Decaying Majoron Dark Matter and Neutrino Masses

TL;DR

This paper reviews the majoron as a warm dark matter candidate, analyzing constraints from cosmic microwave background data, and explores its implications for neutrino mass models and cosmology.

Contribution

It provides updated constraints on majoron mass, lifetime, and abundance, linking dark matter properties with neutrino mass generation mechanisms.

Findings

Majoron mass constrained to 0.12-0.17 keV for thermal production

Majoron lifetime exceeds 250 Gyrs

Lepton number breaking scale above 10^6 GeV

Abstract

We review the recent proposal by Lattanzi & Valle of the majoron as a suitable warm dark matter candidate. The majoron is the Goldstone boson associated to the spontaneous breaking of ungauged lepton number, one of the mechanisms proposed to give rise to neutrino masses. The majoron can acquire a mass through quantum gravity effects, and can possibly account for the observed dark matter component of the Universe. We present constraints on the majoron lifetime, mass and abundance obtained by the analysis of the cosmic microwave background data. We find that, in the case of thermal production, the limits for the majoron mass read 0.12 keV<m_J<0.17 keV, and discuss how these limits are modified in the non-thermal case. The majoron lifetime is constrained to be larger than 250 Gyrs. We also apply this results to a given seesaw model for the generation of neutrino masses, and find that this constraints the energy scale for the lepton number breaking phase transition to be above 10^6 GeV. We thus find that the majoron decaying dark matter (DDM) scenario fits nicely in models where neutrino masses arise "a la seesaw" and may lead to other possible cosmological implications.