Spinning mixtures: nonreciprocity transfers chirality across scales in scalar densities

Abstract: We present a minimal model for mixtures of chiral active particles, formulated solely in terms of the number densities of the species. Nonreciprocity and chirality enter the chemical potential at vanishing order in spatial gradients, taking the form of local and non-local contributions. Chirality manifests as the curl of the nonreciprocal current, while the latter is simultaneously strongly modified by former. Their interplay generates distinctive dynamical states, including phase separation with edge currents and a spatiotemporally disordered phase with both chiral and nonreciprocal signatures.