New scenario for aligned Higgs couplings originated from the twisted custodial symmetry at high energies

We investigate a new scenario of the two Higgs doublet model, where the current experimental data for the electroweak rho parameter and those for the Higgs boson couplings can be simultaneously explained. In this scenario, the two Higgs doublet model is supposed to be a low energy effective theory up to a high energy scale Λ, above which a fundamental theory should appear. It is assumed that the Higgs potential respects a global symmetry at Λ (the twisted custodial symmetry), which is to be given as a consequence of the global symmetry structure of the fundamental theory above Λ. By the analysis using one-loop renormalization group equations, the above experimental data can be explained in a natural way even when the masses of the extra Higgs bosons are near the electroweak scale. We also discuss the predictions on the mass spectrum of the additional Higgs bosons and also those on the coupling constants of the standard-model-like Higgs boson, which make it possible to test this scenario at the current and future collider experiments.

E6 inspired SUSY models with custodial symmetry

The breakdown of [Formula: see text] within the supersymmetric (SUSY) Grand Unified Theories (GUTs) can result in SUSY extensions of the standard model (SM) based on the SM gauge group together with extra [Formula: see text] gauge symmetry under which right-handed neutrinos have zero charge. In these [Formula: see text] extensions of the minimal supersymmetric standard model (MSSM) a single discrete [Formula: see text] symmetry may be used to suppress the most dangerous operators, that give rise to proton decay as well as nondiagonal flavour transitions at low energies. The SUSY models under consideration involves [Formula: see text] and extra exotic matter beyond the MSSM. We discuss leptogenesis within this SUSY model and argue that the extra exotic states may lead to the nonstandard Higgs decays.

Impacts of multi-Higgs on the ρ parameter, decays of a neutral Higgs to WW and ZZ, and a charged Higgs to WZ

In the Standard Model (SM), the [Formula: see text] parameter is equal to 1 and the ratio [Formula: see text] of Higgs [Formula: see text] and Higgs [Formula: see text] is also equal to 1 at the tree level. When going beyond the SM with more than one type of Higgs representations, these quantities may be different from the SM predictions which can provide crucial information about new physics. There may also exist a certain charged Higgs [Formula: see text] decays into a [Formula: see text] and a [Formula: see text]. Imposing a custodial symmetry can force the parameter [Formula: see text] to be equal to 1 with certain predictions for [Formula: see text] and [Formula: see text]. However, imposing [Formula: see text] without custodial symmetry may have different predictions. We show how differences arise and how to use experimental data to obtain information about the underlying physics in a model with the SM, plus a real and a complex [Formula: see text] triplet.