Quarkonia Photoproduction at Nucleus Colliders

Exclusive photoproduction of heavy quarkonia in high-energy ultraperipheral ion-ion interactions (γ A → V A, where V = J/ψ, ϒ and the nucleus A remains intact) offers a useful means to constrain the small-x nuclear gluon density. We discuss preliminary results on J/ψ photoproduction in Au-Au collisions at RHIC [D. d'Enterria [PHENIX Collaboration], Proceeds. Quark Matter'05, arXiv:nucl-ex/0601001], as well as full simulation-reconstruction studies of photo-produced ϒ in Pb-Pb interactions at the LHC [D. d'Enterria (ed.) et al. [CMS Collaboration], J. Phys. G. 34 2307 (2007)].