Non-Gaussian hydrodynamic fluctuations in an expanding relativistic fluid
TLDR
This paper analyzes non-Gaussian hydrodynamic fluctuations in expanding relativistic fluids, deriving evolution equations and showing the importance of the average Landau frame.
Key contributions
- Derived analytical evolution equations for two- and three-point velocity correlators in Bjorken flow.
- Showed the average Landau frame is optimal for studying relativistic non-Gaussian velocity fluctuations.
- Demonstrated three-point correlators exhibit nonlinear dependence on two-point functions and memory effects.
Why it matters
This work provides crucial analytical tools for understanding non-Gaussian fluctuations in relativistic fluids, particularly relevant for heavy-ion collisions. Its findings on correlator dynamics and frame choice are vital for the experimental search for the QCD critical point.
Original Abstract
We consider non-equilibrium evolution of non-Gaussian fluctuations in a hydrodynamic system undergoing a boost-invariant expansion described by Bjorken flow. We derive the evolution equations for two- and three-point velocity correlators using the effective field theory framework and present analytical solutions for them. We show that the average Landau frame is better suited for studying non-Gaussian fluctuations of velocity when relativistic effects are important. In the Bjorken background, the average Landau frame corresponds to the density frame. We demonstrate that the three-point correlators depend nonlinearly on the non-equilibrium dynamics of the two-point functions, and exhibit non-trivial effects such as memory. The importance of these effects in the context of the search for the QCD critical point via fluctuations is discussed.
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