Millicharge or Decay: A Critical Take on Minimal Dark Matter

TL;DR

This paper critically examines Minimal Dark Matter models, proposing millicharged candidates and decays to address limitations, and explores their phenomenological implications.

Contribution

It introduces two novel directions for MDM: millicharged stable candidates and models with lowered cutoff allowing decay, expanding the framework's viability.

Findings

Identified new viable MDM candidates with millicharge.

Analyzed phenomenology of decaying MDM models.

Proposed generalizations to the original MDM paradigm.

Abstract

Minimal Dark Matter (MDM) is a theoretical framework highly appreciated for its minimality and yet its predictivity. Of the two only viable candidates singled out in the original analysis, the scalar eptaplet has been found to decay too quickly to be around today, while the fermionic quintuplet is now being probed by indirect Dark Matter (DM) searches. It is therefore timely to critically review the MDM paradigm, possibly pointing out generalizations of this framework. We propose and explore two distinct directions. One is to abandon the assumption of DM electric neutrality in favor of absolutely stable, millicharged DM candidates which are part of $SU(2)_{\text{L}}$ multiplets with integer isospin. Another possibility is to lower the cutoff of the model, which was originally fixed at the Planck scale, to allow for DM decays. We find new viable MDM candidates and study their phenomenology in detail.