Bayesian Inference of Heavy-Quark Dissipation and Jet Transport Parameters from D-Meson observables in heavy-ion collisions at the LHC energies

TL;DR

The paper addresses how heavy-quark transport in the QGP can be constrained from D-meson observables by jointly inferring the temperature-dependent heavy-quark diffusion $2\pi T\mathcal{D}_s$ and jet transport $\hat{q}/T^3$. It uses a unified Langevin framework that includes collisional and radiative energy loss and a coalescence-plus-fragmentation hadronization scheme, with a hierarchical Bayesian inference driven by $R_{AA}$, $v_2$, $dN/dp_T$, and $D_s^+/D^0$ data. Key findings show that 30--50% centrality data provide tighter constraints, the inferred $2\pi T\mathcal{D}_s$ near $T_c$ agrees with lattice QCD in slope, and the temperature dependence of $\hat{q}/T^3$ aligns with global light-flavor fits, while the ratio $\hat{q}/\kappa$ is below the naive estimate and exhibits nontrivial temperature behavior. Overall, the work establishes a data-driven link between heavy-quark diffusion and jet quenching, offering a refined transport baseline for hadronization and informing comparisons with theory across the QGP phase diagram.

Abstract

We perform the first simultaneous Bayesian inference of the temperature-dependent heavy-quark spatial diffusion coefficient $2πT\mathcal{D}_s$ and the scaled jet transport coefficient $\hat{q}/T^3$ in the quark-gluon plasma, utilizing $D$-meson nuclear modification factor $R_\text{AA}$ and elliptic flow $v_2$ data from Pb-Pb collisions at $\sqrt{s_\text{NN}} = 5.02\ \text{TeV}$. The analysis employs a unified improved Langevin transport model that incorporates both collisional and radiative energy loss, followed by coalescence plus fragmentation hadronization. The posterior distributions of the parameters of $\hat{q}/T^3$ and those of $2πT\mathcal{D}_s$ are well constrained, and compared with the results of theoretical models or other experimental data extraction, respectively. The $30-50\%$ centrality data provide significantly stronger constraints than the $0-10\%$ data. The extracted ratio $\hat{q}/κ$ between the quark jet transport and heavy-quark diffusion coefficients exhibits a non-monotonic temperature dependence, deviating from the value $2$ estimated from the definition, with a value interval spanning 0.25--0.8 corresponding to the mean values of the inferred parameters. This work establishes a data-driven quantitative relationship between these two fundamental transport properties in the same observables, offering crucial insight into their interplay in the strongly coupled medium.

Figures (5)

• Figure 1: Posterior distributions (diagonal panels) and pairwise correlations (off-diagonal panels) of the model parameters $\hat{q}_0/T_0^3$, $\hat{q}_\mathrm{c}/T_\mathrm{c}^3$, $k_{\rm 2\pi T \mathcal{D}_s}$, and $b_{\rm 2\pi T \mathcal{D}_s}$ for Pb+Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. All panels display results with 95% credibility intervals. Combined analysis of 0--10% and 30--50% centrality classes.
• Figure 2: Bayesian-inferred temperature dependence of $2\pi T\mathcal{D}_s$ as a function of $T/T_c$, comparing results obtained from the 0-10% Pb-Pb collision system (blue), the 30-50% centrality class (green), and their combined analysis (orange). The shaded bands indicate the 95% credibility regions, respectively. The model-to-Data fitting result of the ALICE Collaboration is presented at $T=T_c$ with large theoretical uncertainty ALICE:2021rxa, the 0 flavor, and the 2+1 flavor lattice QCD results Altenkort:2023oms are also plotted.
• Figure 3: The scaled jet transport coefficient $\hat{q}/T^3$ as a function of the medium temperature $T$ obtained from the 0-10$\%$ Pb+Pb collision system (blue), the 30-50$\%$ centrality class (green), and their combined analysis (orange), compared to results from a global fitting to experimental data of large $p_T$ light hadron at LHC (black-dashed line) Xie:2024xbn, JETSCAPE (black shadow) JETSCAPE:2021ehl and the JET Collaboration (red dots) JET:2013cls. All results are presented using mean values of the inferred parameters $\hat{q}_0/T^3$ and $\hat{q}_c/T^3$ along with 95% credibility intervals.
• Figure 4: The ratio $\hat{q}/\kappa$ as a function of the medium temperature $T$ obtained from the 0-10$\%$ Pb+Pb collision system (blue), the 30-50$\%$ centrality class (green), and their combined analysis (orange). The results are presented using mean values of the inferred parameters along with 95$\%$ credibility regions.
• Figure 5: Prior and Posterior predictions of observables vs. data from ALICE and CMS with 95% credibility intervals.