Measurements of the $b \bar{b}$ production cross-section and forward backward asymmetry at center-of-mass energies above the $Z$ pole at LEP

The measurements of R b =σ( e + e − → b b ̄ )/σ( e + e − → q q ̄ ) and of the b quark forward–backward charge asymmetry, A fb b , at centre-of-mass energies above the Z pole are described. The measurement of R b is performed at s between 130 and 189 GeV using a b-tagging method that exploits the relatively large decay length of b-hadrons. The measurement of A fb b is performed using the large statistics event sample collected at s =189 GeV with a lepton-tag analysis based on the selection of prompt muons and electrons. The results at s =189 GeV are R b =0.163±0.013 (stat.) ±0.005 (syst.) , A fb b =0.61±0.18 (stat.) ±0.09 (syst.) .

electron positron: colliding beams
electron positron: annihilation
bottom: pair production
channel cross section: ratio
angular distribution: asymmetry
particle identification: bottom
decay: path length
lepton: momentum spectrum
lepton: transverse momentum
L3

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