Speaker
Description
Recent developments in the Schwinger–Keldysh (SK) formalism have made it possible to formulate effective field theories (EFTs) for finite-temperature, out-of-equilibrium systems, including dissipative effects and fluctuations. However, a systematic and transparent derivation of SK EFT actions for fluid systems with a generic internal symmetry structure remains incomplete.
In this talk, I will present a coset-based construction of SK EFT Lagrangians at first dissipative order for generic fluid systems, without any specific assumption on the internal symmetry group. Focusing on charged fluids and superfluids as concrete examples, I will (re)derive thermo- and hydrodynamical phenomenological consequences. I will also show how the coset construction clarifies the interplay between physical symmetries, such as the dynamical KMS symmetry, and redundancies in the description, including fluid diffeomorphisms and chemical shift symmetries.
Finally, I will outline possible applications to the hydrodynamics of axion-sourced stellar remnants, where the SK EFT framework may provide a useful language for describing their finite-density, dissipative dynamics, possibly relevant to astrophysical bounds on the axion parameter space.