Precise values of theZ resonance cross sections and lepton pair forward-backward asymmetries are measured from a sample of 1.3 millionZ 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 sgr h 0 =(41.60±0.16) nb, andR l =20.69±0.09. The corresponding number of light neutrino species isN v =2.983±0.034. The lepton pair forward-backward asymmetry is used to derive the ratio of vector to axial-vector couplings of leptons:g V 2 (M Z 2 )/g A 2 (M Z 2 )=0.0058 ±0.0011. An application of these results to constrain one model with extraZ bosons is presented.

Z production cross sections and lepton pair forward-backward asymmetries / D. Buskulic, D. Casper, I. Bonis, D. Decamp, P. Chez, C. Goy, J. -P. Lees, M. -N. Minard, P. Odier, B. Pietrzyk, F. Ariztizabal, P. Comas, J. M. Crespo, I. Efthymiopoulos, E. Fernandez, M. Fernandez-Bosman, V. Gaitan, Ll. Garrido, M. Martinez, T. Mattison, et al.. - In: ZEITSCHRIFT FÜR PHYSIK. C, PARTICLES AND FIELDS. - ISSN 0170-9739. - ELETTRONICO. - 62:(1994), pp. 539-550. [10.1007/BF01574159]

Z production cross sections and lepton pair forward-backward asymmetries

FOCARDI, ETTORE;CIULLI, VITALIANO;
1994

Abstract

Precise values of theZ resonance cross sections and lepton pair forward-backward asymmetries are measured from a sample of 1.3 millionZ 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 sgr h 0 =(41.60±0.16) nb, andR l =20.69±0.09. The corresponding number of light neutrino species isN v =2.983±0.034. The lepton pair forward-backward asymmetry is used to derive the ratio of vector to axial-vector couplings of leptons:g V 2 (M Z 2 )/g A 2 (M Z 2 )=0.0058 ±0.0011. An application of these results to constrain one model with extraZ bosons is presented.
1994
62
539
550
D. Buskulic;D. Casper;I. Bonis;D. Decamp;P. Chez;C. Goy;J. -P. Lees;M. -N. Minard;P. Odier;B. Pietrzyk;F. Ariztizabal;P. Comas;J. M. Cres...espandi
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/638341
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