Eur. Phys. J. C (2010) 67: 455-463
https://doi.org/10.1140/epjc/s10052-010-1312-8

Regular Article - Theoretical Physics

Quarkonium plus prompt-photon associated hadroproduction and nuclear shadowing

¹ Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande, Caixa Postal 474, 96201-900, Rio Grande, RS, Brazil
² Centro de Ciências Exatas e Tecnológicas, Universidade Federal do Pampa Campus de Bagé, Rua Carlos Barbosa, 96400-970, Bagé, RS, Brazil

^* e-mail: magnus@if.ufrgs.br

Received: 16 November 2009
Revised: 4 March 2010
Published online: 28 April 2010

Abstract

Quarkonium hadroproduction in association with a photon at high energies provides a probe of the dynamics of the strong interactions as it is dependent on the nuclear gluon distribution. Therefore, it could be used to constrain the behavior of the nuclear gluon distribution in proton–nucleus and nucleus–nucleus collisions. Such processes are useful to single out the magnitude of the shadowing/antishadowing effects in the nuclear parton densities. In this work we investigate the influence of nuclear effects in the production of J/ψ+γ and ϒ+γ and estimate the transverse momentum dependence of the nuclear modification factors. The theoretical framework considered in the J/ψ (ϒ) production associated with a direct photon at the hadron collider is the non-relativistic QCD (NRQCD) factorization formalism.