New features in the Z2xZ2 3HDM two component DM model

TL;DR

The paper investigates a $Z_{2}\times Z_{2}$-symmetric three-Higgs-doublet model with two inert doublets that realize a two-component DM scenario. It develops a comprehensive theoretical framework, deriving sufficient BFB conditions via a copositive $3\times3$ matrix and performing a global-minimum analysis across neutral and charged vacua, including new minima $\text{F0DM0'}$ and $\text{F0CB}$. A broad 15-parameter scan under collider, EW precision, and DM constraints reveals viable regions where both DM components contribute to the relic density, with equal-abundance cases in specific mass ranges such as $\tfrac{1}{2}m_h< m_{H_1} < 80$ GeV or $m_{H_1}\gtrsim 500$ GeV. The work emphasizes the rich DM phenomenology of multi-component DM in extended Higgs sectors and highlights the need for complementary probes as direct-detection reach approaches the neutrino floor.

Abstract

We investigate the constraints and phenomenology of a three Higgs doublet model (3HDM) with a $\Z2\times\Z2$ symmetry, featuring two inert scalar doublets that give rise to a two-component dark matter (DM) scenario. We analyze the model's vacuum structure, exploring the competition between different symmetry-breaking minima, and subject it to comprehensive theoretical and current experimental constraints. Our analysis reveals previously unexplored regions of parameter space with viable dark matter candidates. Notably, we identify scenarios where both DM particles contribute comparably to the observed relic density, offering distinctive experimental signatures that could guide future searches.

Figures (3)

• Figure 2: Direct detection constraints on $H_1$ ($H_2$) on the left (right) figure. See text for details.
• Figure 3: The colours of the points have the same meaning as in Fig. \ref{['direct']}. The left figure shows the total $\langle\sigma v\rangle$ as a function of $m_{H_1}$. The right figure shows the dominant contribution to $\langle\sigma v\rangle$ as a function of the mass of the DM candidate, $m_\textrm{DM}$, which corresponds to the $\langle\sigma v\rangle$ plotted on the vertical axis. The lines coming from Fermi-LAT Fermi-LAT:2015att and H.E.S.S. HESS:2022ygk assume a Navarro-Frenk-White (NFW) DM density profile and the AMS-02 AMS:2016oqu lines correspond to the conservative approach derived in Ref. Reinert:2017aga, with the colour codes also shown in the figure.
• Figure 4: Range of allowed ($m_{H_1}, m_{H_2}$) masses with a "temperature" colour code for $\Omega_1/\Omega_T$ ($\Omega_2/\Omega_T$) on the left (right).