Data-driven analysis for the temperature and momentum dependence of the heavy-quark diffusion coefficient in relativistic heavy-ion collisions

Abstract

International audienceBy applying a Bayesian model-to-data analysis, we estimate the temperature and momentum dependence of the heavy quark diffusion coefficient in an improved Langevin framework. The posterior range of the diffusion coefficient is obtained by performing a Markov chain Monte Carlo random walk and calibrating on the experimental data of D-meson RAA and v2 in three different collision systems at the Relativistic Heavy-Ion Collidaer (RHIC) and the Large Hadron Collider (LHC): Au-Au collisions at 200 GeV and Pb-Pb collisions at 2.76 and 5.02 TeV. The spatial diffusion coefficient is found to be consistent with lattice QCD calculations and comparable with other models' estimation. We demonstrate the capability of our improved Langevin model to simultaneously describe the RAA and v2 at both RHIC and the LHC energies, as well as the higher order flow coefficient such as D meson v3. We show that by applying a Bayesian analysis, we are able to quantitatively and systematically study the heavy flavor dynamics in heavy-ion collisions

Transport coefficients from in-medium quarkonium dynamics

“…In the opposite, large time limit, t − t 0 is the largest time scale in the problem. At this point, it is convenient to assume that the chromoelectric correlators appearing in (21) and (22) are, at least approximately, time translation invariant: E a,i (t, 0)E a,i (t , 0) = E a,i (t − t , 0)E a,i (0, 0) . This is the case, for instance, at thermal equilibrium or close to it, if the variation in time of the temperature is slow.…”

Linearized Boltzmann-Langevin model for heavy quark transport in hot and dense QCD matter

“…We now apply the calibrated model to predict observables that have already been measured but were excluded in the calibration (validation) and also predict The shaded region indicates a previous extraction in [21]. Square and dimond symbols are lattice calculations in the static heavy quark limit [19,20]; triangular symbols are lattice calculations with physical charm quark mass [18].…”

“…There are efforts to calculate these transport coefficients in various approaches including lattice QCD [5,6,[13][14][15][16][17][18][19][20]. Our group has taken a complementary approach, using experiment data to calibrate our Langevin based transport model to measured observables and thus extract the transport coefficients directly from data via a Bayesian analysis [21]. The drawback of this approach is that it does not in itself provide a fundamental understanding of the interaction mechanism but can only provide guidance to direct calculations of the transport coefficients in terms of compatibility to experimental observation.…”

“…Blue boxed region is for bottom quarks and red slashed region for charm quarks. The shaded region indicates a previous extraction[21].…”

Open Heavy Flavors in Nuclear Collisions: Theory Overview

“…Another noticeable achievement this year is the application of state of the art Bayesian methods by the Duke group [11] in order to perform data-driven extraction of the diffusion coefficient D s based on an extended set of experimental results. For this purpose, the authors have complemented the pQCD value of D s (T, p) by a non-perturbative part of tunable range in momentum space and of tunable slope as a function of T. The total D s coefficient then enters the energy loss computation, with a radiative component modeled through the higher twist approach.…”