Exclusive Semi-leptonic Decays b → s ( d )νν̄ in the Standard Model with Fourth Generation

We consider the effects of the fourth generation quarks on the rare B decay processes described by the b ? s(d)??? processes at the quark level. We find that the values of the branching ratios for some of these rare decay processes are much larger than the standard model (SM) predictions. These processes can be used to constrain the relevant free parameters.