Langevin dynamics of heavy quarks in a soft-hard factorized approach

TL;DR

This paper develops a combined soft-hard factorized Langevin model to study heavy quark diffusion in quark-gluon plasma, successfully describing experimental data and making predictions for future measurements.

Contribution

It introduces a novel soft-hard factorized approach for Langevin dynamics of heavy quarks, integrating thermal and perturbative QCD descriptions, and fits parameters to experimental data.

Findings

Small spatial diffusion coefficient at transition temperature ($2 extpi TD_{s}(T_{c}) \simeq 6$) is preferred by data.

Model accurately describes $D^{0}$ $R_{ m AA}$ and $v_{2}$ at low $p_T$ in Pb--Pb collisions at different energies.

Predictions made for non-prompt $D^{0}$ mesons at low momentum for future experiments.

Abstract

By utilizing a soft-hard factorized model, which combines a thermal perturbative description of soft scatterings and a perturbative QCD-based calculation for hard collisions, we study the energy and temperature dependence of the heavy quark diffusion coefficients in Langevin dynamics. The adjustable parameters are fixed from the comprehensive model-data comparison. We find that a small value of the spatial diffusion coefficient at transition temperature is preferred by data $2\pi TD_{s}(T_{c}) \simeq 6$. With the parameter-optimized model, we are able to describe simultaneously the prompt $D^{0}$ $R_{\rm AA}$ and $v_{2}$ data at $p_{\rm T}\le8$ GeV in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ and $\sqrt{s_{\rm NN}}=5.02$ TeV. We also make predictions for non-prompt $D^{0}$ meson for future experimental tests down to the low momentum region.