Neutron Portal and Dark Matter-Baryon Coincidence: from UV Completion to Phenomenology

TL;DR

This paper proposes a dynamical solution to the dark matter-baryon coincidence problem using the neutron portal, linking UV physics to phenomenology and gravitational wave signals.

Contribution

It introduces a framework connecting dark matter asymmetry with neutron portal UV completion, explaining the GeV-scale dark matter mass and related phenomenology.

Findings

Dark confinement scale naturally arises at GeV from UV completion.

The neutron portal scale is linked to the confinement scale through UV dynamics.

Cosmological constraints and experimental prospects are discussed.

Abstract

We present a dynamical solution to the dark matter-baryon coincidence problem based on the neutron portal operator connecting the visible and dark sector asymmetries. This framework is motivated by the possibility that a strongly supercooled dark confinement phase transition accounts for the nano-Hz stochastic gravitational wave signal observed by pulsar timing arrays, while also generating the dark matter and baryon asymmetry in the Universe. We show that the GeV-scale mass of asymmetric dark matter can be naturally correlated with the (multi-)TeV scale cut-off for the neutron portal through its ultraviolet completion. The dark sector is governed by an approximate fixed point and confines once the heavy portal states are integrated out, dynamically generating a scale of $\mathcal{O} ({\rm GeV})$. We analyze both tree and loop-level ultraviolet completions and demonstrate how the resulting confinement scale is linked to the effective neutron portal scale. We also discuss cosmological constraints and experimental prospects in beam dump searches and colliders for probing the neutron portal.