Contributions of Vector-Like Quarks to $B\to X_s\gamma$ and $B_s^0{\bar{B}}_s^0$ Mixing

Abstract

The radiative decay $\text{BSgamma}$ and the mixing $\text{BsBs}$ are discussed in the vector-like quark model which contains extra SU(2)-singlet quarks with the same electric charges as the up-type and down-type quarks. Constraints on the extended Cabibbo-Kobayashi-Maskawa matrix are obtained from the experimental results for the branching ratio of $\text{BSgamma}$ . Within these experimental bounds, any value of the branching ratio can be accounted for by the contributions from the vector-like quarks. In sizable ranges of the model parameters, the mixing parameter for $\text{BsBs}$ is much different from the prediction of the standard model.

Comments: 4 pages, LATEX file with 3 EPS figures. To appear in the proceedings of BCP4, Ise-Shima, Japan, 18-23 Feb 2001