Seminars on Nov. 19th
B105
CHEP
Hydrodynamics and thermalization in heavy-ion collisions
Lipei Du(Ohio State University)
Abstract: Dissipative relativistic fluid dynamics has been unexpectedly successful in describing the evolution of the hot and dense fireballs created in relativistic light- and heavy-ion collisions at very high collision energies, and the distributions of particles emitted from them. I will discuss several recent developments that extend the applicability of the approach to lower collision energies: (1) a dynamical initialization model that takes into account the finite duration of the interpenetration time of the two colliding nuclei during which energy is deposited into the evolving fireball; (2) the consistent evolution of the net baryon density and of the dissipative baryon diffusion current which are both non-zero and possibly large at lower collision energies; and (3) the non-hydrodynamic evolution of critical slow modes coupled to the hydrodynamic evolution of the medium as it passes by the critical point in the QCD phase diagram at large net baryon density, using the newly developed HYDRO+ framework. By monitoring the size of the dissipative flows (including critical slow modes) as the system evolves hydrodynamically we follow the approach of the system towards local thermodynamic equilibrium. In addition, some recent insights into the process of hydrodynamization via the rapid approach towards a non-equilibrium-hydrodynamic attractor during the very early far-from-equilibrium stage of the dynamical evolution will be reported. These shed new light on the origin of the remarkable success of hydrodynamics even in far-from-equilibrium situations.
Hydrodynamics and Equation of State Near the QCD Critical Point
Xin An(University of Illinois at Chicago)
Abstract: The existence and location of the hypothetical critical point, as a landmark of the QCD phase diagram, remains to be an unsolved fundamental question. In order to search for this critical point, the ongoing Beam Energy Scan program is conducted at the Relativistic Heavy Ion Collider (RHIC). The dynamical evolution of strongly interacting matter created in RHIC is well described by hydrodynamics, yet a framework incorporating fluctuations and critical slowing down needs to be developed and compared to experimental measurements quantitatively. In this talk, I will present a general systematic formalism describing dynamics of hydrodynamic fluctuations in an arbitrary relativistic flow and show how this general formalism is applied to the region near the QCD critical point. I will also discuss the critical equation of state, which is necessary to close the system of cutoff-independent hydrodynamic equations we obtained.
