Remote Nordic HET seminar: Akash Jain

Speaker: Akash Jain

Title: Non-universality of hydrodynamics

Abstract: The late-time long-distance behaviour of a many-body system is usually described by the framework of hydrodynamics or similar condensed matter models based on the (possibly spontaneously broken) symmetries that the system enjoys. These models are characterised by a set of transport coefficients, such as viscosities and conductivity, that capture the transport properties of conserved charges over macroscopic scales. In this talk, we will investigate a new kind of transport coefficients that are not present in the usual formulation of hydrodynamics, but nonetheless affect the late time dynamics of conserved charges. Physically, these new coefficients arise due to the interaction of the hydrodynamic degrees of freedom with the background bath of thermal noise present out of equilibrium. For the purposes of this investigation, I will spend some time to review the newly developed Schwinger-Keldysh effective action formulation of non-equilibrium field theories, which allows one to systematically keep track of thermal noise and their correlations. The talk will be based on the recent preprint https://arxiv.org/abs/2009.01356.