Improving bounds on flavor changing vertices in the two Higgs doublet model from $B-\bar{B}$ mixing

Abstract

We find some constraints on the flavor changing vertices of the two Higgs doublet model, from the ΔM_{B_{d}} measurement. Although bounds from this observable have already been considered, this paper takes into account the role of a new operator not included previously, as well as the vertices ξ_{bb}, ξ_{tc} and ξ_{sb}. Using the Cheng-Sher parametrization, we found that for a relatively light charged Higgs boson (200-300 GeV), we get that λ_{tt}<1, while the parameter λ_{bb} could have values up to about 50. In addition, we use bounds for λ_{tt} and λ_{bb} obtained from B^{0}->X_{s}γat next to leading order, and studied the case where the only vanishing vertex factors are the ones involving quarks from the first family. We obtained that ΔM_{B_{d}} is not sensitive to the change of the parameter λ_{sb}, while λ_{tc}<1