Higgs-induced flavor-changing neutral current as a source of new Physics in b→s transitions

Abstract

The experimental study of B mesons suggest the existence of some new physics contribution to the B_s⁰-B̅ _s⁰ mixing. We study the implications of a hypothesis that this contribution is generated by the Higgs-induced flavor-changing neutral currents (FCNC). We concentrate on the specific b→s transition which is described by two complex FCNC parameters, F₂₃ and F₃₂, and parameters in the Higgs sector. Model-independent constraints on these parameters are derived from the B_s⁰-B̅_s⁰ mixing and are used to predict the branching ratios for B̅_s→ μ⁺μ̅ and B̅ _d→ K̅ μ⁺μ^- numerically by considering general variations in the Higgs parameters assuming that Higgs sector conserves CP. Taking the results on B_s⁰-B̅_s⁰ mixing derived by the global analysis of UTfit group as a guide we present the general constraints on F₂₃∗ F₃₂ in terms of the pseudoscalar mass M_A. The former is required to be in the range ˜(1-5)×10^-11M_A²GeV^-2 if the Higgs-induced FCNC represent the dominant source of new physics. The phases of these couplings can account for the large CP violating phase in the B_s⁰-B̅ _s⁰ mixing except when F₂₃=F₃₂. The Higgs contribution to B̅_s→μ⁺μ^- branching ratio can be large, close to the present limit while it remains close to the standard model value in case of the process B̅_d→ K̅μ⁺μ^- for all the models under study. We identify and discuss various specific examples which can naturally lead to suppressed FCNC in the K⁰-K̅ ⁰ mixing allowing at the same time the required values for F₂₃∗ and F₃₂.