Entropy Production in Field Theories without Time-Reversal Symmetry: Quantifying the Non-Equilibrium Character of Active Matter

摘要: Active-matter systems operate far from equilibrium because of the continuous energy injection at scale constituent particles. At larger scales, described by coarse-grained models, global entropy production rate $S$ quantifies probability ratio forward and reversed dynamics hence importance irreversibility such scales: It vanishes whenever active system reduces to that an effective model. We evaluate for a class scalar stochastic field theories describing density self-propelled particles without alignment interactions, capturing key phenomena as motility-induced phase separation. show how can be decomposed locally (in real space) or spectrally Fourier space), allowing detailed examination spatial structure correlations underly departures equilibrium. For phase-separated systems, local is concentrated mainly on interfaces, with bulk contribution tends zero in weak-noise limit. In homogeneous states, we find generalized Harada-Sasa relation directly expresses terms wave-vector-dependent deviation fluctuation-dissipation between response functions correlators. discuss extensions case where particle coupled momentum-conserving solvent situations current, rather than density, should chosen dynamical field. expect new conceptual tools developed here broadly useful context matter, one distinguish when activity plays essential role dynamics.