X-ray photons from late-decaying majoron dark matter

TL;DR

This paper explores the potential of a massive majoron as late-decaying dark matter, analyzing its decay signatures, especially photon emissions, and comparing predictions with observations to constrain model parameters.

Contribution

It introduces a model-independent framework for constraining majoron dark matter decay via photon emissions and illustrates these constraints within a specific seesaw model.

Findings

Photon emission rates constrain majoron decay parameters.

Majoron can serve as late-decaying dark matter with detectable photon lines.

Model-specific predictions show potential for experimental tests.

Abstract

An attractive way to generate neutrino masses as required to account for current neutrino oscillation data involves the spontaneous breaking of lepton number. The resulting majoron may pick up a mass due to gravity. If its mass lies in the kilovolt scale, the majoron can play the role of late-decaying Dark Matter (LDDM), decaying mainly to neutrinos. In general the majoron has also a sub-dominant decay to two photons leading to a mono-energetic emission line which can be used as a test of the LDDM scenario. We compare expected photon emission rates with observations in order to obtain model independent restrictions on the relevant parameters. We also illustrate the resulting sensitivities within an explicit seesaw realisation, where the majoron couples to photons due to the presence of a Higgs triplet.