Speaker
Description
Relativistic hydrodynamics has proven highly successful in describing the evolution of quark-gluon plasma in heavy-ion collisions. To account for event-by-event fluctuations in observables, especially those sensitive to the critical point, a framework of relativistic fluctuating hydrodynamics is required. We establish such a framework by introducing correlation functions for fluctuating hydrodynamic fields and deriving deterministic equations for their evolution from hydrodynamics. The most nontrivial part of this approach is the description of local velocity fluctuations. We introduce a novel approach to this problem. Fluctuations are represented in a local triad basis orthogonal to local average 4-velocity. The resulting equations possess local gauge invariance corresponding to arbitrary SO(3) rotations of this triad basis. The gauge invariance together with the usual properties, such as fluctuation-dissipation relations or KMS symmetry, nontrivially constrain the form of the equations. These results provide the essential and complete building blocks for a general theory of stochastic hydrodynamics with non-Gaussian fluctuations, forming an integral part of the theoretical framework for interpreting the RHIC Beam Energy Scan II results announced recently.
