Precise values of the Z resonance cross sections and lepton pair forward-backward asymmetries are measured from a sample of 1.3 million Z decays into hadrons and charged leptons taken with the ALEPH detector at LEP. A silicon-tungsten luminosity calorimeter was installed in ALEPH in 1992, permitting the determination of the absolute luminosity to a systematic precision of 0.15% (experimental) and 0.25% (theoretical). This is combined with a better understanding of the hadronic event selection and an improved tau pair selection. Including the ALEPH results of the past three years one obtains σh 0 =(41.60±0.16) nb, and Rl=20.69±0.09. The corresponding number of light neutrino species is Nv =2.983±0.034. The lepton pair forward-backward asymmetry is used to derive the ratio of vector to axial-vector couplings of leptons:gV 2(MZ 2)/gA 2(MZ 2)=0.0058 ±0.0011. An application of these results to constrain one model with extra Z bosons is presented.

Buskulic, D., Casper, D., Debonis, I., Decamp, D., Ghez, P., Goy, C., et al. (1994). Z production cross sections and lepton pair forward-backward asymmetries. ZEITSCHRIFT FÜR PHYSIK. C, PARTICLES AND FIELDS, 62(4), 539-550 [10.1007/BF01574159].

Z production cross sections and lepton pair forward-backward asymmetries

CARPINELLI, Massimo;
1994

Abstract

Precise values of the Z resonance cross sections and lepton pair forward-backward asymmetries are measured from a sample of 1.3 million Z decays into hadrons and charged leptons taken with the ALEPH detector at LEP. A silicon-tungsten luminosity calorimeter was installed in ALEPH in 1992, permitting the determination of the absolute luminosity to a systematic precision of 0.15% (experimental) and 0.25% (theoretical). This is combined with a better understanding of the hadronic event selection and an improved tau pair selection. Including the ALEPH results of the past three years one obtains σh 0 =(41.60±0.16) nb, and Rl=20.69±0.09. The corresponding number of light neutrino species is Nv =2.983±0.034. The lepton pair forward-backward asymmetry is used to derive the ratio of vector to axial-vector couplings of leptons:gV 2(MZ 2)/gA 2(MZ 2)=0.0058 ±0.0011. An application of these results to constrain one model with extra Z bosons is presented.
Articolo in rivista - Articolo scientifico
Physics
English
539
550
12
Buskulic, D., Casper, D., Debonis, I., Decamp, D., Ghez, P., Goy, C., et al. (1994). Z production cross sections and lepton pair forward-backward asymmetries. ZEITSCHRIFT FÜR PHYSIK. C, PARTICLES AND FIELDS, 62(4), 539-550 [10.1007/BF01574159].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/390401
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