Dark matter and neutrino masses from a scale-invariant multi-Higgs portal

TL;DR

The paper develops a classically scale-invariant extension of the Standard Model by adding a dark SU(2)_X gauge sector, a dark scalar doublet, a real singlet, and right-handed neutrinos. Using Coleman-Weinberg radiative breaking and the Gildener-Weinberg formalism, it analyzes the resulting three-scalar system and the three dark gauge bosons, which become stable vector dark matter, while neutrino masses arise from a low-energy seesaw mediated by the singlet. The authors demonstrate vacuum stability and perturbativity up to the Planck scale, identify viable benchmark parameters that reproduce the observed Higgs mass $M_h\approx 125.09$ GeV, and find a dark-matter mass window $M_X\approx 710$–$740$ GeV that saturates the relic density; direct-detection prospects lie within reach of upcoming experiments such as XENON1T. The framework yields concrete, testable predictions for collider searches of extra scalars and for direct-detection experiments, enabling near-future falsification or validation of the model.

Abstract

We consider a classically scale invariant version of the Standard Model, extended by an extra dark $SU(2)_X$ gauge group. Apart from the dark gauge bosons and a dark scalar doublet which is coupled to the Standard Model Higgs through a portal coupling, we incorporate right-handed neutrinos and an additional real singlet scalar field. After symmetry breaking à la Coleman-Weinberg, we examine the multi-Higgs sector and impose theoretical and experimental constraints. In addition, by computing the dark matter relic abundance and the spin-independent scattering cross section off a nucleon we determine the viable dark matter mass range in accordance with present limits. The model can be tested in the near future by collider experiments and direct detection searches such as XENON 1T.

Figures (9)

• Figure 1: (color online). Parameter space scan in the plane $(g_X,Y_\sigma)$, taking into account constraints from stability and perturbativity. The color coding signifies the mass of the darkon $M_{h_2}$.
• Figure 2: (color online). The RG evolution of the scalar couplings at two-loop order for $M_N = 240\,\, \; \mathrm{GeV}$ and $M_X = 725\,\, \; \mathrm{GeV}$.
• Figure 3: Feynman diagrams for DM annihilation to gauge bosons and fermions.
• Figure 4: Feynman diagrams for DM annihilation to scalars.
• Figure 5: Feynman diagrams for DM semiannihilation.