Exploring Direct Detection Suppressed Regions in a Simple 2-Scalar Mediator Model of Scalar Dark Matter

TL;DR

This paper investigates parameter regions in a simple scalar dark matter model where direct detection signals are suppressed, especially due to interference effects at higher dark matter masses, revealing viable unexplored areas.

Contribution

It introduces the analysis of interference effects between annihilation channels in a scalar dark matter model, expanding understanding of suppressed direct detection regions.

Findings

Significant parameter space remains unconstrained by current direct detection limits.

Interference effects at higher DM masses lead to smaller detection cross sections.

New annihilation channels influence relic abundance and detection prospects.

Abstract

We explore regions of parameter space that give rise to suppressed direct detection cross sections in a simple model of scalar dark matter with a scalar portal that mixes with the standard model Higgs. We found that even this simple model allows considerable room in the parameter space that has not been excluded by direct detection limits. A number of effects leading to this result have been previously noted. Our main new result explores interference effects between different contributions to DM annihilation when the DM mass is larger than the scalar portal mass. New annihilation channels open up and the parameters of the model need to compensate to give the correct DM relic abundance, resulting in smaller direct detection cross sections. We find that even in a very simple model of DM there are still sizeable regions of parameter space that are not ruled out by experiment.