A Measurement of the product branching ratio f(b ---> Lambda(b)) x BR(Lambda(b) ---> Lambda X) in Z0 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 are selected by the presence of energetic Lambda particles in bottom events tagged by the presence of displaced secondary vertices. A fit to the momenta of the Lambda particles separates signal from B meson and fragmentation backgrounds. The measured product branching ratio is f(b->Lambda_b).BR(Lambda_b->Lambda X) = (2.67+-0.38(stat)+0.67-0.60(sys))% Combined with a previous OPAL measurement, one obtains f(b->Lambda_b).BR(Lambda_b->Lambda X) = (3.50+-0.32(stat)+-0.35(sys))%.

electron positron: colliding beams
electron positron: annihilation
Z0: electroproduction
Z0: hadronic decay
bottom: pair production
bottom: fragmentation
Lambda/b0: decay modes
Lambda: hadronic decay
Lambda: momentum spectrum
transverse momentum: spectrum

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