Fluctuation-Dissipation Relations in the absence of Detailed Balance: formalism and applications to Active Matter

Dal Cengio, SaraLevis, DemianPagonabarraga Mora, Ignacio2022-04-052022-04-052021-01-071742-5468https://hdl.handle.net/2445/184759We present a comprehensive study about the relationship between the way Detailed Balance is broken in non-equilibrium systems and the resulting violations of the Fluctuation-Dissipation Theorem. Starting from stochastic dynamics with both odd and even variables under Time-Reversal, we exploit the relation between entropy production and the breakdown of Detailed Balance to establish general constraints on the non-equilibrium steady-states (NESS), which relate the non-equilibrium character of the dynamics with symmetry properties of the NESS distribution. This provides a direct route to derive extended Fluctuation-Dissipation Relations, expressing the linear response function in terms of NESS correlations. Such framework provides a unified way to understand the departure from equilibrium of active systems and its linear response. We then consider two paradigmatic models of interacting self-propelled particles, namely Active Brownian Particles (ABP) and Active Ornstein-Uhlenbeck Particles (AOUP). We analyze the non-equilibrium character of these systems (also within a Markov and a Chapman-Enskog approximation) and derive extended Fluctuation-Dissipation Relations for them, clarifying which features of these active model systems are genuinely non-equilibrium.application/pdfeng(c) IOP Publishing Ltd and SISSA Medialab srl, 2021Fluctuacions (Física)Matèria condensada tovaMecànica estadísticaFluctuations (Physics)Soft condensed matterStatistical mechanicsFluctuation-Dissipation Relations in the absence of Detailed Balance: formalism and applications to Active Matterinfo:eu-repo/semantics/article7197512022-04-05info:eu-repo/semantics/openAccess