Bottomonia in the quark-gluon plasma and their production at RHIC and LHC

Abstract

We study the production of bottomonium states in heavy-ion reactions at collider energies available at RHIC and LHC. We employ an earlier constructed rate equation approach which accounts for both suppression and regeneration mechanisms in the quark-gluon plasma (QGP) and hadronization phases of the evolving thermal medium. Our previous predictions utilizing two limiting cases of strong and weak bottomonium binding in the QGP are updated by (i) checking the compatibility of the pertinent spectral functions with lattice-QCD results for euclidean correlators, (ii) adapting the initial conditions of the rate equation by updating bottom-related input cross sections and the charged-particle multiplicity of the fireball, and (iii) converting our calculations into observables as recently measured by the STAR and CMS experiments. Our main findings are a preference for strong Υ binding as well as a significant regeneration component at the LHC.

Aspects of heavy-ion collisions at the LHC

“…The suppression found experimentally is much more pronounced than in the calculation, in particular, for the three more peripheral data points. Other theoretical approaches such as [44][45][46] also find that the Υ(2S ) suppression factor rises towards 1 for peripheral collisions, in contrast with the data.…”

Dissociation of quarkonium in a complex potential

“…Earlier it was thought that a quarkonium state is dissociated when the Debye screening becomes so strong that it inhibits the formation of bound states but nowadays a quarkonium is dissociated at a lower temperature [16,35] even though its binding energy is nonvanishing, rather is overtaken by the Landau-damping induced thermal width [36], obtained from the imaginary part of the potential. Its consequences on heavy quarkonium spectral functions [35,37], perturbative thermal widths [36,38] quarkonia at finite velocity [39], in a T-matrix approach [40,41,42,43,44], and in stochastic real-time dynamics [45] have been studied. Recently the dynamical evolution of the plasma was combined with the real and imaginary parts of the binding energies to estimate the suppression of quarkonium [46] in RHIC and LHC energies.…”

Quarkonia production in the STAR experiment

“…±0.03 −0.13 (syst.). The measured R AA is compared to two model predictions, Strickland and Bozow [27] and Emerick et al [28], that include hot-nuclear-matter effects. The model of Emerick et al takes also into account the CNM effects.…”

“…Figure 5. Left: R dA and R AA as a function of N part for Υ(1S + 2S + 3S ) at |y| < 1 for d+Au (green rectangle), Au+Au (black circles), ( [5]), and U+U (red diamonds) collisions, compared to two model predictions (shaded areas), [27,28]. Right: R dA and R AA vs N part for Υ(1S ) ground state at |y| < 1 for d+Au (green rectangle) and Au+Au (black circles) collisions, ( [5]), compared to different model predictions (shaded area and dashed line), [27,29].…”