Thermalization and hydrodynamics of two-dimensional quantum field theories

We consider 2d QFTs as relevant deformations of CFTs in the thermodynamic limit. Using causality and KPZ universality, we place a lower bound on timescale characterizing onset hydrodynamics. The is determined parametrically terms temperature scale associated with deformation. This typically much stronger than \frac{1}{T} 1T , expected quantum equilibration time. Subluminality sound further allows us to define C display="inline">C -function, constrain sign T\bar T display="inline">TT‾ term EFTs.