Precise determination of the Z resonance parameters at LEP: 'Zedometry'.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 19 (2001) 587-651, 2001.
Inspire Record 538108 DOI 10.17182/hepdata.49855

This final analysis of hadronic and leptonic cross-sections and of leptonic forward-backward asymmetries in e+e- collisions with the OPAL detector makes use of the full LEP1 data sample comprising 161 pb^-1 of integrated luminosity and 4.5 x 10^6 selected Z decays. An interpretation of the data in terms of contributions from pure Z exchange and from Z-gamma interference allows the parameters of the Z resonance to be determined in a model-independent way. Our results are in good agreement with lepton universality and consistent with the vector and axial-vector couplings predicted in the Standard Model. A fit to the complete dataset yields the fundamental Z resonance parameters: mZ = 91.1852 +- 0.0030 GeV, GZ = 2.4948 +- 0.0041 GeV, s0h = 41.501 +- 0.055 nb, Rl = 20.823 +- 0.044, and Afb0l = 0.0145 +- 0.0017. Transforming these parameters gives a measurement of the ratio between the decay width into invisible particles and the width to a single species of charged lepton, Ginv/Gl = 5.942 +- 0.027. Attributing the entire invisible width to neutrino decays and assuming the Standard Model couplings for neutrinos, this translates into a measurement of the effective number of light neutrino species, N_nu = 2.984 +- 0.013. Interpreting the data within the context of the Standard Model allows the mass of the top quark, mt = 162 +29-16 GeV, to be determined through its influence on radiative corrections. Alternatively, utilising the direct external measurement of mt as an additional constraint leads to a measurement of the strong coupling constant and the mass of the Higgs boson: alfa_s(mZ) = 0.127 +- 0.005 and mH = 390 +750-280 GeV.

3 data tables match query

The forward-backward charge asymmetry in E+ E- --> MU+ MU- production corrected to the simple kinematic acceptance region ABS(COS(THETA(P=5))) < 0.95 and THETA(C=ACOL) < 15 degrees, and the energy of each fermion required to be greaterthan 6 GeV. Statistical errors only are shown. Also given are the asymmetries a fter correction for the beam energy spread to correspond to the physical asymmetry at the central value of SQRT(S).

The forward-backward charge asymmetry in E+ E- --> TAU+ TAU- production corrected to the simple kinematic acceptance region ABS(COS(THETA(P=5))) < 0.90 andTHETA(C=ACOL) < 15 degrees, and the energy of each fermion required to be great er than 6 GeV. Statistical errors only are shown. Also given are the asymmetriesafter correction for the beam energy spread to correspond to the physical asymm etry at the central value of SQRT(S).

The forward-backward charge asymmetry in E+ E- --> E+ E- production corrected to the simple kinematic acceptance region ABS(COS(THETA(P=5))) < 0.70 and THETA(C=ACOL) < 10 degrees, and the energy of each fermion required to be greater than 6 GeV. Statistical errors only are shown. Also given are the asymmetries after correction for the beam energy spread to correspond to the physical asymmetryat the central value of SQRT(S).


A MEASUREMENT OF e+ e- ---> b anti-b FORWARD - BACKWARD CHARGE ASYMMETRY BETWEEN s**(1/2) = 52-GeV AND 57-GeV

The AMY collaboration Sagawa, H. ; Lim, J. ; Abe, K. ; et al.
Phys.Rev.Lett. 63 (1989) 2341, 1989.
Inspire Record 279824 DOI 10.17182/hepdata.19996

Using 123 multihadronic inclusive muon-production e+e− annihilation events at an average c.m. energy of 55.2 GeV, we extracted the forward-backward charge asymmetry of the e+e−→bb¯ process and the R ratio for bb¯ production. We used an analysis method in which the behavior of the c quark and lighter quarks is assumed, with only that of the b quark left indeterminate. The results, Ab=-0.72±0.28(stat)±0.13(syst) and Rb=0.57±0.16±0.10, are consistent with the standard model.

1 data table match query

Asymmetry in BOTTOM quark production.


Analysis of Z0 couplings to charged leptons

The OPAL collaboration Akrawy, M.Z. ; Alexander, G. ; Allison, J. ; et al.
Phys.Lett.B 247 (1990) 458-472, 1990.
Inspire Record 297139 DOI 10.17182/hepdata.29630

The couplings of the Z 0 to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at centre of mass energies near to the mass of the Z 0 . The data are consistent with lepton universality. Using a parametrisation of the lepton pair differential cross section which assumes that the Z 0 has only vector and axial couplings to leptons, the charged leptonic partial decay width of the Z 0 is determined to be Г ol+ol− = 83.1±1.9 MeV and the square of the product of the effective axial vector and vector coupling constants of the Z 0 to charged leptons to be a ̌ 2 ol v ̌ 2 ol = 0.0039± 0.0083 , in agreement with the standard model. A parametrisation in the form of the improved Born approximation gives effective leptonic axial vector and vector coupling constants a ̌ 2 ol = 0.998±0.024 and v ̌ 2 ol = 0.0044±0.0083 . In the framework of the standard model, the values of the parameters ϱ z and sin 2 θ w are found to be 0.998±0.024 and 0.233 +0.045 −0.012 respectively. Using the relationship in the minimal standard model between ϱ z and sin 2 θ w , the results sin 2 θ SM w = 0.233 +0.007 −0.006 is obtained. Our previously published measurement of the ratio of the hadronic to the leptonic partial width of the Z 0 is update: R z = 21.72 +0.71 −0.65 .

3 data tables match query

Forward-backward asymmetry corrected for kinematic cuts. Errors have systematics folded.

Forward-backward asymmetry. Statistical errors only.

Forward-backward asymmetry. Statistical errors only.


Final Results on $\mu$ and Tau Pair Production by the Jade Collaboration at {PETRA}

The JADE collaboration Hegner, S. ; Naroska, B. ; Schroth, F. ; et al.
Z.Phys.C 46 (1990) 547-554, 1990.
Inspire Record 284560 DOI 10.17182/hepdata.15279

The cross-sections and the forward-backward charge asymmetries of muon and tau pairs produced ine+e− collisions at\(\sqrt s= 35 GeV\) have been measured by the JADE Collaboration. The cross-sections,\(\sigma _\mu(\sqrt s= GeV) = 69.79 \pm 1.35 \pm 1.40 pb\) and\(\sigma _\mu(\sqrt s= GeV) = 71.72 \pm 1.48 \pm 1.61 pb\), are in agreement with the QED α3 prediction. The charge asymmetries areAμ=−(9.9±1.5±0.5)% andAτ=−(8.1±2.0±0.6)% in agreement with the value −9.2% predicted by the standard model, usingMZ=91.0 GeV and sin2θW=0.230.

1 data table match query

No description provided.


Measurement of muon pair production at 50-GeV < s**(1/2) < 86-GeV at LEP

The L3 collaboration Acciarri, M. ; Adam, A. ; Adriani, O. ; et al.
Phys.Lett.B 374 (1996) 331-340, 1996.
Inspire Record 416744 DOI 10.17182/hepdata.47586

Using the data recorded with the L3 detector at LEP, we study the process e + e − → μ + μ − ( γ ) for events with hard initial-state photon radiation. The effective centre-of-mass energies of the muons range from 50 GeV to 86 GeV. The data sample corresponds to an integrated luminosity of 103.5 pb −1 and yields 293 muon-pair events with a hard photon along the beam direction. The events are used to determine the cross sections and the forward-backward charge asymmetries at centre-of-mass energies below the Z resonance.

2 data tables match query

Forward-Backward Asymmetry from fit as function of the reduced centre-of-mass energy.

Background corrected Forward-Backward Asymmetry as function of the reduced centre-of-mass energy.


Study of the muon pair production at center-of-mass energies from 20-GeV to 136-GeV with the ALEPH detector

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Phys.Lett.B 399 (1997) 329-341, 1997.
Inspire Record 440218 DOI 10.17182/hepdata.47490

The total cross section and the forward-backward asymmetry for the process e + e − → μ + μ − ( nγ ) are measured in the energy range 20–136 GeV by reconstructing the effective centre-of-mass energy after initial state radiation. The analysis is based on the data recorded with the ALEPH detector at LEP between 1990 and 1995, corresponding to a total integrated luminosity of 143.5 pb −1 . Two different approaches are used: in the first one an exclusive selection of events with hard initial state radiation in the energy range 20–88 GeV is directly compared with the Standard Model predictions showing good agreement. In the second one, all events are used to obtain a precise measurement of the energy dependence of σ 0 and A FB 0 from a model independent fit, enabling constraints to be placed on models with extra Z bosons.

2 data tables match query

Exlclusive analysis from events with hard ISR.

Inclusive analysis from evvents with no specific selection of hard ISR.


Measurement of hadron and lepton pair production from e+ e- annihilation at center-of-mass energies of 130-GeV and 136-GeV

The ALEPH collaboration Buskulic, D. ; De Bonis, I. ; Decamp, D. ; et al.
Phys.Lett.B 378 (1996) 373-384, 1996.
Inspire Record 421552 DOI 10.17182/hepdata.47801

Hadronic and leptonic cross-sections and forward-backward asymmetries are measured using 5.7 pb −1 of data taken with the ALEPH detector at LEP at centre-of-mass energies of 130 and 136 GeV. The results agree with Standard Model expectations. The measurement of hadronic cross-sections far away from the Z resonance improves the determination of the interference between photon and Z exchange. Constraints on models with extra Z bosons are presented.

5 data tables match query

Forward-Backward Asymmetry with loose SPRIME cuts.

Forward-Backward Asymmetry with tight SPRIME cuts.

Forward-Backward Asymmetry with loose SPRIME cuts.

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DELPHI results on the Z0 resonance parameters through its hadronic and leptonic decay modes

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
CERN-PPE-90-119, 1990.
Inspire Record 298840 DOI 10.17182/hepdata.47313

None

2 data tables match query

Asymmetries. Systematic error is 1 pct.

Asymmetries. Systematic error is 1 pct.


Search for a Z-prime at the Z resonance

The L3 collaboration Adriani, O. ; Aguilar-Benitez, M. ; Ahlen, S.P. ; et al.
Phys.Lett.B 306 (1993) 187-196, 1993.
Inspire Record 355489 DOI 10.17182/hepdata.28919

The search for an additional heavy gauge boson Z′ is described. The models considered are based on either a superstring-motivated E 6 or on a left-right symmetry and assume a minimal Higgs sector. Cross sections and asymmetries measured with the L3 detector in the vicinity of the Z resonance during the 1990 and 1991 running periods are used to determine limits on the Z-Z′ gauge boson mixing angle and on the Z′ mass. For Z′ masses above the direct limits, we obtain the following allowed ranges of the mixing angle, θ M at the 95% confidence level: −0.004 ⪕ θ M ⪕ 0.015 for the χ model, −0.003 ⪕ θ M ⪕ 0.020 for the ψ model, −0.029 ⪕ θ M ⪕ 0.010 for the η model, −0.002 ⪕ θ M ⪕ 0.020 for the LR model,

2 data tables match query

Data taken during 1990.

Data taken during 1991.


Cross-sections and leptonic forward-backward asymmetries from the Z0 running of LEP.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 16 (2000) 371-405, 2000.
Inspire Record 527605 DOI 10.17182/hepdata.49969

During 1993 and 1995 LEP was run at 3 energies near the Z$^0$peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP o

10 data tables match query

Cross section and forward-backward asymmetry in the E+ E- channel for the 1993 data. The polar angle is 44 to 136 degrees. Additional systematic error for cross section of 0.46 PCT (efficiencies and backgrounds) and 0.29 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0026.

Cross section and forward-backward asymmetry in the E+ E- channel for the 1994 data. The polar angle is 44 to 136 degrees. Additional systematic error for cross section of 0.52 PCT (efficiencies and backgrounds) and 0.14 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0021.

Cross section and forward-backward asymmetry in the E+ E- channel for the 1995 data. The polar angle is 44 to 136 degrees. Additional systematic error for cross section of 0.52 PCT (efficiencies and backgrounds) and 0.14 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0020.

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