T. Affolder et al., First measurement of the ratio B(t -> Wb)/B(t -> Wq) and associated limit on the Cabibbo-Kobayashi-Maskawa element vertical bar V-tb vertical bar, PHYS REV L, 86(15), 2001, pp. 3233-3238
We present the first measurement of the ratio of branching fractions R equi
valent to B(t --> Wb)/B(t --> Wq) from pa collisions at roots = 1.8 TeV. Th
e data set corresponds to 109 pb(-1) of data recorded by the Collider Detec
tor at Fermilab during the 1992-95 Tevatron run. We measure R = 0.94(-0.24)
(+0.31)(stat + syst) or R > 0.61 (0.56) at 90% (95)% C.L., in agreement wit
h the standard model predictions. This measurement yields a limit on the Ca
bibbo-Kobayashi-Maskawa quark mixing matrix element \V-tb\ under the assump
tion of three generations and unitarity.