Light mass window of lepton portal dark matter

TL;DR

This paper proposes a lepton portal dark matter model with a light mass below 1GeV, highlighting its thermal production via neutrino annihilation and identifying neutrino telescopes as key for testing.

Contribution

It introduces a viable light mass window for lepton portal dark matter and discusses how to achieve the correct relic abundance while evading collider constraints.

Findings

Dark matter mass range of 10MeV-10GeV is largely unconstrained.

Neutrino telescopes are effective for detecting signals from dark matter annihilation.

Light scalar spectrum can be realized by adjusting scalar potential couplings.

Abstract

We explore a novel possibility that dark matter has a light mass below 1GeV in a lepton portal dark matter model. There are Yukawa couplings involving dark matter, left-handed leptons and an extra scalar doublet in the model. In the light mass region, dark matter is thermally produced via its annihilation into neutrinos. In order to obtain the correct relic abundance and avoid collider bounds, a neutral scalar is required to be light while charged scalars need to be heavier than the electroweak scale. Such a mass spectrum is realized by adjusting quartic couplings in the scalar potential or introducing an extra singlet scalar. It turns out that the mass region of 10MeV-10GeV is almost free from experimental and observational constraints. We also point out that searches for extra neutrino flux from galactic dark matter annihilations with neutrino telescopes are the best way to test our model.