Multicomponent Dark Matter in Radiative Seesaw Models

TL;DR

This paper explores radiative seesaw models with an exact Z2×Z2' symmetry, predicting multiple stable neutral particles, and investigates their implications for dark matter, dark radiation, and related phenomenology.

Contribution

It introduces two specific models with multi-component dark matter and dark radiation, analyzing their unique features and phenomenological consequences.

Findings

Non-standard dark matter annihilation processes influence relic abundance.

Dark matter annihilation can produce monochromatic neutrino lines.

Yukawa coupling structures link cosmology, lepton flavor violation, and Higgs decays.

Abstract

We discuss radiative seesaw models, in which an exact $Z_2\times Z_2'$ symmetry is imposed. Due to the exact $Z_2\times Z_2'$ symmetry, neutrino masses are generated at a two-loop level and at least two extra stable electrically neutral particles are predicted. We consider two models: one has a multi-component dark matter system and the other one has a dark radiation in addition to a dark matter. In the multi-component dark matter system, non-standard dark matter annihilation processes exist. We find that they play important roles in determining the relic abundance and also responsible for the monochromatic neutrino lines resulting from the dark matter annihilation process. In the model with the dark radiation, the structure of the Yukawa coupling is considerably constrained and gives an interesting relationship among cosmology, lepton flavor violating decay of the charged leptons and the decay of the inert Higgs bosons.