Microphase separation in active filament systems maintained by cyclic dynamics of cluster size and order

The onset of polar flocking in active matter is discontinuous, akin to gas-liquid phase transitions, except that the steady state exhibits microphase separation into clusters. While these features have been observed theoretical models and experiments, little known about underlying mesoscopic processes at cluster level. Here we show emergence maintenance order are governed by interplay between assembly disassembly dynamics clusters with varying size degree order. Using agent-based simulations propelled filaments a parameter regime relevant for actomyosin motility assays, monitor temporal evolution statistics transport We find that, over broad range, determined nucleation growth clusters, where threshold depends not only on but also its moment. Growth involves self-replication, established fragmentation. Maintenance microphase-separated, polar-ordered results from cyclic order, driven an nucleation, coagulation, fragmentation evaporation single filaments. These findings corroborated kinetic model includes elementary cluster-level processes. It consistently reproduces as well turnover disordered ordered back. Such could represent general mechanism systems.