Electric Dipole Moments as indirect probes of Dark Sectors

TL;DR

This paper explores how electric dipole moment measurements can indirectly detect dark sector interactions involving non-Abelian gauge groups, providing new avenues for probing dark matter models beyond current collider and dark photon searches.

Contribution

It introduces a novel phenomenological analysis of dimension five dark sector portals with CP violation, highlighting their potential to be tested through electron dipole moment experiments.

Findings

Dark photon search bounds can be complemented by EDM experiments for 1-100 GeV dark bosons.

Observable electron dipole moments are possible in models with SU(2)_D breaking to U(1)_D or nothing.

Parameter regions consistent with dark matter and experimental constraints can produce detectable EDM signals.

Abstract

Dark sectors provide beyond Standard Model scenarios which can address unresolved puzzles, such as the observed dark matter abundance or the baryon asymmetry of the Universe. A naturally small portal to the dark sector is obtained if dark-sector interactions stem from a non-Abelian hidden gauge group that couples through kinetic mixing with the hypercharge boson. In this work, we investigate the phenomenology of such a portal of dimension five in the presence of CP violation, focusing on its signatures in fermion electric dipole moments. We show that, currently unbounded regions of the parameter space from dark photon searches can be indirectly probed with upcoming electron dipole moment experiments for dark boson masses in the range $1-100$ GeV. We also discuss two particular scenarios where a $SU(2)_D$ dark gauge group spontaneously breaks into either an Abelian $U(1)_D$ or nothing. In both cases, we show that potentially observable electron dipole moments can be produced in vast regions of the parameter space compatible with current experimental constraints and observed dark matter abundance.