Seminar in Hadronic Physics

Thermal hydrodynamical fluctuations and observables in heavy ion collisions

Clint Young

University of Minnesota

The statistics of thermal fluctuations in a static fluid contains information about the fluid's equation of state. Meanwhile, the fluctuations of an expanding, cooling fluid are driven away from thermal expectation values and have variances and autocorrelations across space which are determined by the fluid's transport coefficients. Both heavy ion collisions and the early universe can be described as viscous, expanding fluids. The perturbations in Israel-Stewart hydrodynamics have been linearized and described as a stochastic process, whose approach and deviations from thermal expectation values can be quantified. This source for event-by-event fluctuations in heavy ion collisions has the strength of being described without any additional free parameters, but is sub-dominant and will not explain all observables. Its importance lies mainly with its potential usage as an independent probe of shear viscosity of hot nuclear matter.