A MEASUREMENT OF THE FORWARD-BACKWARD ASYMMETRY OF E(-)-]B(B)OVER-BARBY APPLYING A JET CHARGE ALGORITHM TO LIFETIME TAGGED EVENTS()E()

The forward-backward asymmetry of e(+)e(-) --> Z(0) --> b ($) over bar b has been measured using approximately 2.15 million hadronic Z(0) de cays collected at the LEP e+e(-) collider with the OPAL detector. A li fetime tag technique was used to select an enriched b ($) over bar b e vent sample. The measurement of the b ($) over bar b asymmetry was the n performed using a jet algorithm to determine the direction of the pr imary Values of: A(FB)(b) = 0.062 +/- 0.034 +/- 0.002 - 0.082 Delta(Ga mma (b ($) over bar b)/Gamma(had)) at root s = 89.52 GeV, A(FB)(b) = 0 .0963 +/- 0.0067 +/- 0.0038 - 0.471 Delta(Gamma(b ($) over bar b)/Gamm a(had) at root s = 91.25 GeV, A(FB)(b) = 0.172 +/- 0.0028 +/- 0.007 - 0.855 Delta(Gamma(b ($) over bar b)/Gamma(had)) at root s = 92.94 GeV, were measured where, in each case, the first error is statistical, th e second is systematic and the third term gives the variation due to a change Delta(Gamma(b ($) over bar b) /Gamma(had)) in the value of Gam ma(b ($) over bar b)/Gamma(had) = 0.216 assumed. The dependence on the assumed charm asymmetry at the same energy is Delta(A(FB)(b))approxim ate to+0.07 Delta(A(FB)(c)). Assuming the Standard Model form for the couplings, these measurements correspond to an effective weak mixing a ngle of: sin(2) theta(W)(eff,e) = 0.2313 +/- 0.0012 +/- 0.0006 giving M(top) = 196(-38-19)(+33+16) GeV/c(2) where the first error is statist ical and the second is systematic. The Higgs mass assumed is 300 GeV/c (2). A variation in the assumed mass of the Higgs boson between 60 and 1000 GeV/c(2) corresponds to an uncertainty in sin(2) theta(W)(eff,e) of +/- 0.00006 and on M(top) of(-26)(+20) GeV/c(2).