Measurement of the Mass and Width of the Z0 Particle from Multi - Hadronic Final States Produced in e+ e- Annihilations

The DELPHI collaboration Aarnio, P. ; Abreu, P. ; Adam, W. ; et al.
Phys.Lett.B 231 (1989) 539-547, 1989.
Inspire Record 282905 DOI 10.17182/hepdata.29769

First measurements of the mass and width of the Z 0 performed at the newly commissioned LEP Collider by the DELPHI Collaboration are presented. The measuements are derived from the study of multihadronic final states produced in e + e − annihilations at several energies around the Z 0 mass. The values found for the mass and width are M (Z 0 )=91.06±0.09 (stat) ±0.045 (syst.) GeV and Γ (Z 0 )=2.42±0.21 (stat.) GeV respectively, froma three-parameter fit to the line shape. A two-parameter fit in the framework of the standard model yields for the number of light neutrino species N ν =2.4±0.4 (stat.) ±0.5 (syst.).

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Measurement of the e+ e- --> gamma gamma (gamma) cross section at the LEP energies.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 433 (1998) 429-440, 1998.
Inspire Record 472952 DOI 10.17182/hepdata.49434

The total and the differential cross-sections for the reaction e + e − → γγ ( γ ) have been measured with the DELPHI detector at LEP at centre-of-mass energies from 130 to 183 GeV for an integrated luminosity of 78.19 pb −1 . The results agree with the QED predictions. The lower limits (obtained including previously published results at the Z 0 energies) on the QED cutoff parameters are Λ + >253 GeV and Λ − >225 GeV and the lower bound on the mass of an excited electron with an effective coupling constant λ γ =1 is 231 GeV/ c 2 . All the limits are at the 95% confidence level.

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Measurement of the B(d)0 oscillation frequency using kaons, leptons and jet charge

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 72 (1996) 17-30, 1996.
Inspire Record 415900 DOI 10.17182/hepdata.47784

A measurement of the mass difference,Δm d , between the two physical B d

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THE REACTION ANTI-P P ---> DELTA (1236) ANTI-DELTA (1236) AT BEAM MOMENTA OF 7.23-GEV/C AND 12.0-GEV/C

Van Apeldoorn, G.W. ; Harting, D. ; Holthuizen, D.J. ; et al.
Z.Phys.C 12 (1982) 95-98, 1982.
Inspire Record 179937 DOI 10.17182/hepdata.16432

The reactionp→Δ(1236)\(\bar \Delta \)(1236) is studied at 7.23 GeV/c and at 12GeV/c in terms of the OPE model of Wolf. Good agreement between the model and experimental data is found for the mass andt distributions whereas for decay angular distributions the agreement is less satisfactory. A modified model, allowing for a spin orbit coupling, gives good agreement also for the angular distribution.

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The reaction e+ e- ---> gamma gamma (gamma) at Z0 energies

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Phys.Lett.B 268 (1991) 296-304, 1991.
Inspire Record 317825 DOI 10.17182/hepdata.29352

The total and differential cross-sections for the reaction e + e − → γγ ( γ ) are measured at centre of mass energies around 91 GeV using an integrated luminosity of 4.7 pb −1 . The aggreement with QED prediction is good. Consequently there is no evidence for non-standard channels which would have the same experimental signature. The lower limits on the QED cuttoff parameters are Λ + > 113 GeV and Λ − > 95 GeV. An upper limit on the effective coupling between a possible excited electron and the gamma is derived. At 95% confidence level the branching ratios for Z 0 decay into π 0 γ, ηψ and γγγ are below 1.5 × 10 −4 , 2.8 × 10 −4 and 1.4 × 10 −4 respectively.

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Measurement of the partial width of the decay of the Z0 into charm quark pairs

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Phys.Lett.B 252 (1990) 140-148, 1990.
Inspire Record 300162 DOI 10.17182/hepdata.48518

A determination of the partial width Γ c c ̄ of the Z 0 boson into charm quark pairs is presented, based on a total sample of 36 900 Z 0 hadronic decays measured with the DELPHI detector at the LEP collider. The production rate of cc̄ events is derived from the inclusive analysis of charged pions coming from the decay of charmed meson D ∗+ → D 0 π + and D ∗− → D ̄ 0 π − where the π ± is constrained by kinematics to have a low p T with respect to the axis. The probability to produce these π ± from D ∗± decay in cc̄ events is taken to be 0.31 ±_0.05 as measured at √ s =10.55 GeV. The measured relative partial width Γ c c ̄ Γ h = 0.162± 0.030 ( stat. ) ±0.050 ( syst. ) is in good agreement with the standard moel value of 0.171. Together with our previous measurement of the total hadronic width Γ h this implies Γ c c ̄ = 282±53 ( stat. )±88( syst. ) MeV .

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A Precise Measurement of the $Z$ Resonance Parameters Through Its Hadronic Decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Phys.Lett.B 241 (1990) 435-448, 1990.
Inspire Record 295501 DOI 10.17182/hepdata.29722

A measurement of the cross section for e + e - → hadrons using 11 000 hadronic decays of the Z boson at ten different center-of-mass energies is presented. A three-parameter fit gives the following values for the Z mass M z , the total width Γ z , the product of the electronic and hadronic partial widths Γ e Γ h , and the unfolded pole cross section σ 0 : M Z =91.171±0.030(stat)±0.030 (beam) GeV, Γ Z =2.511±0.065 GeV, Γ e Γ h =0.148±0.006 (stat.)±0.004 (syst.) GeV 2 , σ 0 =41.6±0.7(stat.)±1.1 (syst.) nb,

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Charged multiplicity and rapidity distributions in Z0 hadronic decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
CERN-PPE-90-117, 1990.
Inspire Record 299521 DOI 10.17182/hepdata.48523

None

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Energy-energy correlations in hadronic final states from Z0 decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Phys.Lett.B 252 (1990) 149-158, 1990.
Inspire Record 300161 DOI 10.17182/hepdata.29534

We have studied the energy-energy angular correlations in hadronic final states from Z 0 decay using the DELPHI detector at LEP. From a comparison with Monte Carlo calculations based on the exact second order QCD matrix element and string fragmentation we find that Λ (5) MS =104 +25 -20 ( stat. ) +25 -20( syst. ) +30 00 ) theor. ) . MeV, which corresponds to α s (91 GeV)=0.106±0.003(stat.)±0.003(syst.) +0.003 -0.000 (theor). The theoretical error stems from different choices for the renormalization scale of α s . In the Monte Carlo simulation the scale of α s as well as the fragmentation parameters have been optimized to described reasonably well all aspects of multihadron production.

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Study of Hadronic Decays of the $\Z^0$ Boson

The DELPHI collaboration Aarnio, P. ; Abreu, P. ; Adam, W. ; et al.
Phys.Lett.B 240 (1990) 271-282, 1990.
Inspire Record 294894 DOI 10.17182/hepdata.49562

Hadronic decays of Z 0 bosons are studied in the Delphi detector. Global event variables and singel particles inclusive distributions are compared with QCD-based predictions. The mean charged multiplicity is found to be 20.6±1.0 (stat+syst). The mean values of the sphericity, aplanarity, thrust, minor value, p in T and p out T are compared with values found at lower energy e + e − colliders.

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