Two-component dark matter

Subhadittya Bhattacharya,Bohdan Grzadkowski,Aleksandra Drozd,Jose Wudka

doi:10.1007/jhep10(2013)158

Subhadittya Bhattacharya, Bohdan Grzadkowski + Show 2 more

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https://doi.org/10.1007/jhep10(2013)158

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Abstract

Abstract We study an extension of the Standard Model (SM) with two interacting cold Dark Matter (DM) candidates: a neutral Majorana fermion (ν) and a neutral scalar singlet (φ). The scalar φ interacts with the SM through the “Higgs portal” coupling while ν at the tree level interacts only with φ through Yukawa interactions. The relic abundance of ν and φ is found by solving the Boltzmann equations numerically; for the case m ν > m φ we also derive a reliable approximate analytical solution. Effects of the interaction between the two DM components are discussed. A scan over the parameter space is performed to determine the regions consistent with the WMAP data for DM relic abundance, and with the XENON100 direct detection limits for the DM-nucleus cross section. We find that although a large region of the parameter space is allowed by the WMAP constraints, the XENON100 data severely restricts the parameter space. Taking into account only amplitudes generated at the tree level one finds three allowed regions for the scalar mass: m φ ~ 62.5 GeV (corresponding to the vicinity of the Higgs boson resonance responsible for φφ annihilation into SM particles), m φ ≃ 130 − 140 GeV and m φ ≳ 3 TeV. 1-loop induced ν-nucleon scattering has been also calculated and discussed. A possibility of DM direct detection by the CREST-II experiment was considered.

Highlights

Where the ΩDM = ρDM /ρcrit is the ratio of the Dark Matter (DM) density over the critical density that corresponds to flat universe, and h is the Hubble constant in units of 100 km/(s.Mpc) [8]
We study an extension of the Standard Model (SM) with two interacting cold Dark Matter (DM) candidates: a neutral Majorana fermion (ν) and a neutral scalar singlet (φ)
It turns out that light green circles correspond to points for which the cross section is dominated by scalars, so again those points might be compared with single-component DM limits

Summary

Introduction

The fermionic and scalars DM components do interact, so the model provides a simple ‘laboratory’ where the interesting issue of interactions between DM components can be studied. Our model contains three new particles, all SM singlets: a real scalar φ, and two majorana fermions νh and ν (two fermions are required in order to generate non-trivial interactions between the DM components), only one of the fermions will contribute to the DM relic density. Though the DM sector can contain particles of any spin, the simplest possibilities correspond to the presence of fermions and scalars

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