Fourth generation effects in the B-s -> nu(nu)over-bar gamma decay

If the fourth generation fermions exist, the new quarks could influence the branching ratio of the decay B-s --> <<nu>(nu )over bar gamma>. We obtain two solutions of the fourth generation CKM factor V-t 's*V-t 'b from the de cay of B --> X(s)gamma. With these two solutions we calculate the new contr ibutions of the fourth generation quark to Wilson coefficients of the decay Bs --> <<nu>(nu )over bar gamma>. The branching ratio of the decay Bs --> <<nu>(nu )over bar gamma> in the two cases are calculated. In one case, our results are quite different from that of SM, but almost same in another ca se. If a fourth generation should exist in nature and nature chooses the fo rmer case, this B meson decay could provide a possible test of the fourth g eneration existence. (C) 2001 Elsevier Science B.V. All rights reserved.