Off-diagonal terms in Yukawa textures of the Type-III 2-Higgs doublet model and light charged Higgs boson phenomenology

Abstract

We discuss flavor-violating constraints and consequently possible charged Higgs boson phenomenology emerging from a four-zero Yukawa texture embedded within the Type-III 2-Higgs Doublet Model (2HDM-III). Firstly, we show in detail how we can obtain several kinds of 2HDMs when some parameters in the Yukawa texture are absent. Secondly, we present a comprehensive study of the main B-physics constraints on such parameters induced by flavor-changing processes, in particular on the off-diagonal terms of such a texture: i.e., from µ − e universality in τ decays, several leptonic B-decays (B → τ ν, D → µν and D s → lν), the semi-leptonic transition B → Dτ ν, plus B → X s γ, including B 0 −B 0 mixing, B s → µ + µ − and the radiative decay Z → bb. Thirdly, having selected the surviving 2HDM-III parameter space, we show that the H − cb coupling can be very large over sizable expanses of it, in fact, a very different situation with respect to 2HDMs with a flavor discrete symmetry (i.e., Z 2 ) and very similar to the case of the Aligned-2HDM (A2HDM) as well as of models with three or more Higgs doublets. Fourthly, we study in detail the ensuing H ± phenomenology at the Large Hadron Collider (LHC), chiefly the cb → H + production mode and the H + → cb decay channel while assuming τ + ν τ decays in the former and t → bH + production in the latter, showing that significant scope exists in both cases.

Flavor violating signatures of lighter and heavier Higgs bosons within Two Higgs Doublet Model type III at the LHeC

“…Since a specific four-zero texture is implemented as a flavor symmetry in the Yukawa sector, this is the mechanism which controls FCNCs so that discrete symmetries in the Higgs potential are not needed [8][9][10][11][12]. Then the most general SU (2) L × U (1) Y invariant scalar potential, following [7], can be written where φ f ij (φ = h, H, A), Xij , Yij and Zij are defined as follows:…”

“…where f (x) = √ 1 + x 2 , ξ f φ are related to the trigonometric ratios (i.e., cos α/ sin β, sin α/ sin β, cos α/ cos β, sin α/ cos β) and the parameters X, Y and Z can be related to tan β or cot β, according to the various incarnations of 2HDMs [10] (see the Table I). Taking into account that the Higgs-fermion-fermion (φf f ) coupling in the 2HDM-III is written as g…”

“…−any is the coupling φf f in some of the 2HDMs with discrete symmetry and ∆g is the contribution of the four-zero texture 5 , it was pointed out in [10] that this Lagrangian could also represent a Multi-Higgs Doublet Model (MHDM) or an Aligned 2HDM (A2HDM) with additional flavor physics in the Yukawa matrices. Here, we consider three different incarnations of the 2HDM-III, which correspond to to the four 2HDM types already described except the lepton specific one, as here leptonic Branching Ratios (BRs) are dominant, whereas we intend to look for an enhancement in the Higgs to bs decay because of flavor violation.…”

“…As for the experimental ones, we have taken into account recent experimental bounds from flavor physics [9,10]: i.e., from B → τ ν τ , D → µν, D s → ℓν, the semileptonic transition B → Dτ ν τ , the inclusive decay B → X s γ, B 0 − B 0 mixing, B s → µ + µ − and the radiative decay Z → bb. (We have also imposed EWPO limits.)…”

“…[8][9][10][11][12][13][14][15]. However, plentiful of studies, also including lepton flavor violating scenarios, exist, some specific to 2HDMs and others adaptable to their case: see for an incomplete list, e.g., Refs.…”