Principal profiles, characteristic communication and critical asymptotics for cooperative nonlocal systems on the circle

Abstract

We study cooperative nonlocal transport on a circle with species-dependent constant velocities and arbitrary $L^1$ probability kernels. For periodic coefficients, the period map is a compact perturbation of the no-jump map. We construct separate receiving and sending characteristic scans: under a two-tree condition based at one active component, a positive Floquet profile exists exactly when the full period map has strictly larger spectral radius than its no-jump part. The other jump rates may vanish. The scans provide an integral minorant and positive jump return; a separate coefficient inequality verifies the spectral gap. Smooth locking examples distinguish communication from frozen-time mixing, while a resonant example separates positive return from spectral separation. Autonomous nonzero velocities and union-graph connectivity yield a simple principal pair; one active component suffices for exponential mixing. We also prove local perturbation results. For quadratic self-regulation, the same principal projection gives a transverse response whose averaged cubic coefficient is a nonnegative asymptotic variance. It determines both the critical $t^{-2}\log t$ correction and the second-order period-averaged amplitude of the positive branch.