Effective temperatures in out of equilibrium systems

Leticia F. Cugliandolo, Universite Pierre et Marie Curie - Paris 6, France

Thermodynamics is a powerful tool to understand and quantify the behaviour of equilibrium systems. Unfortunately, this theory cannot be applied to generic out of equilibrium cases and thermodynamic concepts such as temperature cannot be even defined in such situations. In the context of glassy systems effective temperatures have been defined from fluctuation-dissipation relations and their thermodynamic properties have been investigated in many different ways. In this talk I will review this notion as well as the experimental and numerical evidence for the existence of effective temperatures. In the end I will discuss two recent uses of the effective temperature ideas in, and their consequences for, two problems of great interest: active matter and quantum quench.