Photonuclear [formula omitted] production at the LHC: Proton-based versus nuclear dipole scattering amplitudes

D Bendova,J Cepila,J.G Contreras,M Matas

doi:10.1016/j.physletb.2021.136306

D Bendova, J Cepila + Show 2 more

Open Access

https://doi.org/10.1016/j.physletb.2021.136306

Copy DOI

Journal: Physics Letters B	Publication Date: Apr 22, 2021
Citations: 19	License type: cc-by

Affiliation: Czech Technical University in Prague

Abstract

The coherent photonuclear production of a J/ψ vector meson at the LHC has been computed using two different sets of solutions of the impact-parameter dependent Balitsky-Kovchegov equation. The nuclear dipole scattering amplitudes are obtained either from (i) solutions for this process off proton targets coupled with a Glauber-Gribov prescription, or (ii) from solutions obtained with an initial condition representing the nucleus. These approaches predict different cross sections, which are compared with existing data from ultra-peripheral collisions at the LHC. The latter approach seems to better describe current measurements. Future LHC data should be precise enough to select one of the two approaches as the correct one.

Highlights

The exclusive photoproduction of a J/ψ vector meson off a hadron has been recognised for many years as a very sensitive probe of the gluonic structure of hadrons in the perturbative regime of quantum chromodynamics (QCD) [1,2]; it has been extensively studied at HERA [3,4]
Many computations predicting the behaviour of this process off nuclear targets start from a description of the process off nucleons, where the parameters of the given model are fixed by HERA data, and apply some form of Glauber formalism to predict the cross sections for photonuclear production
The cross section dσ /dy for the coherent photoproduction of a J/ψ vector meson in Pb–Pb ultra-peripheral collisions (UPC) is shown in Fig. 2 for the LHC

Summary

Introduction

The exclusive photoproduction of a J/ψ vector meson off a hadron has been recognised for many years as a very sensitive probe of the gluonic structure of hadrons in the perturbative regime of quantum chromodynamics (QCD) [1,2]; it has been extensively studied at HERA [3,4]. Many computations predicting the behaviour of this process off nuclear targets start from a description of the process off nucleons, where the parameters of the given model are fixed by HERA data, and apply some form of Glauber formalism to predict the cross sections for photonuclear production. Such an approach has been followed for example in [10,11,12,13]

Results

Discussion

Conclusion