DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS
From measurements of the cross sections for e+e-→ hadrons and the cross sections and forward-backward charge-asymmetries for ee-→e+e-, μ+μ- and π+π- at several centre-of-mass energies around the Z0 pole with the DELPHI apparatus, using approximately 150 000 hadronic and leptonic events from 1989 and...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Journal article |
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1991
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| _version_ | 1797094216439955456 |
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| author | Abreu, P Adam, W Adami, F Adye, T Akesson, T Alekseev, G Allen, P Almehed, S Alted, F Alvsvaag, S Amaldi, U Anassontzis, E Antilogus, P Apel, W Apsimon, R Asman, B Astier, P Augustin, J Augustinus, A Baillon, P Bambade, P Barao, F Barbiellini, G Bardin, D Baroncelli, A |
| author_facet | Abreu, P Adam, W Adami, F Adye, T Akesson, T Alekseev, G Allen, P Almehed, S Alted, F Alvsvaag, S Amaldi, U Anassontzis, E Antilogus, P Apel, W Apsimon, R Asman, B Astier, P Augustin, J Augustinus, A Baillon, P Bambade, P Barao, F Barbiellini, G Bardin, D Baroncelli, A |
| author_sort | Abreu, P |
| collection | OXFORD |
| description | From measurements of the cross sections for e+e-→ hadrons and the cross sections and forward-backward charge-asymmetries for ee-→e+e-, μ+μ- and π+π- at several centre-of-mass energies around the Z0 pole with the DELPHI apparatus, using approximately 150 000 hadronic and leptonic events from 1989 and 1990, one determines the following Z0 parameters: the mass and total width MZ = 91.177 ± 0.022 GeV, ΓZ = 2.465 ± 0.020 GeV, the hadronic and leptonic partial widths Γh = 1.726 ± 0.019 GeV, Γl = 83.4 ± 0.8 MeV, the invisible width Γinv = 488 ± 17 MeV, the ratio of hadronic over leptonic partial widths RZ = 20.70 ± 0.29 and the Born level hadronic peak cross section σ0 = 41.84±0.45 nb. A flavour-independent measurement of the leptonic cross section gives very consistent results to those presented above (Γl = 83.7 ± 0.8rmMeV). From these results the number of light neutrino species is determined to be Nv = 2.94 ±0.10. The individual leptonic widths obtained are: Γe = 82.4±_1.2 MeV, Γu = 86.9±2.1 MeV and Γτ = 82.7 ± 2.4 MeV. Assuming universality, the squared vector and axial-vector couplings of the Z0 to charged leptons are: V ̄l 2 = 0.0003±0.0010 and A ̄l 2 = 0.2508±0.0027. These values correspond to the electroweak parameters: ρ{variant}eff = 1.003 ± 0.011 and sin2θW eff = 0.241 ± 0.009. Within the Minimal Standard Model (MSM), the results can be expressed in terms of a single parameter: sin2θW M ̄S = 0.2338 ± 0.0027. All these values are in good agreement with the predictions of the MSM. Fits yield 43 |
| first_indexed | 2024-03-07T04:11:00Z |
| format | Journal article |
| id | oxford-uuid:c7cdf767-25db-4dbb-8601-960017e734c3 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T04:11:00Z |
| publishDate | 1991 |
| record_format | dspace |
| spelling | oxford-uuid:c7cdf767-25db-4dbb-8601-960017e734c32022-03-27T06:47:57ZDETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYSJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:c7cdf767-25db-4dbb-8601-960017e734c3Symplectic Elements at Oxford1991Abreu, PAdam, WAdami, FAdye, TAkesson, TAlekseev, GAllen, PAlmehed, SAlted, FAlvsvaag, SAmaldi, UAnassontzis, EAntilogus, PApel, WApsimon, RAsman, BAstier, PAugustin, JAugustinus, ABaillon, PBambade, PBarao, FBarbiellini, GBardin, DBaroncelli, AFrom measurements of the cross sections for e+e-→ hadrons and the cross sections and forward-backward charge-asymmetries for ee-→e+e-, μ+μ- and π+π- at several centre-of-mass energies around the Z0 pole with the DELPHI apparatus, using approximately 150 000 hadronic and leptonic events from 1989 and 1990, one determines the following Z0 parameters: the mass and total width MZ = 91.177 ± 0.022 GeV, ΓZ = 2.465 ± 0.020 GeV, the hadronic and leptonic partial widths Γh = 1.726 ± 0.019 GeV, Γl = 83.4 ± 0.8 MeV, the invisible width Γinv = 488 ± 17 MeV, the ratio of hadronic over leptonic partial widths RZ = 20.70 ± 0.29 and the Born level hadronic peak cross section σ0 = 41.84±0.45 nb. A flavour-independent measurement of the leptonic cross section gives very consistent results to those presented above (Γl = 83.7 ± 0.8rmMeV). From these results the number of light neutrino species is determined to be Nv = 2.94 ±0.10. The individual leptonic widths obtained are: Γe = 82.4±_1.2 MeV, Γu = 86.9±2.1 MeV and Γτ = 82.7 ± 2.4 MeV. Assuming universality, the squared vector and axial-vector couplings of the Z0 to charged leptons are: V ̄l 2 = 0.0003±0.0010 and A ̄l 2 = 0.2508±0.0027. These values correspond to the electroweak parameters: ρ{variant}eff = 1.003 ± 0.011 and sin2θW eff = 0.241 ± 0.009. Within the Minimal Standard Model (MSM), the results can be expressed in terms of a single parameter: sin2θW M ̄S = 0.2338 ± 0.0027. All these values are in good agreement with the predictions of the MSM. Fits yield 43 |
| spellingShingle | Abreu, P Adam, W Adami, F Adye, T Akesson, T Alekseev, G Allen, P Almehed, S Alted, F Alvsvaag, S Amaldi, U Anassontzis, E Antilogus, P Apel, W Apsimon, R Asman, B Astier, P Augustin, J Augustinus, A Baillon, P Bambade, P Barao, F Barbiellini, G Bardin, D Baroncelli, A DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS |
| title | DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS |
| title_full | DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS |
| title_fullStr | DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS |
| title_full_unstemmed | DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS |
| title_short | DETERMINATION OF Z0 RESONANCE PARAMETERS AND COUPLINGS FROM ITS HADRONIC AND LEPTONIC DECAYS |
| title_sort | determination of z0 resonance parameters and couplings from its hadronic and leptonic decays |
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