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Register a new userSinglet portal extensions of the standard seesaw models to dark sector with local dark symmetry: An alternative to the new minimal standard model
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Assuming dark matter is absolutely stable due to unbroken dark gauge symmetry and singlet operators are portals to the dark sector, we present a simple extension of the standard seesaw model that can accommodate all the cosmological observations as well as terrestrial experiments available as of now, including leptogenesis, extra dark radiation of $sim 0.08$ (resulting in $N_{rm eff} = 3.130$ the effective number of neutrino species), Higgs inflation, small and large scale structure formation, and current relic density of scalar DM ($X$). The Higgs signal strength is equal to one as in the SM for unbroken $U(1)_X$ case with a scalar dark matter, but it could be less than one independent of decay channels if the dark matter is a dark sector fermion or if $U(1)_X$ is spontaneously broken, because of a mixing with a new neutral scalar boson in the models.
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We find that the nonperturbative physics of the standard-model Higgs Lagrangian provides a dark matter candidate, dormant skyrmion in the standard model, the same type of the skyrmion, a soliton, as in the hadron physics. It is stabilized by another nonperturbative object in the standard model, the dynamical gauge boson of the hidden local symmetry, which is also an analogue of the rho meson.
We consider generation of dark matter mass via radiative electroweak symmetry breaking in an extension of the conformal Standard Model containing a singlet scalar field with a Higgs portal interaction. Generating the mass from a sequential process of radiative electroweak symmetry breaking followed by a conventional Higgs mechanism can account for less than 35% of the cosmological dark matter abundance for dark matter mass $M_s>80 GeV$. However in a dynamical approach where both Higgs and scalar singlet masses are generated via radiative electroweak symmetry breaking we obtain much higher levels of dark matter abundance. At one-loop level we find abundances of 10%--100% with $106 GeV<M_s<120 GeV$. However, when the higher-order effects needed for consistency with a $125 GeV$ Higgs mass are estimated, the abundance becomes 10%--80% for $80 GeV<M_s<96 GeV$, representing a significant decrease in the dark matter mass. The dynamical approach also predicts a small scalar-singlet self-coupling, providing a natural explanation for the astrophysical observations that place upper bounds on dark matter self-interaction. The predictions in all three approaches are within the $M_s>80 GeV$ detection region of the next generation XENON experiment.
We consider here three dark matter models with the gauge symmetry of the standard model plus an additional local $U(1)_D$ factor. One model is truly secluded and the other two models begin flipped, but end up secluded. All of these models include one dark fermion and one vector boson that gains mass via the Stueckelberg mechanism. We show that the would be flipped models provide an example dark matter composed of almost least interacting particles (ALIPs). Such particles are therefore compatible with the constraints obtained from both laboratory measurements and astrophysical observations.
In any gauge extension of the standard model (SM) of quarks and leptons, there is a minimal set of fermion and scalar multiplets which encompasses all the particles and interactions of the SM. Included within this set, there may be a suitable dark-matter candidate. If not, one may still exist from the judicious addition of a simple fermion or scalar multiplet without any imposed symmetry. Some new examples of such predestined dark matter are discussed.
We study electroweak scale Dark Matter (DM) whose interactions with baryonic matter are mediated by a heavy anomalous $Z$. We emphasize that when the DM is a Majorana particle, its low-velocity annihilations are dominated by loop suppressed annihilations into the gauge bosons, rather than by p-wave or chirally suppressed annihilations into the SM fermions. Because the $Z$ is anomalous, these kinds of DM models can be realized only as effective field theories (EFTs) with a well-defined cutoff, where heavy spectator fermions restore gauge invariance at high energies. We formulate these EFTs, estimate their cutoff and properly take into account the effect of the Chern-Simons terms one obtains after the spectator fermions are integrated out. We find that, while for light DM collider and direct detection experiments usually provide the strongest bounds, the bounds at higher masses are heavily dominated by indirect detection experiments, due to strong annihilation into $W^+W^-$, $ZZ$, $Zgamma$ and possibly into $gg$ and $gammagamma$. We emphasize that these annihilation channels are generically significant because of the structure of the EFT, and therefore these models are prone to strong indirect detection constraints. Even though we focus on selected $Z$ models for illustrative purposes, our setup is completely generic and can be used for analyzing the predictions of any anomalous $Z$-mediated DM model with arbitrary charges.
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