Momentum anisotropy effects for quarkonium in a weakly coupled quark-gluon plasma below the melting temperature

Abstract

In the early stages of heavy-ion collisions, the hot QCD matter expands more longitudinally than transversely. This imbalance causes the system to become rapidly colder in the longitudinal direction, and a local momentum anisotropy appears. In this paper, we study the heavy-quarkonium spectrum in the presence of a small plasma anisotropy. We work in the framework of potential nonrelativistic QCD at finite temperature. We inspect arrangements of nonrelativistic and thermal scales complementary to those considered in the literature. In particular, we consider temperatures larger and Debye masses smaller than the binding energy, which is a temperature range relevant for presently running LHC experiments. In this setting, we compute the leading thermal corrections to the binding energy and the thermal width induced by quarkonium gluodissociation.