Coscattering in the Extended Singlet-Scalar Higgs Portal

TL;DR

This paper explores a Higgs portal model with two singlet scalars where dark matter relic abundance is set by coscattering, and examines collider prospects for the heavier scalar as a long-lived particle.

Contribution

It introduces a simple Higgs portal model with two singlet scalars demonstrating viable dark matter relic abundance via coscattering, and analyzes collider detection prospects.

Findings

Viable parameter space satisfying relic abundance and experimental bounds.

Heavier scalar can be long-lived, detectable at colliders.

Model evades direct detection and BBN constraints.

Abstract

We study the coscattering mechanism in a simple Higgs portal which add two real singlet scalars to the Standard Model. In this scenario, the lighter scalar is stabilized by a single $\mathcal{Z}_2$ symmetry and acts as the dark matter relic, whose freeze-out is driven by conversion processes. The heavier scalar becomes an unstable state which participate actively in the coscattering. We find viable parameter regions fulfilling the measured relic abundance, while evading direct detection and big-bang nucleosynthesis bounds. In addition, we discuss collider prospects for the heavier scalar as a long-lived particle at present and future detectors.