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 →Dτν, plus B →X _s γ, including B ⁰− $\overline{B}$ ⁰ mixing, B _s → μ ⁺ μ ⁻ and the radiative decay Z → b $\overline{b}$. Thirdly, having selected the surviving 2HDM-III parameter space, we show that the H ⁻ c $\overline{b}$ 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., $\mathcal{Z}$ 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 c $\overline{b}$ → H ⁺ production mode and the H ⁺ → c $\overline{b}$ 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.