving and often neglected helicity-flip amplitudes in the gamma -> V transition. The latter can contribute at finite t. The shape of the differential cross section as well as the role of helicity flip processes is strongly related to the dependence of the unintegrated gluon distribution on transverse momenta in the nonperturbative region. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.

Automated summary

We calculate the differential cross section for diffractive photoproduction process gamma p -> rho p and compare it with recent data from ultraperipheral proton-lead collisions. Our model considers two-gluon exchange in the nonperturbative domain, including often neglected helicity-flip amplitudes. The shape of the differential cross section and the role of helicity flip processes are influenced by the unintegrated gluon distribution in the nonperturbative region.