High scale impact in alignment and decoupling in two-Higgs-doublet models

Abstract

The two-Higgs-doublet model (2HDM) provides an excellent benchmark to study physics beyond the Standard Model (SM). In this work, we discuss how the behavior of the model at high-energy scales causes it to have a scalar with properties very similar to those of the SM-which means the 2HDM can be seen to naturally favor a decoupling or alignment limit. For a type II 2HDM, we show that requiring the model to be theoretically valid up to a scale of 1 TeV, by studying the renormalization group equations (RGE) of the parameters of the model, causes a significant reduction in the allowed magnitude of the quartic couplings. This, combined with B-physics bounds, forces the model to be naturally decoupled. As a consequence, any nondecoupling limits in type II, like the wrong-sign scenario, are excluded. On the contrary, even with the very constraining limits for the Higgs couplings from the LHC, the type I model can deviate substantially from alignment. An RGE analysis similar to that made for type II shows, however, that requiring a single scalar to be heavier than about 500 GeV would be sufficient for the model to be decoupled. Finally, we show that the 2HDM is stable up to the Planck scale independently of which of the CP-even scalars is the discovered 125 GeV Higgs boson.

High scale validity of the DFSZ axion model with precision

“…We refer to these two conditions as the high scale validity. Similar discussions can be found in the context of THDMs [21][22][23][24][25][26][27][28][29][30][31][32][33]. As we will see and as found in the previous studies, these conditions are complementary and become very restrictive if combined.…”

b → sℓ+ℓ− transitions in two-Higgs-doublet models

“…Ref. [9,10,11,12,13,14,15,16,17] for recent reports). In addition, they give rise to important effects in low-energy precision flavour observables, providing a complementary window to physics beyond the SM.…”

Singlet-doublet fermionic dark matter and gravitational waves in a two-Higgs-doublet extension of the Standard Model

“…The model with such a modified scalar sector thus resembles with the standard two Higgs doublet model (2HDM) of Type-I [18,[20][21][22], where all SM fermions have Yukawa interactions with only one of the doublets e.g., Φ 2 . The most general renormalizable scalar potential can then be written as:…”

“…Tree-level unitarity imposes bounds on the size of the quartic couplings λ i or various combinations of them. The quartic couplings and the Yukawa couplings appearing in the theory need to satisfy [21,22,97]:…”