Massimiliano Semeraro — CY Cergy Paris Université #
Phase Separation Kinetics in a Polar Active Field Model #
Phase separation underlies a broad range of phenomena, from materials science to biological organization, and is commonly characterized by the emergence of universal power laws t^z governing domain-growth evolution. In the present contribution, we present our recent results concerning the investigation of a phase-separating polar active model comprising a scalar density field with an advective coupling to a polarization field, the latter modeling self-propulsion. Our analysis reveals a novel growth regime with exponent z∼0.6, significantly faster than the typical z∼1/3 behavior of conserved systems, and in quantitative agreement with the accelerated growth recently observed in extensive simulations of polar active particles. Combining numerical simulations in two and three dimensions with analytical arguments, we identify the mechanism underlying this accelerated coarsening: self-propulsion facilitates the creation of topological defects and compresses dense domains, thus leading to faster growth. We further demonstrate that the accelerated-growth regime is robust against several model extensions, including additional self-advection of the polarization field and non-equilibrium contributions inspired by well-established field-theoretic models. Overall, our results provide a minimal field-theoretical framework that explains recent observations of polar active particles, opening new perspectives for understanding living systems and designing active materials.