Speaker
Description
Heavy flavor production provides a unique probe for studying the transport properties of the quark-gluon plasma (QGP) formed in high-energy nuclear collisions. Experimental observables like the nuclear modification factor $R_{AA}$ and elliptic anisotropy $v_{2}$ of heavy flavor mesons are sensitive to the heavy quark diffusion coefficient. There now exist an extensive set of such measurements, which allow a data-driven extraction of this coefficient. In this work[1], we make such an attempt within our recently developed heavy quark transport modeling framework (Langevin-transport with Gluon Radiation, LGR[2-4]). A question of particular interest is the temperature dependence of the diffusion coefficient, for which we test a wide range of possibilities and draw constraints by comparing relevant charm meson data with model results. We find that a relatively strong increase of diffusion coefficient from crossover temperature $T_{c}$ toward high temperature is preferred by data.
Furthermore, We have made predictions for Bottom meson observables down to the low momentum region for further experimental tests[5]. It is found that our calculations can describe simultaneously $R_{AA}$ and $v_{2}$ data for the prompt and non-prompt $D^{0}$ mesons in central ($0-10\%$) and semi-central ($30-50\%$) Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02~{\rm TeV}$. Recently, we employ a soft-hard factorized model, which combines a thermal perturbative description of soft scatterings and a perturbative QCD-based calculation for hard collisions, we check the energy and temperature dependence of the heavy quark diffusion coefficients in Langevin dynamics[6]. With the parameter-optimized model, we find that a small value of the spatial diffusion coefficient at transition temperature is preferred by data $2\pi TD_{s}(T_{c}) \simeq 6$.
[1] S. Li and J. F. Liao, Data-driven extraction of heavy-quark diffusion in quark-gluon plasma, Eur. Phys. J. C, 80, 671 (2020)
[2] S. Li, C. W. Wang, X. B. Yuan, and S. Q. Feng, Production of open-charm mesons in relativistic heavy-ion collisions, Phys. Rev. C, 98, 014909 (2018)
[3] S. Li and C. W. Wang, Charm-strange meson production in ultrarelativistic heavy-ion collisions at energies available at the CERN Large Hadron Collider, Phys. Rev. C, 98, 034914 (2018)
[4] S. Li, C. W. Wang, R. Z. Wan, and J. F. Liao, Probing the transport properties of quark-gluon plasma via heavy-flavor Boltzmann and Langevin dynamics, Phys. Rev. C, 99, 054909 (2019)
[5] S. Li, W. Xiong, and R. Z. Wan, Relativistic Langevin dynamics: charm versus beauty, Eur. Phys. J. C, 80, 1113 (2020)
[6] S. Li, F. Sun, W. Xie, W. Xiong, Langevin dynamics of heavy quarks in a soft-hard factorized approach, Eur. Phys. J. C, 81, 536 (2021)
