Investigation of suppression of $\Upsilon(nS)$ in relativistic heavy-ion collisions at RHIC and LHC energies

TL;DR

This study models the suppression of $Upsilon(nS)$ states in heavy-ion collisions at RHIC and LHC energies to understand quark-gluon plasma properties, using hydrodynamic simulations and thermal width calculations.

Contribution

It introduces a comprehensive model combining hydrodynamics and thermal width calculations to analyze $Upsilon(nS)$ suppression across different collision energies and geometries.

Findings

Model describes $Upsilon(nS)$ suppression at 5.02 TeV and 200 GeV for some states.

Underestimates $Upsilon(1S)$ suppression at lower energy.

Nuclear absorption may explain discrepancies.

Abstract

The primary purpose of studying quarkonium production in relativistic heavy-ion collisions is to understand the properties of the quark-gluon plasma. At various collision systems, measurements of quarkonium states of different binding energies, such as $\Upsilon(nS)$, can provide comprehensive information. A model study has been performed to investigate the modification of $\Upsilon(nS)$ production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV and Au-Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV. The Monte-Carlo simulation study is performed with a publicly available hydrodynamic simulation package for the quark-gluon plasma medium and a theoretical calculation of temperature-dependent thermal width of $\Upsilon(nS)$ considering the gluo-dissociation and inelastic parton scattering for dissociation inside the medium. In addition, we perform a systematic study with different descriptions of initial collision geometry and formation time of $\Upsilon(nS)$ to investigate their impacts on yield modification. The model calculation with a varied parameter set can describe the experimental data of $\Upsilon(nS)$ in Pb-Pb collisions at 5.02 TeV and $\Upsilon(2S)$ in Au-Au collisions at 200 GeV but underestimates the modification of $\Upsilon(1S)$ at the lower collision energy. The nuclear absorption mechanism is explored to understand the discrepancy between the data and simulation.