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ALEXANDER 1991C

OPAL collaboration; Alexander, G. et al.
Measurement of the Z^o Line Shape Parameters and the Electroweak Couplings of Charged Leptons
Z. Phys. C52 (1991) 175;

Abstracts
We report on an improved measurement of the mass of the Z^o boson, its total width and its partial decay width into hadrons and leptons, as well as the effective axial vector and vector couplings to charged leptons. These measurements are based on a data set of approximately 160000 hadronic Z^o decays and 18000 decays into electrons, muons and taus, recorded by the OPAL experiment at centre of mass energies near the mass of Z^o. The total width and the partial width to visible final states, derived from the measured cross sections, are used to extract the invisible width. The effective couplings of the Z^o to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at the different centre of mass energy points of the Z^o scan. The implications of our results in the context of the Standard Model are discussed.

Accelerator CERN-LEP Detectors OPAL

Related references
More (earlier) information appears in
OPAL Coll., M. Z. Akrawy et al., Phys. Lett. 247B (1990) 458;
OPAL Coll., M. Z. Akrawy et al., Phys. Lett. 240B (1990) 497;

Reactions

	e+ e– 2hadron (hadrons)	88.233-95.036 GeV (Ecm)	cs, angp, const
	e+ e– e– e+	88.233-95.036 GeV (Ecm)	cs, angp, const
	e+ e– μ– μ+	88.233-95.036 GeV (Ecm)	cs, angp, const
	e+ e– τ– τ+	88.233-95.036 GeV (Ecm)	cs, angp, const
	e+ e– e– e+ 2jet	88.233-95.036 GeV (Ecm)	cs, angp, const
	e+ e– μ– μ+ 2jet	88.233-95.036 GeV (Ecm)	cs, angp, const
	Zo e– e+
	Zo μ– μ+
	Zo τ– τ+
	Zo 2hadron (hadrons)

Particles studied

	Zo	mass, w, pw
	ν	ex

Record comments
Confirmation of the number of light neutrinos = 3. OPAL Collaboration.

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