Bottomium suppression in PbPb collisions at LHC energies

TL;DR

This paper refines a model for Upsilon meson suppression in quark-gluon plasma created in PbPb collisions at LHC energies, incorporating various physical effects and comparing with experimental data.

Contribution

It introduces an improved suppression model accounting for gluodissociation, damping, screening, and decay cascades, with hydrodynamical effects and finite momentum considerations.

Findings

Model agrees well with CMS and ALICE data for central collisions.

Suppression of excited states is weaker in peripheral collisions.

Predictions are made for higher energy collisions at 5.52 TeV.

Abstract

We substantially refine our previously developed model for the suppression of Upsilon mesons in the quark-gluon plasma (QGP) formed in 2.76 TeV PbPb collisions at the LHC. It accounts for gluodissociation of the six bottomium states Y(nS), chi_b(nP) with n = 1,2,3, collisional damping of these states as described in a complex potential, screening of the real part of the potential, and the subsequent decay cascade. In the hydrodynamical calculation of the expanding fireball, we take into account the effect of transverse expansion on the suppression factors, and finite transverse momenta of the heavy mesons in the medium. The running of the coupling is considered, resulting in larger gluodissociation decay widths. The initial central temperature is found to be 550 MeV at 0.1 fm/c. Our results are in good agreement with recent centrality-dependent CMS and ALICE data. The calculated suppression of the excited states relative to the ground state Y(1S) is not strong enough in peripheral collisions. Additional mechanisms are discussed. Predictions for 5.52 TeV are made.