The role of charged Higgs boson decays in the determination of tan β-like parameters

Abstract

The most commonly used parameterizations of the Yukawa couplings in the two Higgs doublet model are revisited. Their similitudes and differences are emphasized and relations between the different notations used in the literature are derived. Using these relations, bounds on the space of parameters of the charged Higgs sector of the two Higgs doublet model are obtained. These constraints are obtained from flavor observables like the measurement of B → X s γ and the recent measurement of B s → µ + µ − from LHCb. The ratio R H + = B(H + → τ +ν τ )/B(H + → tb) is evaluated for the two Higgs doublet model type-III and type-II, and their differences are quantified.One simple framework beyond the standard model (SM) consists in adding a Higgs doublet, leading to a rich Higgs sector spectrum and therefore, giving a richer phenomenology than in the SM [1,2]. This model is usually called the Two Higgs doublet Model (THDM). In the THDM there are three Goldstone bosons that give masses to the gauge bosons and there are also five Higgs bosons: two CP-even neutral Higgs bosons, one CP-odd neutral Higgs boson and two charged Higgs bosons.There are multiple ways to implement this kind of SM extension. These ways depend on how the couplings between the Higgs bosons and the fermions are chosen. They should be chosen carefully in order to avoid Flavor Changing Neutral Currents (FCNC) which are generated at the tree level in the most general version of the THDM, the so called type-III THDM. In contrast, models like the type-I and II THDM impose an additional discrete symmetry in order to avoid the FCNC at tree level [2]. In the type-I model, the couplings between the Higgs bosons and the fermions are chosen such that only one Higgs doublet couples to the SM fermions, whereas in the type-II model, one doublet couples with the up quark sector and the another one with the down quark sector. In the type-III model, although both Higgs doublets couple with the SM fermions, the model is still phenomenologically possible if the FCNC at tree level are suppressed [3].The THDM type-II has been studied more extensively in the literature, motivated by its similarities in the Higgs sector at tree level with the Minimal Supersymmetric Standard Model (MSSM), which requires a second Higgs doublet. However, due to quantum loop corrections, the Higgs sector will actually be described by an effective potential which is similar to the most general version of the THDM, the so-called type-III.From a phenomenological point of view, it is important to study the properties of the most general THDM. In this model, there are two Yukawa matrices per fermion type (up or down type quarks and leptons) which cannot be diagonalized simultaneously. There are two different ways to deal with the 1 arXiv:1205.5726v1 [hep-ph]