Lifetime Constraints for Late Dark Matter Decay

TL;DR

This paper investigates late-decaying dark matter models where the decay products are neutrinos or electron-positron pairs, deriving new constraints on their lifetimes and significantly narrowing the viable parameter space for these scenarios.

Contribution

It provides the first comprehensive limits on dark matter decay models with neutrino or electron-positron decay products, extending constraints beyond photon-producing decays.

Findings

Stringent limits on dark matter lifetime for neutrino and electron-positron decay channels.

Elimination of large parameter space for late decay models with Standard Model final states.

Constraints applicable across a wide range of dark matter masses.

Abstract

We consider a class of late-decaying dark-matter models, in which a dark matter particle decays to a heavy stable daughter of approximately the same mass, together with one or more relativistic particles which carry away only a small fraction of the parent rest mass. Such decays can affect galactic halo structure and evolution, and have been invoked as a remedy to some of the small scale structure-formation problems of cold dark matter. There are existing stringent limits on the dark matter lifetime if the decays produce photons. By considering examples in which the relativistic decay products instead consist of neutrinos or electron-position pairs, we derive stringent limits on these scenarios for a wide range of dark matter masses. We thus eliminate a sizable portion of the parameter space for these late decay models if the dominant decay channel involves Standard Model final states.