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

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.