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Properties of Hadronic Events in e$^{+} $e$^{-}$ Annihilation at $S^{(1/2)}=91$-{GeV}

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Lees, J.P. ; et al.

Phys.Lett.B 234 (1990) 209-218, 1990.

Inspire Record 283354 DOI 10.17182/hepdata.29739

We report on properties of hadronic events from e + e − annihilation observed by the ALEPH detector at the large Electron Positron Collider at CERN. The center-of-mass energy was s =91.0−91.3 GeV . Measured distributions of the global event-shape variables sphericity, aplanarity, thrust and minor value, and of the inclusive variables x p , p ⊥ in , p ⊥ out and y are presented. We measure a mean charged multiplicity in hadronic events of 〈 N ch 〉=21.3±0.1 (statistical)±0.6 (systematic). The data are in good agreement with QCD-based models which use the leading-logarithm approximation, and are less well described by a model using O( α s 2 ) QCD.

1 data table

Table 1

NO RAD. CORR APPLIED.

Measurement of the Z0 Mass and Width with the OPAL Detector at LEP

The OPAL collaboration Akrawy, M.Z. ; Alexander, G. ; Allison, J. ; et al.

Phys.Lett.B 231 (1989) 530-538, 1989.

Inspire Record 282821 DOI 10.17182/hepdata.29757

We report an experimental determination of the cross section for e + e − → hadrons from a scan around the Z 0 pole. On the basis of 4350 hadronic events collected over seven energy points between 89.26 GeV and 93.26 GeV we obtain a mass of m z =91.01±0.05±0.05 GeV, and a total decay width of Γ z =2.60±0.13 GeV. In the context of the standard model t these results imply 3.1 ± 0.4 neutrino generations.

1 data table

Table 1

No description provided.

Determination of the Number of Light Neutrino Species

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Lees, J.P. ; et al.

Phys.Lett.B 231 (1989) 519-529, 1989.

Inspire Record 282904 DOI 10.17182/hepdata.29758

The cross-section for e + e − → hadrons in the vicinity of the Z boson peak has been measured with the ALEPH detector at the CERN Large Electron Positron collider, LEP. Measurements of the Z mass, M z = (91.174±0.070) GeV, the Z width Γ z =(2.68±0.15) GeV, and of the peak hadronic cross-section, σ had peak =(29.3±1.2) nb, are presented. With the constraints of the standard electroweak model, the number of light neutrino species is found to be N v =3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL.

2 data tables

Table 1

Selection from TPC tracks.

Table 2

Selection by calorimeters.

A Determination of the Properties of the Neutral Intermediate Vector Boson Z0

The L3 collaboration Adeva, B. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.

Phys.Lett.B 231 (1989) 509, 1989.

Inspire Record 282041 DOI 10.17182/hepdata.29768

We report the results of first physics runs of the L3 detector at LEP. Based on 2538 hadron events, we determined the mass m z 0 and the width Γ z 0 of the intermediate vector boson Z 0 to be m z 0 =91.132±0.057 GeV (not including the 46 MeV LEP machine energy uncertainty) and Γ z 0 =2.588±0.137 GeV. We also determined Γ invisible =0.567±0.080 GeV, corresponding to 3.42±0.48 number of neutrino flavors. We also measured the muon pair cross section and determined the branching ratio Γ μμ = Γ h =0.056±0.006. The partial width of Z 0 →e + e − is Γ ee =88±9±7 MeV.

1 data table

Table 1

No description provided.