A Measurement of R(b) using a lifetime mass tag

ALEPH's published measurement of R b = Γ( Z → b b ) Γ( Z → hadrons ) using a lifetime tag is updated using the full LEP 1 data sample. Considerable effort has been devoted to understanding systematic effects. Charm background is better controlled by combining the lifetime tag with a tag based on the b c hadron mass difference. Furthermore, the algorithm used to reconstruct the event primary vertex is designed so as to reduce correlations between the two hemispheres of an event. The value of R b is measured to be 0.2167 ± 0.0011(stat) ± 0.0013(syst).

electron positron: colliding beams
electron positron: annihilation
Z0: electroproduction
Z0: hadronic decay
Z0: branching ratio
bottom: pair production
particle identification: flavor
efficiency
hadron: mass difference
angular correlation: correction

References(11)

Figures(0)

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