Date : November 1, 2022, 16:00 CET
Alexandre Serantes (University of Barcelona)
Link: https://zoom.us/j/98260147834?pwd=VW5BQStqUGUrUFFzWG1jL2tuWXJoZz09
Relativistic hydrodynamics: a singulant perspective
Abstract: The formulation of relativistic hydrodynamics in an effective field theory language rests on a gradient expansion around local thermal equilibrium. Until recently, our understanding of the large-order behavior of this gradient expansion was restricted to two limiting scenarios: generic fluid flows in the linear response regime and nonlinear comoving flows highly constrained by symmetries. In this talk, I will first provide new evidence demonstrating that, at the nonlinear level, the gradient expansion is a factorially divergent series beyond comoving flows. Then, I will discuss how singulants offer a new perspective to understand the asymptotic behavior of the gradient expansion in general situations. Singulants emerge from a dramatic reorganization of the gradient expansion at large orders. I will show that they obey simple equations of motion dictated by linear response around the local state of the fluid, and I will provide explicit examples where they rule the optimal truncation of the gradient expansion.
