# Bottomonium Continuous Production from Unequilibrium Bottom Quarks in Ultrarelativistic Heavy Ion Collisions

## TL;DR

This paper models bottomonium production in heavy ion collisions by combining bottom quark dynamics with medium effects, revealing significant regeneration of $
S$ states in central collisions and exploring the impact of bottom quark thermalization.

## Contribution

It introduces a comprehensive framework using Langevin dynamics and lattice-based potentials to study bottomonium regeneration and suppression in quark-gluon plasma.

## Key findings

- Significant $
S$ regeneration in central Pb-Pb collisions at 5.02 TeV.
- Regeneration is less prominent in minimum bias centrality.
- The study links bottomonium regeneration to bottom quark energy loss.

## Abstract

We employ the Langevin equation and Wigner function to describe the bottom equark dynamical evolutions and their formation into a bound state in the expanding Quark Gluon Plasma (QGP). The additional suppressions from parton inelastic scatterings are supplemented in the regenerated bottomonium. Hot medium modifications on $\Upsilon(1S)$ properties are studied consistently by taking the bottomonium potential to be the color-screened potential from Lattice results, which affects both $\Upsilon(1S)$ regeneration and dissociation rates. Finally, we calculated the $\Upsilon(1S)$ nuclear modification factor $R_{AA}^{\rm rege}$ from bottom quark combination with different diffusion coefficients in Langevin equation, representing different thermalization of bottom quarks. In the central Pb-Pb collisions (b=0) at $\sqrt{s_{NN}}=5.02$ TeV, we find a non-negligible $\Upsilon(1S)$ regeneration, and it is small in the minimum bias centrality. The connections between bottomonium regeneration and bottom quark energy loss in the heavy ion collisions are also discussed.