Precision measurements of the neutral current from hadron and lepton production at LEP

The OPAL collaboration Acton, P.D. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 58 (1993) 219-238, 1993.
Inspire Record 352696 DOI 10.17182/hepdata.14495

New measurements of the hadronic and leptonic cross sections and of the leptonic forward-backward asymmetries ine+e− collisions are presented. The analysis includes data recorded up to the end of 1991 by the OPAL experiment at LEP, with centre-of-mass energies within ±3 GeV of the Z0 mass. The results are based on a recorded total of 454 000 hadronic and 58 000 leptonic events. A model independent analysis of Z0 parameters based on an extension of the improved Born approximation is presented leading to test of lepton universality and an interpretation of the results within the Standard Model framework. The determination of the mass and width of the Z0 benefit from an improved understanding of the LEP energy calibration.

5 data tables match query

Additional systematic error of 0.003.

Forward-backward asymmetry from counting number of events. Additional systematic error of 0.003.

Forward-backward asymmetry from maximum likelihood fit to cos(theta) distribution. Additional systematic error of 0.003.

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Measurement of the Z0 line shape parameters and the electroweak couplings of charged leptons

The OPAL collaboration Alexander, G. ; Allison, John ; Allport, P.P. ; et al.
Z.Phys.C 52 (1991) 175-208, 1991.
Inspire Record 315269 DOI 10.17182/hepdata.14859

None

3 data tables match query

Forward-backward asymmetry calculated from number of events from combined 1989 and 1990 data.

Forward-backward asymmetry resulted from a maximum-likelihood fit to the COS(THETA) distribution from combined 1989 and 1990 data.

Forward-backward asymmetry resulted from a maximum-likelihood fit to the COS(THETA) distribution from combined 1989 and 1990 data.


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.


Experimental limits on extra Z bosons from e+ e- annihilation data with the VENUS detector at s**(1/2) = 50-GeV to approximately 64-GeV

The VENUS collaboration Abe, K. ; Amako, K. ; Arai, Y. ; et al.
Phys.Lett.B 246 (1990) 297-305, 1990.
Inspire Record 296392 DOI 10.17182/hepdata.29664

We have tested extra Z models in the reactions e + e − → μ + μ − , τ + τ − and hadrons in the energy range 50< s <64 GeV using the VENUS detector at the TRISTAN e + e − storage ring. Our data are in good agreement with the standard model prediction ( χ 2 N Df = 2.9 31 ) ). We have obtained 90% confidence-level lower limits of 105, 125 and 231 GeV for the masses of Z Ψ , Z η and Z χ bosons which are expected from the E 6 grand unified theory. We also place a 90% confidence-level lower limit of 426 GeV for the mass of an extra-Z boson whose couplings to quarks and leptons are assumed to be the same as those for the standard Z boson. Our results exceed the previous experimental limits from the p p collider experiments, although there have been some combined analyses reporting the limits better than those obtained in the present analysis.

3 data tables match query

New measurements. Statistical and systematic errors combined in quadrature.

New measurements.

Combination of selected VENUS data from this and previous publications. Statistical and systematic errors combined in quadrature.


Charge Asymmetry of Hadron Jets and Limits on the Compositeness Scales in e$^{+} $e$^{-} \To $q$ \Bar{$q$}$ Reaction at $\Sqrt{$s$}=57$.6-{GeV}

The VENUS collaboration Abe, K. ; Amako, K. ; Arai, Y. ; et al.
Phys.Lett.B 232 (1989) 425-430, 1989.
Inspire Record 281245 DOI 10.17182/hepdata.29751

A charge asymmetry has been measured in hadron jets from e + e − annihilation at energies between 52 and 61.4 geV (〈√ s 〉=57.6 GeV). The measured asymmetry is A =11.4%±2.2%±2.1% and is consistent with the prediction of the standard model of the electroweak theory. By using the differential cross section, lower limits of the compositeness scale in eeqq contact interactions have been determined to be typically a few TeV at 95% CL.

1 data table match query

Data are fully corrected for detector effects, resolution and radiative effects.


Measurement and interpretation of fermion pair production at LEP energies from 130-GeV to 172-GeV

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 11 (1999) 383-407, 1999.
Inspire Record 495462 DOI 10.17182/hepdata.34520

None

4 data tables match query

No description provided.

No description provided.

No description provided.

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Asymmetry in the Angular Distribution of Inclusive $\Lambda$ Baryons From $e^+ e^-$ Annihilations at $\sqrt{s}=29$-{GeV}

Abachi, S. ; Baringer, Philip S. ; Bylsma, B.G. ; et al.
Phys.Lett.B 181 (1986) 403-406, 1986.
Inspire Record 18955 DOI 10.17182/hepdata.30215

A forward-backward asymmetry A , consistent with that expected from the γ − Z 0 interference term in the process e + e − → q q , is observed in the laboratory production angular distribution of high-momentum ∧ baryons. The data were collected with the High Resolution Spectrometer at PEP. The asymmetry for ∧ baryons with fractional energy z= 2E s greater than 0.3 is A = (−23± 8 plusmn ; 2)%.

2 data tables match query

No description provided.

Data read from graph.


Peripheral Dipion Production by Pions of 12 and 18 GeV/c

Jones, Lawrence W. ; Bleuler, E. ; Caldwell, D.O. ; et al.
Phys.Rev. 166 (1968) 1405-1430, 1968.
Inspire Record 944942 DOI 10.17182/hepdata.26526

A spark-chamber experiment on the peripheral production of 9245 pion pairs by 12- and 18-GeV/c incident pions is reported and analyzed in terms of a one-pion-exchange model in which the final state at the nucleon vertex contains generally one or more pions. The relevant dynamics and kinematics appropriate to this problem are reviewed, and the experimental and analysis techniques giving good resolution and detection-bias correction are discussed in some detail. From the results, fair agreement is found between the data and the one-pion-exchange calculation of the ρ0 production cross sections and of the associated missing-mass spectra. The ρ0 is found to be consistent with a single peak, and no evidence of peak splitting is observed. A search for a narrow s-wave dipion resonance is made with negative results. Normalizing to the ρ0 meson, the s-wave π+π− scattering cross section is computed from the abundant low-dipion-mass events, giving a cross section falling smoothly from 50 mb (300 MeV) to about 20 mb (600 MeV). No evidence of an s-wave resonance is found in this range of energies. Below 450 MeV, the pion-pion scattering asymmetry favors backward scattering (by 2½ standard deviations), which is consistent with a negative and falling J=T=0 phase shift. The extrapolated forward-backward asymmetry and the s-wave cross section are both consistent with a J=T=0 phase shift near|90°| at about 750 MeV.

3 data tables match query

Forward-backward asymmetry for the dipion production under RHO resonance. Asymmetry defined as P = (F-B)/(F+B), where F corresponds to dipion eventswith THETA > 90 deg, B corresponds to dipion events with THETA < 90 deg, and TH ETA is the polar angle between the incident and the scattered negative pion in the dipion center-of-mass system.

Forward-backward asymmetry for the dipion production under RHO resonance. Asymmetry defined as P = (F-B)/(F+B), where F corresponds to dipion eventswith THETA > 90 deg, B corresponds to dipion events with THETA < 90 deg, and TH ETA is the polar angle between the incident and the scattered negative pion in the dipion center-of-mass system.

Forward-backward asymmetry for the dipion production under RHO resonance. Asymmetry defined as P = (F-B)/(F+B), where F corresponds to dipion eventswith THETA > 90 deg, B corresponds to dipion events with THETA < 90 deg, and TH ETA is the polar angle between the incident and the scattered negative pion in the dipion center-of-mass system. 12 and 18 GeV averaged.


Study of the $e^+ e^-\to\mu^+ \mu^- \gamma$ reaction at center-of-mass energies between 54 and 64 GeV

The VENUS collaboration Yonezawa, Y. ; Abe, K. ; Amako, K. ; et al.
Phys.Lett.B 264 (1991) 212-218, 1991.
Inspire Record 1389624 DOI 10.17182/hepdata.29359

The cross section and forward-backward muon charge asymmetry for the e + e − → μ + μ − γ reaction were measured to be σ =2.82±0.35 pb and A =−0.34±0.10 with the VENUS detector at TRISTAN at 〈√ s 〉=59.2GeV for an integrated luminosity of 53.5 pb −1 . The measured cross section agrees with the theoretical prediction. The asymmetry result is consistent with the electroweak prediction but not with the QED prediction at the level of 2 σ .

1 data table match query

No description provided.


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.