UPDATED ANALYSIS OF HIGH-PRECISION LEP DATA

The precision electroweak data presented by the LEP Collaborations at La Thuile and Moriond Conferences in March 1993 are analyzed in a multiparameter framework that allows inclusion of a large category of extensions of the minimal SU(2)L x U(1) Standard Model. The main conclusions are: (i) The data agree well with the Minimal Standard Model (MSM); (ii) The best fit to the top quark and Higgs boson masses in the MSM is M(t) = 143 +/- 19/18 GeV, M(H) = 73 +/- 178/13 GeV. The positive error on M(H) is gaussian in log(M(H)). The data favor somewhat the lighter Higgs boson mass range but still agrees with M(H) = 1000 GeV within less than two standard deviations. (iii) The new results on GAMMA(b)/GAMMA(had) now play a fundamental role in deriving a DELTArho and M(H)-independent top quark mass limit from the Z --> bbBAR vertex correction. So far this limit was mostly obtained from R(had) and was intimately dependent on the value chosen for the strong coupling constant. With all data we find, for alpha(s) (M(Z)2) = 0.117 +/- 0.005, M(t) < 185 GeV at 95% CL, DELTArho and M(H) independent. As a consequence of this new precision on GAMMA(b)/GAMMA(had), it is possible to derive from electroweak measurements a value of alpha(s) (M(Z)2), even with all the electroweak parameters left free outside the MSM range: alpha(s) (M(Z)2) = 0.111 +/- 0.015.