Model-independent bound on the dark matter lifetime

Sergio Palomares-Ruiz

doi:10.1016/j.physletb.2008.05.040

Abstract

If dark matter (DM) is unstable, in order to be present today, its lifetime needs to be longer than the age of the Universe, tU≃4×1017 s. It is usually assumed that if DM decays it would do it with some strength through a radiative mode. In this case, very constraining limits can be obtained from observations of the diffuse gamma ray background. However, although reasonable, this is a model-dependent assumption. Here our only assumption is that DM decays into, at least, one Standard Model (SM) particle. Among these, neutrinos are the least detectable ones. Hence, if we assume that the only SM decay daughters are neutrinos, a limit on their flux from DM decays in the Milky Way sets a conservative, but stringent and model-independent bound on its lifetime.

Highlights

It is more than seventy years since an unknown missing mass was first postulated in order to understand the motion of galaxies in clusters [1]
In this letter we have obtained a general bound on the dark matter (DM) lifetime, which is several orders of magnitude more stringent than previous limits [6, 7]
In order to do so, we have considered that the only Standard Model (SM) products from DM decays are neutrinos, which are the least detectable particles of the SM

Summary

Introduction

It is more than seventy years since an unknown missing mass was first postulated in order to understand the motion of galaxies in clusters [1]. If we assume that the only SM products from the DM decay are neutrinos, a limit on their flux, conservatively and in a model-independent way, sets a lower bound on the DM lifetime.

Results

Conclusion