Leptogenesis and Dark Matter in an Inverse Seesaw from gauged B-L breaking

Abstract

We study a dynamical realization of the low-scale Inverse Seesaw mechanism in which the approximate $B-L$ symmetry is gauged and spontaneously broken. Anomaly cancellation requires additional chiral fermions, one of which becomes a stable dark matter candidate after symmetry breaking, while another remains massless and contributes to dark radiation. Focusing on the regime of feeble gauge interactions, we compute the dark matter relic abundance produced via the freeze-in mechanism through the $B-L$ gauge boson and identify the parameter space consistent with cosmological and laboratory constraints. We show that the same region naturally avoids thermalization of heavy neutral leptons, preserving the viability of ARS leptogenesis. The interplay between dark matter production, dark radiation constraints, and leptogenesis requirements leads to a predictive scenario where future cosmological surveys and intensity-frontier experiments such as SHiP can probe significant portions of the viable parameter space.