Asymmetric dark matter from semi-annihilation: unitarity constraints and long-lived final states

TL;DR

This paper introduces an asymmetric dark matter model involving semi-annihilation into long-lived particles, emphasizing the importance of unitarity and CPT constraints, and corrects previous inconsistencies in the literature.

Contribution

It provides a systematic approach to incorporate unitarity and CPT constraints in asymmetric dark matter models with semi-annihilation, addressing prior inconsistencies.

Findings

Identifies a critical inconsistency in previous models

Develops a consistent framework respecting unitarity and CPT

Clarifies the role of long-lived particles in dark matter relic density

Abstract

This work presents an asymmetric dark matter model with relic density determined by the freeze-out of asymmetric semi-annihilations into long-lived particles slowly decaying into the Standard Model states. We carefully consider the $CPT$ symmetry and unitarity constraints to the asymmetries entering the Boltzmann equation. The main idea of the paper is to point out a critical inconsistency in the previous literature, where these constraints are violated. We present a systematic approach to avoid the inconsistency.