Hot-medium effects on ϒ yields in p-Pb and Pb-Pb collisions

Abstract

The modification of bottomonia yields in Pb–Pb and p–Pb collisions at LHC energies with respect to the expectation from p–p is investigated in a theoretical approach. Dissociation of the ϒ(nS ) and ϒ(nP) states in the hot quark-gluon plasma (QGP) occurs due to screening of the real quark-antiquark potential, collisional damping through the imaginary part of the potential, and gluon-induced dissociation. Reduced feed-down plays a decisive role. Transverse-momentum and centrality-dependent data are well re- produced. In the asymmetric p-Pb system, alterations of the parton density functions in the lead nucleus account for the leading fraction of the modifications in cold nuclear matter (CNM), but the hot-medium effects turn out to be relevant in spite of the small initial spatial extent of the fireball.