High Energy Physics Seminar: Dr. Shanshan Cao, Duke Univeristy
Title: Heavy Flavor Dynamics in Relativistic Heavy-ion Collisions
Abstract: Heavy flavor hadrons serve as valuable probes of the transport properties of the quark-gluon plasma (QGP) created in relativistic heavy-ion collisions. We introduce a comprehensive framework that describes the full-time evolution of heavy flavor in heavy-ion collisions, including its initial production, in-medium evolution inside the QGP matter, hadronization process from heavy quarks to their respective mesonic bound states and the subsequent interactions between heavy mesons and the hadron gas.
The in-medium energy loss of heavy quark is studied within the framework of a Langevin equation coupled to hydrodynamic models that simulate the space-time evolution of the hot and dense QGP matter. We improve the classical Langevin approach such that, apart from quasi-elastic scatterings between heavy quarks and the medium background, radiative energy loss is incorporated as well by treating gluon radiation as a recoil force term. The following hadronization of emitted heavy quarks is simulated via a hybrid fragmentation plus recombination model. And the diffusion of produced heavy mesons in the hadronic phase is described using the ultra-relativistic quantum molecular dynamics (UrQMD) model. Our calculation shows that while collisional energy loss dominates heavy quark motion inside QGP at low transverse momentum (pT) regime, contribution from gluon radiation is found significant at high pT. The recombination mechanism is important for heavy flavor meson production at intermediate energies. And the hadronic interactions in the end further enhances the suppression and the collective flow of heavy meson we observe. Within our newly developed framework, we present numerical results for the nuclear modification and elliptic flow of D mesons that are consistent with measurements at both RHIC and LHC experiments.
In addition, a new set of observables – heavy-flavor-tagged angular correlation functions – are explored and found to be potential candidates for distinguishing different energy loss mechanisms of heavy quarks inside a QGP medium.