Fe b 20 03 Fourth generation effects in rare B s → l + l − and B s → l + l − γ decays

The contribution of the fourth generation quarks to the rare Bs → l+l− and Bs → l+l−γ decays are studied. Constraints on the extended Cabibbo–Kobayashi–Maskawa matrix elements |VtbV ∗ ts| and |Vt′bV ∗ t′s| are obtained from the existing experimental result for the branching ratio of the B → Xsγ decay. The branching ratios of the above–mentioned decays, as well as the photon spectrum in the Bs → l+l−γ decay, are studied. It is found that the results are sensitive to the existence of the fourth generation. PACS number(s): 12.60.–i, 13.20.–v, 13.20.He e-mail: [email protected] e-mail: [email protected] e-mail: [email protected]