Constraints on the quark mixing matrix with vector-like quarks

While a chiral fourth generation of quarks is almost ruled out from the data on Higgs boson production and decay at the Large Hadron Collider, vector-like quarks are still a feasible option to extend the fermionic sector of the Standard Model. Such an extension does not suffer from any anomalies and easily passes the constraints coming from oblique electroweak parameters. We consider such minimal extensions with $SU(2)$ singlet and doublet vector-like quarks that may mix with one, or at the most two, of the Standard Model quarks. Constraints on the new mixing angles and phases are obtained from several $\Delta B = 1$ and $\Delta B = 2$ processes.