A measurement of the product branching ratio f(b -> Lambda(b)) center dot BR(Lambda(b) -> Lambda X) in Z(0) decays

The product branching ratio, f(b --> Lambda(b)) . BR(Lambda(b) --> Lambda X), where Lambda(b) denotes any weakly-decaying b-baryon, has been measured using the OPAL detector at LEP. Lambda(b)'s are selected by the presence of energetic Lambda particles in bottom events tagged by the presence of displaced secondary vertices. A fit to the moments of the Lambda particles separates signal from B meson and fragmentation backgrounds. The measured product branching ratio isf(b --> Lambda(b)) . BR(Lambda(b) --> Lambda X) = (2.67) +/- 0.38(stat)(-0.60)(+0.67)(sys))%.Combined with a previous OPAL measurement, one obtainsf(b --> Lambda(b)) . BR(Lambda(b) --> Lambda X) = (3.50) +/- 0.32(stat) +/- 0.35(sys))%.