Neutrinos from Inert Doublet Dark Matter

TL;DR

This work analyzes neutrino signatures from Inert Doublet Model dark matter annihilation in the Sun, Earth, and Galactic centre across three mass regimes: $m_{H_0}\in[3,8]$ GeV (low), $[40,80]$ GeV (middle), and $\gtrsim 500$ GeV (high). It computes capture, annihilation, and neutrino yields within a Higgs-portal IDM, using an NFW halo and standard astrophysical inputs to predict neutrino-induced muon fluxes for current detectors, and compares them with Super-Kamiokande, IceCube, and ANTARES sensitivities. The results show Sun constraints on the low-mass region, challenging prospects for Earth signals in the middle range (though enhancements from loop corrections or a Majorana-neutrino extension can boost mono-energetic neutrinos), and only marginal Galactic-centre signals for high-mass IDM unless substantial boost factors are present, consistent with gamma-ray constraints. The study highlights how indirect detection complements direct searches and explores model extensions that can significantly alter neutrino fluxes and detection prospects.

Abstract

We investigate the signatures of neutrinos produced in the annihilation of WIMP dark matter in the Earth, the Sun and at the Galactic centre within the framework of the Inert Doublet Model and extensions. We consider a dark matter candidate, that we take to be one of the neutral components of an extra Higgs doublet, in three distinct mass ranges, which have all been shown previously to be consistent with both WMAP abundance and direct detection experiments exclusion limits. Specifically, we consider a light WIMP with mass between 4 and 8 GeV (low), a WIMP with mass around 60-70 GeV (middle) and a heavy WIMP with mass above 500 GeV (high). In the first case, we show that capture in the Sun may be constrained using Super-Kamiokande data. In the last two cases, we argue that indirect detection through neutrinos is challenging but not altogether excluded. For middle masses, we try to make the most benefit of the proximity of the so-called 'iron resonance' that might enhance the capture of the dark matter candidate by the Earth. The signal from the Earth is further enhanced if light right-handed Majorana neutrinos are introduced, in which case the scalar dark matter candidate may annihilate into pairs of mono-energetic neutrinos. In the case of high masses, detection of neutrinos from the Galactic centre might be possible, provided the dark matter abundance is substantially boosted.

Figures (13)

• Figure 1: Scattering of $H_0$ on a nucleus $\mathcal{N}$ through exchange of a Higgs boson $h$.
• Figure 2: Typical behaviour of ${\cal F}_{\odot/\oplus}$ in function of $m_{H_0}$ for Sun (dashed blue line) and Earth (solid black line). The resonance phenomenon, which is present for elements in the Earth, is absent for the Sun (here for $m_h=120 \; \mathrm{GeV}$, $f=0.3$ and $\lambda_L=0.2$).
• Figure 3: The only tree level annihilation channel of light $H_0$ ($m_{H_0} \lesssim m_W$) into fermions pairs is through the Higgs boson.
• Figure 4: Expected neutrino (left) and muon (right) fluxes from the Sun, for a neutrino energy threshold of 2 GeV. Dark blue line in the muon flux plot: estimate of Super-Kamiokande sensitivity, conservatively extrapolated to light WIMPs (see text). Colour gradient - $\, \log_{10} \phi_\nu ~ [\textsl{km}^{-2} \, \textsl{yr}^{-1}]$ (left) and $\log_{10} \phi_\mu ~ [\textsl{km}^{-2} \, \textsl{yr}^{-1}]$ (right); WMAP area (black lines); DAMA allowed region (dashed magenta lines); XENON, CDMS exclusion limits (white lines, from left to right); The shaded regions correspond to $\lambda_2 > 1$. (Parameters: $m_h = 120 \, \textsl{GeV}$, $\lambda_2 = 1$ (dotted) and $\lambda_2 = \pi$ (shaded), $f = 0.3$).
• Figure 5: The region allowed by DAMA (dashed magenta lines) together with limits on the spin-independent elastic scattering cross section of $H_0$ on a nucleus from direct detection experiments (dash-dotted green lines), cf. Petriello:2008jj. Super-Kamiokande (solid blue line) sets another limit from the $\tau^+\tau^-$ annihilation channel of $H_0$. This limit results from the one presented in Hooper:2008cf rescaled by the IDM branching ratio.