Sequential regeneration of charmonia in heavy-ion collisions

We investigate the production of psi(2S) in nuclear collisions at RHIC and LHC energies. We first address charmonium production in 200 GeV d-Au collisions at RHIC; the strong suppression of psi' mesons observed in these reactions indicates mechanisms beyond initial cold nuclear matter effects. We find that a more complete treatment of hadronic dissociation reactions leads to appreciable psi' suppression in the thermal medium of an expanding fireball background for d-Au collisions. When implementing updated hadronic reaction rates into a fireball for 2.76 TeV Pb-Pb collisions at LHC, the regeneration of psi' mesons occurs significantly later than for J/psi's. Despite a smaller total number of regenerated psi', the stronger radial flow at their time of production induces a marked enhancement of their R-AA relative to J/psi's in a transverse-momentum range of pt similar or equal to 3-6 GeV. We explore the consequences and uncertainties of this sequential regeneration mechanism on the R-AA double ratio and find that it can reproduce the trends observed in recent CMS data. (C) 2015 Elsevier B.V. All rights reserved.