Can A Higgs Portal Dark Matter be Compatible with the Anti-proton Cosmic-ray?

TL;DR

This paper explores whether light Higgs portal dark matter models can reconcile direct detection signals with the lack of anti-proton excess in cosmic rays, favoring Dirac over scalar dark matter due to annihilation properties.

Contribution

It demonstrates that a Dirac Higgs portal dark matter model can satisfy relic density, direct detection, and collider constraints while remaining consistent with cosmic-ray anti-proton observations.

Findings

Dirac dark matter is preferred over scalar due to annihilation characteristics.

A parameter space exists where relic density, direct detection signals, and collider constraints are all satisfied.

The model can explain CoGeNT signals without producing excess anti-protons in cosmic rays.

Abstract

Recent direct detection experiments of Dark Matter (DM), CoGeNT and DAMA implicate a light DM of a few GeV. Such a light DM would generate a large amount of anti-proton since suppression for anti-proton flux from DM annihilation is ineffective. We discuss whether a light dark matter with mass of 5-15 GeV, which is especially in favor of the recent experiments reported by CoGeNT, is compatible with the anti-proton no excess in the cosmic-ray. In view of the direct detection of DM and no anti-proton excess in the cosmic-ray both, we show that a Dirac DM is favored than a scalar one since there is no s-wave of the annihilation cross section for the Dirac DM. A large elastic cross section for direct detection can be obtained through the additional light Higgs exchange. We show an allowed region that simultaneously satisfies the DM relic density, the elastic cross section favored by CoGeNT and also the constraint of H_L Z Z coupling of the light Higgs boson by LEP.