Leptonic Dark Matter with Scalar Dilepton Mediator

TL;DR

This paper proposes a leptonic dark matter model with a scalar dilepton mediator that decays into neutrinos, addressing issues with light scalar mediators affecting the cosmic microwave background.

Contribution

It introduces a novel mechanism linking Dirac neutrinos and dark matter via a scalar dilepton mediator, ensuring compatibility with CMB constraints.

Findings

Mediator decays predominantly into neutrinos.

Model maintains consistency with cosmic microwave background observations.

Provides a simple framework for leptonic dark matter interactions.

Abstract

A simple and elegant mechanism is proposed to resolve the problem of having a light scalar mediator for self-interacting dark matter and the resulting disruption to the cosmic microwave background (CMB) at late times by the former's enhanced Sommerfeld production and decay. The crucial idea is to have Dirac neutrinos with the conservation of U(1) lepton number extended to the dark sector. The simplest scenario consists of scalar or fermion dark matter with unit lepton number accompanied by a light scalar dilepton mediator, which decays to two neutrinos.