Flavor Changing Neutral Higgs Bosons in a Supersymmetric Extension based on a $Q_6$ Family Symmetry

Abstract

A supersymmetric extension of the standard model based on the discrete $Q_6$ family symmetry is considered, and we investigate flavor-changing neutral current (FCNC) processes, especially those mediated by heavy flavor-changing neutral Higgs bosons. Because of the family symmetry the number of the independent Yukawa couplings is smaller than that of the observed quantities such as the Cabibbo-Kobayashi-Maskawa matrix and the quark masses, so that the FCNCs can be parametrized only by the mixing angles and masses of the Higgs fields. We focus our attention on the mass differences of the neutral $K, D$ and $B$ mesons. All the constraints including that from the ratio $ΔM_{B_s}/ΔM_{B_d}$ can be satisfied, if the heavy Higgs bosons are heavier than $\sim 1.5$ TeV. If the constraint from $ΔM_K$ is slightly relaxed, the heavy Higgs bosons can be as light as $\sim 0.4$ TeV, which is within the accessible range of LHC.