Violation of the fluctuation–dissipation theorem in glassy systems: basic notions and the numerical evidence

Abstract

This review reports on the research done during the past years on violations\nof the fluctuation-dissipation theorem (FDT) in glassy systems. It is focused\non the existence of a quasi-fluctuation-dissipation theorem (QFDT) in glassy\nsystems and the currently supporting knowledge gained from numerical simulation\nstudies. It covers a broad range of non-stationary aging and stationary driven\nsystems such as structural-glasses, spin-glasses, coarsening systems,\nferromagnetic models at criticality, trap models, models with entropy barriers,\nkinetically constrained models, sheared systems and granular media. The review\nis divided into four main parts: 1) An introductory section explaining basic\nnotions related to the existence of the FDT in equilibrium and its possible\nextension to the glassy regime (QFDT), 2) A description of the basic analytical\ntools and results derived in the framework of some exactly solvable models, 3)\nA detailed report of the current evidence in favour of the QFDT and 4) A brief\ndigression on the experimental evidence in its favour. This review is intended\nfor inexpert readers who want to learn about the basic notions and concepts\nrelated to the existence of the QFDT as well as for the more expert readers who\nmay be interested in more specific results.\n