Stable Bound States of Asymmetric Dark Matter

TL;DR

This paper investigates the formation and properties of stable bound states of asymmetric dark matter within a simple effective field theory, exploring their implications for early universe formation and detection.

Contribution

It introduces a model with a Dirac fermion dark matter and a scalar mediator, analyzing the conditions for stable bound states and their potential observability.

Findings

Stable dark matter bound states can form for certain parameters.

Large bound states ('nuggets') composed of many dark matter particles are possible.

Results are applicable to both asymmetric and symmetric dark matter scenarios.

Abstract

The simplest renormalizable effective field theories with asymmetric dark matter bound states contain two additional gauge singlet fields one being the dark matter and the other a mediator particle that the dark matter annihilates into. We examine the physics of one such model with a Dirac fermion as the dark matter and a real scalar mediator. For a range of parameters the Yukawa coupling of the dark matter to the mediator gives rise to stable asymmetric dark matter bound states. We derive properties of the bound states including nuggets formed from $N\gg1$ dark matter particles. We also consider the formation of bound states in the early universe and direct detection of dark matter bound states. Many of our results also hold for symmetric dark matter.