We investigate the collider phenomenology of the scalar triplet particles in the Type-II seesaw model at a 100 TeV pp collider. Depending on triplet vacuum expectation value v∆, the dominant discovery channels could be H ++ H −− and H ±± H ∓ . We find the H ±± H ∓ → W ± W ± hW ∓ / ± ± hW ∓ channels are promising for both model discovery at relatively large v∆ and determination of the Higgs portal couplings λ4 and λ5. We also find that these two channels are complementary to indirect determination of λ4 from future precise measurements on h → γγ decay rate. Together with pair production of the doubly-charged Higgs subsequently decaying into same-sign di-leptons, the H ±± H ∓ channels have the potential to cover a significant portion of the parameter space of the Type-II seesaw complex scalar triplet model. *

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We derive a general low-energy theory for twisted moiré heterostructures comprised of Dirac materials. We apply our theory to heterostructures on the surface of a three dimensional topological insulator (3D TI). First, we consider the interface between two 3D TIs arranged with a relative twist angle. We prove that if the two TIs are identical, then a necessary condition for a perturbative magic angle where the Dirac cone velocity vanishes is to have an interlayer spin-flipping hopping term. Without this term, the Dirac cone velocities can still be significantly renormalized, decreasing to less than half of their original values, but they will not vanish. Second, we consider graphene on the surface of a TI arranged with a small twist angle. Again, a magic angle is unachievable with only a spin-flipping hopping term; under such conditions, the Dirac cone is renormalized, but only moderately. In both cases, our perturbative results are verified by computing the band structure of the continuum model. The enhanced density of states that results from decreasing the surface Dirac cone velocity provides a tunable route to realizing interacting topological phases.

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