Effect of the Flavor Changing Neutral Current on Rare B decays

We study the effect of the FCNC on rare $B$ decays in the beyond standard model with vector like singlet quarks. It has been shown that $b \rightarrow s \gamma $ does not receive sizable contribution compared with that of the standard model while $b \rightarrow d \gamma $, $b \rightarrow s(d) l^+ l^-$, can be changed from the predictions of the standard model.