Measurements of the bb̄ production cross section and forward-backward asymmetry at centre-of-mass energies above the Z pole at LEP

The measurements of R(b) = σ(e⁺e^- → bb̄)/σ(e⁺e^- → qq̄) 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.).