Bottomonium suppression in PbPb collision at energies available at the CERN large hadron collider

TL;DR

This paper presents an advanced theoretical framework for bottomonium suppression in heavy-ion collisions at LHC energies, incorporating improved medium evolution modeling, updated cold nuclear matter effects, and recombination processes, achieving good agreement with experimental data.

Contribution

The work introduces a comprehensive, improved formalism for bottomonium suppression that includes detailed medium evolution, updated shadowing effects, and recombination, extending previous models.

Findings

Good agreement with LHC data for $mbda_{AA}$ and $R_{AA}$

Dependence of suppression on centrality, transverse momentum, and rapidity

Enhanced understanding of cold nuclear matter effects at LHC energies

Abstract

We had been gradually working towards building a comprehensive quarkonia suppression formalism to explain all 3 dependencies of quarkonium suppression obtained from heavy-ion collision experiments. We present here the improved version of quarkonia suppression framework. It assumes bottomonia produced in the early stage which dissociates due to color screening, gluonic dissociation, and collisional damping in addition to the shadowing as an initial state effect. The QGP medium formed in the collisions is assumed to evolve under ($3+1$)-dimensional relativistic viscous hydrodynamics which is modeled using ECHO-QGP. This replaces the Bjorken's hydrodynamics which we had used in our earlier work where we determined the centrality and transverse momentum dependent suppression. The correlated bottom quark and bottom anti-quark could recombine in the plasma. A rate equation is employed, whose solution gives the final number of bottomonium after dissociation and recombination under $(3+1)$-dimensional expansion of the QGP medium. The Shadowing effect, which is the dominant Cold Nuclear Matter effect at LHC energies, has now been modified by employing the most recent parton distribution functions obtained from CT14 global analysis and shadowing factors from EPPS16. Using this improved formalism we determine the centrality, transverse momentum, and rapidity, dependencies of bottomonium suppression for $\Upsilon(1S)$, and $\Upsilon(2S)$ at the LHC's energies of $2.76$ TeV and $5.02$ TeV. We find a fairly good agreement between theoretically calculated survival probability and the measured nuclear modification factor($R_{AA}$) at the two energies.