Yukawa alignment in the two-Higgs-doublet model

Abstract

In multi-Higgs-doublet models the alignment in flavour space of the relevant Yukawa matrices guarantees the absence of tree-level flavour-changing couplings of the neutral scalar fields. We analyze the consequences of this condition within the two-Higgs-doublet model and show that it leads to a generic Yukawa structure which contains as particular cases all known specific implementations of the model based on Z2 symmetries. All possible freedom in the Yukawa sector gets parametrized in terms of three complex couplings ς f . In spite of having flavour conservation in the neutral scalar couplings, the phases of these three parameters represent potential new sources of CP violation.

Preserving the validity of the two-Higgs-doublet model up to the Planck scale

“…We focus on the decoupling regime of the 2HDM where the 125 GeV Higgs boson is SM-like [36,37], and assume Yukawa alignment in the flavor sector [38] to avoid Higgs-mediated tree-level FCNCs. Our aim is to exhibit the allowed regions of the 2HDM parameter space that are free from both Landau poles and vacuum instability below the Planck scale.…”

“…In order to circumvent this, we impose a "flavor alignment ansatz", introduced in Ref. [38], which postulates that the independent matrix Yukawa couplings are proportional to the corresponding quark and charged lepton mass matrices. In this case one finds that, in the mass basis for the quarks and leptons, the matrix Yukawa couplings are flavor diagonal, and the Higgs-mediated tree-level FCNCs are absent.…”

Status of B to D(*) τ ν decays in two-Higgs-doublet models

“…In this talk I will show that to accommodate the latest BaBar measurement of R(D * ) within this model, a departure from the family universality of the Yukawa couplings is required. With this purpose in mind, the current excess in R(D ( * ) ) is analyzed within the Aligned two-Higgs-doublet model (A2HDM) [8], taking into account other meson decays in which the charged Higgs enters also at tree level. The processes considered are listed in Table 2, a more detailed discussion of the results presented here can be found in Refs.…”

The muon magnetic moment in the 2HDM: complete two-loop result

“…In the Aligned 2HDM it is only required that the mass matrices and the Yukawa coupling matrices in the most general Yukawa Lagrangian are proportional to each other with proportionality constant, ζ f [68]. The aligned Yukawa Lagrangian reads…”