Exclusive radiativeB-meson decays within minimal flavor-violating two-Higgs-doublet models

Abstract

In the "Higgs basis" for a generic 2HDM, only one doublet gets a nonzero vacuum expectation value and, under the criterion of minimal flavour violation, the other one is fixed to be either colour-singlet or colour-octet, referred to, respectively, as the type-III and type-C models. Both of them can naturally avoid large FCNC transitions and provide very interesting phenomena in some low-energy processes. In this paper, we study their effects on exclusive radiative B-meson decays due to the exchange of colourless or coloured charged Higgs. It is found that, while constraints from the branching ratios are slightly weaker than the ones from the inclusive B → X s γ decay, the isospin asymmetries in exclusive decays provide very complementary bounds on the model parameters. As the two models predict similar corrections to the dipole coefficient C eff 7 , but similar magnitudes with with opposite signs to C eff 8 , the branching ratios cannot discriminate the two models, and we have to resort to the direct CP and isospin asymmetries of b → s processes, which are more sensitive to C eff 8 . Due to the CKM factors |λt |, the terms proportional to λ provide further insights into the models with more precise experimental measurements and theoretical predictions for these decays.

K0-K¯0 Mixing in the Minimal Flavor-Violating Two-Higgs-Doublet Models

“…The relevant model parameters are also constrained by the other processes. For the parameter | 푢 |, an upper bound can be obtained from the → decay [25], while the parameter 푑 is much less constrained phenomenologically [25,28]. However, the perturbativity of the theory requires that these couplings cannot be too large.…”

“…Transforming the Lagrangian in (1) from the interaction basis to the mass basis, one can obtain the Yukawa interactions of charged Higgs with quarks in the mass-eigenstate basis, which are given by [25,28] …”

“…The neutral-meson mixings are of particular interest in this respect, because the charged-Higgs contributions to these processes arise at the same order as does the boson in the SM, indicating that the NP effects might be significant. For example, the chargedHiggs effects of these two models on the 0 푠 − 0 푠 mixing have been studied in [28]. In this paper, we shall explore the 0 − 0 mixing within these two models and pursue possible differences between their effects.…”

“…Although the scalar-mediated flavor-violating interactions are protected by the MFV hypothesis, type III and type C models can still bring in many interesting phenomena in some low-energy processes, especially due to the presence of a charged-Higgs boson [24,25,[28][29][30][31][32]. The neutral-meson mixings are of particular interest in this respect, because the charged-Higgs contributions to these processes arise at the same order as does the boson in the SM, indicating that the NP effects might be significant.…”

Perturbed Lepton-Specific Two-Higgs-Doublet Model Facing Experimental Hints for Physics beyond the Standard Model

“…Models solving the RðDÞ puzzle have been discussed extensively in the literature [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59], including the possibility of charged scalars [46,48,49,60]. For τ → μνν, the dominant uncertainty in the SM prediction for the branching ratio comes from the τ lifetime τ τ .…”