Dark Photon Dark Matter without Stueckelberg Mass

TL;DR

This paper explores dark photon dark matter where the mass arises from the Higgs mechanism, leading to complex dynamics and significantly different predictions from Stueckelberg models, with implications for cosmology and constraints from isocurvature perturbations.

Contribution

It introduces a Higgs mechanism-based model for dark photon dark matter, analyzing its unique dynamics and contrasting it with Stueckelberg theories, highlighting the dependence on curvature couplings and inflation scale.

Findings

Dark sector exhibits thermalization, phase transitions, and cosmic string production.

Phenomenology differs greatly from Stueckelberg models except in extreme parameter regions.

Strong constraints from isocurvature perturbations unless the dark sector is Weyl invariant.

Abstract

We study the scenario of dark photon Dark Matter where the mass is generated through the Higgs mechanism rather than the constant Stueckelberg mass. In this construction the dark sector contains necessarily extra degrees of freedom and interactions that lead to non-trivial dynamics including thermalization, phase transitions, cosmic string production. As a consequence the predictions of Stueckelberg theories are vastly modified, strongly depending on the couplings to curvature and on the scale of inflation $H_I$ compared to the scale $f$ of spontaneous symmetry breaking. We find in particular that only in extreme regions of parameter space the phenomenology of Stueckelberg dark photon is reproduced. These scenarios are strongly constrained by isocurvature perturbations unless the dark sector is approximately Weyl invariant.