Neutrino Portal via Loops

TL;DR

This paper explores a novel neutrino portal scenario where dark matter predominantly annihilates through loop processes, affecting relic density calculations and neutrino properties in dense dark matter environments.

Contribution

It introduces a new mechanism where dark matter freeze-out is driven mainly by loop-induced processes in the neutrino portal, with detailed calculations of related neutrino properties.

Findings

Dark matter relic density can be achieved via loop processes involving neutrinos.

Neutrino Debye mass and oscillation probabilities are computed in dark halos.

Impacts on Earth-based neutrino observations are negligible.

Abstract

One loop correction to the dark matter (DM) annihilation cross section is usually assumed to be sub-dominate in calculating the DM relic density. In this paper, we propose a scenario where DM freezes out mainly via loops in the neutrino portal. For a scalar DM annihilating into neutrino via a triangle diagram, or a Majorana DM annihilating into neutrino via a box diagram, the observed DM relic density can be generated if the mediator is Majorana fermion. We further work out the neutrino Debye mass and neutrino oscillation probabilities in the dark halo. Numerical results show that impactions of DM to these physical observables are negligible on the Earth, however the analytical results can be applied to evaluate neutrino properties in a dense DM environment.