Title: Measurements of Cross Sections and Forward-Backward Asymmetries 
        at the Z Resonance and Determination of Electroweak Parameters


We report on measurements of hadronic and leptonic cross sections and 
leptonic forward-backward asymmetries performed with the L3 detector 
in the years 1993-95. A total luminosity of 103 pb-1 was collected at 
centre-of-mass energies around 91 GeV which corresponds to 2.5 million 
hadronic and 245 thousand leptonic events selected.
These data lead to a significantly improved determination of Z parameters.
From the total cross sections, combined with our measurements in 1990-92,
we obtain the final results for the mass and total withs of the Z as well 
as the partial witdhs into leptons and hadrons. From the invisible width 
we determine in the Standard Model the number of light neutrino species.
Adding our results on the leptonic forward-backward asymmetries and the
tau polarisation, the effective vector and axial-vector 
coupling constants of the neutral weak current to charged leptons 
are determined. Including our measurements of the Z -> b bbar forward-backward 
and quark charge asymmetries the effective electroweak mixing angle 
is derived. All these measurements are in good agreement with the 
Standard Model of electroweak interactions. Using all our measurements 
of electroweak observables an upper limit on the mass of the 
Standard Model Higgs boson of 133 GeV is set at 95% confidence level.


Parallel session #PA 5
Plenary session #Pl  6a 

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* paper 202 CERN-EP 2000-022, Eur.Jorn.Phys. C accepted *
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