Inclusive dileptonic rareBdecays with an extra generation of vectorlike quarks

We investigate the leading effects of extending the standard model of electroweak interactions by an extra isosinglet up- and down-type quark pair on various distributions and total branching ratio of the inclusive $\overrightarrow{B}{X}_s{l}^{+}{l}^{-}$ $(l=e,\mu )$ rare B decays. The presence of the extra vectorlike down quark D results in the nonunitarity of the extended quark mixing matrix V, which in turn leads to $\overrightarrow{b}s$ flavor changing neutral currents at the tree level proportional to ${(V}^{†}{V)}_{\mathrm{sb}}.$ On the other hand, the effective penguin and box vertex functions are sensitive to the mass of the extra isosinglet up quark $m_U.$ The experimental upper bound on $BR\left(\overrightarrow{B}{X}_s{\mu }^{+}{\mu }^{-}\right)$ is used to constrain the parameters of the model. It is shown that the shapes of the differential branching ratio and forward-backward asymmetry distribution are very sensitive to the value of the model parameters. We also calculate the $\mathrm{CP}$ aymmetry distribution of the dileptonic decay in the vectorlike quark model. It is shown that, for a typical choice of the model parameters, asymmetries up to around 10% can be achieved for certain values of the dilepton invariant mass.