Speaker
Description
Heavy flavor physics in high-energy heavy-ion collisions is a promising and active area to study the `` jet quenching " effects both at the RHIC and the LHC. The recent reported $D^0$ meson radial profiles in jets measured by CMS collaboration provide new experimental constraints on the mechanisms of heavy flavor production in proton-proton collisions and give new insights into the in-medium interaction mechanisms of heavy quarks inside the quark-gluon plasma (QGP). In this talk, we present the first theoretical calculations of the $D^0$ meson radial distributions relative to the jet axis both in p+p and Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV, which show a nice agreement compared to the experimental data. In our work, the in-medium parton propagations are described by a Monte Carlo transport model which uses the next-to-leading order (NLO) plus parton shower (PS) event generator SHERPA as input and includes elastic (collisional) and inelastic (radiative) interaction for heavy quarks as well as light partons. Our simulated results show that, at low $D^0$ $p_T$, the radial distribution shifts to larger radius indicating a strong diffusion effect of charm quarks due to the in-medium interactions, but no significant modification observed at high $D^0$ $p_T$, which are consistent with the experimental data. In the further study, we estimate the net effect on the charm diffusion from collisional and radiative mechanism, and demonstrate the $p_T$ dependence of this diffusion effect. We find that collisional process has significant effects at low $p_T$, especially dominates at $0-5$ GeV, and the radiative process has a non-zero effect even at high $p_T\sim 50$ GeV. The total diffusion effect decreases with $D^0$ $p_T$ which explains the significant modification at low $D^0$ meson $p_T$ observed in experiment. Besides, for unit energy loss, the collisional interaction shows much stronger angular deviation than radiative interaction indicating an essential difference between these two mechanisms. For completeness, we also present the calculations of $D^0$ meson radial distribution in jets in p+p and $0-10\%$ Au+Au collisions at $200$ GeV, and estimate the nuclear modification factor of charm jet in central Au+Au collisions at $200$ GeV and central Pb+Pb collisions at $5.02$ TeV.
