Monochromatic neutrinos from dark matter through the Higgs portal

TL;DR

This paper proposes a minimal dark matter model with a fermion singlet interacting via the Higgs portal, predicting a monochromatic neutrino signal from the Sun that could be detectable by neutrino telescopes.

Contribution

The model introduces a new annihilation channel involving a heavy Dirac neutrino, aligning relic abundance with experimental bounds and predicting observable neutrino signals.

Findings

Predicted neutrino signals could be above the solar neutrino background.

Model remains consistent with direct detection constraints.

Potential for detection at neutrino telescopes and colliders.

Abstract

We define a minimal model of dark matter with a fermion singlet $\chi$ coupled to the visible sector through the Higgs portal and with a heavy Dirac neutrino $N$ that opens the annihilation channel $\chi \chi \to N \nu$. The model provides the observed relic abundance consistently with bounds from direct searches and implies a monochromatic neutrino signal at 10 GeV-1 TeV in indirect searches. In particular, we obtain the capture rate of $\chi$ by the Sun and show that the signal could be above the "neutrino floor" produced by cosmic rays showering in the solar surface. In most benchmark models this solar astrophysical background is above the expected dark matter signal, so the model that we propose is a canonical example of WIMP not excluded by direct searches that could be studied at neutrino telescopes and also at colliders.