Decaying scalar dark matter in the minimal left-right symmetric model

TL;DR

This paper proposes a new decaying scalar dark matter candidate within the minimal left-right symmetric model, linking dark matter stability with neutrino mass generation and leptogenesis, offering an economical explanation for multiple cosmological phenomena.

Contribution

It introduces a scalar dark matter candidate in the minimal left-right model, connecting its stability to neutrino masses and leptogenesis, expanding the model's explanatory power.

Findings

Scalar dark matter can be sufficiently stable cosmologically.

Constraints on right-handed neutrino mass affect neutrino mass and leptogenesis.

The scenario is economical but requires fine-tuning.

Abstract

In the minimal left-right symmetric theory, the dark matter candidate is usually ascribed to the lightest right-handed neutrino. Here we present an alternative decaying dark matter candidate in this model in terms of the lightest neutral scalar from the $SU(2)_R$-triplet field. This setup requires a vast hierarchy between the scalar mass and the left-right symmetry breaking scale, which renders the scalar dark matter sufficiently stable on cosmological time scales. The stability of the dark matter imposes constraints on the right-handed neutrino mass, which has consequences for the neutrino mass generation, as well as for leptogenesis. Although somewhat fine-tuned, it provides a very economical scenario wherein the minimal left-right model can simultaneously explain dark matter, neutrino masses, and the matter-antimatter asymmetry of the Universe.