MEASUREMENT OF THE B-]TAU(-)(NU)OVER-BAR-(TAU)X BRANCHING RATIO AND AN UPPER LIMIT ON B--]TAU(-)(NU)OVER-BAR-(TAU)

Using 1.45 million hadronic Z decays collected by the ALEPH experiment at LEP, the b --> tau(-) ($) over bar V(tau)X branching ratio is measured to be 2.75 +/- 0.30 +/- 0.37%. In addition an upper limit of 1.8 x 10(-3) at 90% confidence level is placed upon the exclusive branching ratio of B- --> tau(-)($) over bar V-tau. These measurements are consistent with SM expectations, and put the constraint tan beta/M(H+) < 0.52 GeV-1 at 90% confidence level on all Type II two Higgs doublet models (such as the MSSM).