Speaker
Description
We discuss two topics in hydrodynamic description of QGP fluids in high-energy nuclear collisions. We first constrain the initial conditions in the Bjorken expansion model by considering causality. When the system is far away from local equilibrium, the relativistic hydrodynamic equations tend to violate the causality. Within the conformal fluids in one-dimensionally expanding system, we find initial conditions are largely constrained due to causality conditions. This sheds a light on importance of core-corona initialization in high-energy nuclear collisions. We next discuss thermal fluctuations during hydrodynamic evolution (a.k.a. hydrodynamic fluctuations) in the Bjorken expansion model. We take account of the second order terms, which are required from causality, in linear perturbation of Bjorken's equations and analyze correlation functions of energy density in the longitudinal direction. We find a typical behavior of correlation functions which reflect transport properties of the QGP. We also argue generalized constitutive equations from a viewpoint of hydrodynamic fluctuations.
