Thermal Dark Photon Dark Matter, Coscattering, and Long-lived ALPs

TL;DR

This paper investigates the thermal production of dark photon dark matter via a dark-axion portal, exploring different freeze-out regimes and the potential for long-lived axion-like particles detectable at colliders.

Contribution

It provides a detailed analysis of multiple thermal freeze-out regimes for dark photon dark matter within a dark-axion portal framework, including the viability of long-lived ALPs.

Findings

Viable dark matter scenarios in three freeze-out regimes.

Parameter space for GeV-TeV scale dark states identified.

Prospects for detecting long-lived ALPs at colliders discussed.

Abstract

We study the thermal freeze-out of a dark photon dark matter in the so-called dark-axion portal - a triple coupling among a dark photon, an axion-like particle and the SM $\gamma$ or $Z$ boson. We analyze in detail the thermal production regimes: coscattering (aka conversion driven freeze-out), mediator freeze-out, and coannihilations. We found viable DM scenarios fulfilling the correct relic abundance in the three regimes. Apart of analyzing the parameter space for dark state masses between the GeV-TeV scale, we explore the prospects of having the axion-like field as a long-lived particle, possibly to be observed at the LHC and future detectors.