Orateur
Description
Hydrodynamics provides a universal low-energy effective description of interacting many-body systems. The Schwinger–Keldysh effective field theory (SK EFT) offers a Wilsonian, action-based formulation of hydrodynamics that systematically incorporates fluctuations. In this approach, the effective action is generically complex, encoding macroscopic dissipation. The framework features a discrete KMS symmetry which is responsible for implementing fluctuation-dissipation relations and underlies the emergence of the second law of thermodynamics. In this talk, we will discuss the first-ever derivation of an SK EFT directly from a local, unitary microscopic Hamiltonian. Specifically, we will consider a one-dimensional chain of SYK dots with Gaussian-random interactions between nearest neighbours. Its low-energy dynamics is governed by an SK EFT for energy diffusion. We will identify the fundamental and emergent symmetries of this theory and derive the associated classical entropy current for SYK chains. Time permitting, we will also comment on applications to out-of-time-ordered correlators of energy fluctuations. The talk will be based on the recent paper: https://arxiv.org/pdf/2604.18675.
