Direct measurement of leptonic coupling asymmetries with polarized Zs

The SLD collaboration Abe, K. ; Akagi, T. ; Allen, N.J. ; et al.
Phys.Rev.Lett. 79 (1997) 804-808, 1997.
Inspire Record 442260 DOI 10.17182/hepdata.19552

We present direct measurements of the $Z~0$-lepton coupling asymmetry parameters, $A_e$, $A_\mu$, and $A_\tau$, based on a data sample of 12,063 leptonic $Z~0$ decays collected by the SLD detector. The $Z$ bosons are produced in collisions of beams of polarized $e~-$ with unpolarized $e~+$ at the SLAC Linear Collider. The couplings are extracted from the measurement of the left-right and forward-backward asymmetries for each lepton species. The results are: $A_e=0.152 \pm 0.012 {(stat)} \pm 0.001 {(syst)}$, $A_\mu=0.102 \pm 0.034 \pm 0.002$, and $A_\tau=0.195 \pm 0.034 \pm 0.003$.

1 data table match query

No description provided.


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.


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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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.


Determination of $Z^0$ resonance parameters and couplings from its hadronic and leptonic decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Nucl.Phys.B 367 (1991) 511-574, 1991.
Inspire Record 317493 DOI 10.17182/hepdata.33016

From measurements of the cross sections for e + e − → hadrons and the cross sections and forward-backward charge-asymmetries for e e −→ e + e − , μ + μ − and π + π − at several centre-of-mass energies around the Z 0 pole with the DELPHI apparatus, using approximately 150 000 hadronic and leptonic events from 1989 and 1990, one determines the following Z 0 parameters: the mass and total width M Z = 91.177 ± 0.022 GeV, Γ Z = 2.465 ± 0.020 GeV , the hadronic and leptonic partial widths Γ h = 1.726 ± 0.019 GeV, Γ l = 83.4 ± 0.8 MeV, the invisible width Γ inv = 488 ± 17 MeV, the ratio of hadronic over leptonic partial widths R Z = 20.70 ± 0.29 and the Born level hadronic peak cross section σ 0 = 41.84±0.45 nb. A flavour-independent measurement of the leptonic cross section gives very consistent results to those presented above ( Γ l = 83.7 ± 0.8 rmMeV ). From these results the number of light neutrino species is determined to be N v = 2.94 ±0.10. The individual leptonic widths obtained are: Γ e = 82.4±_1.2 MeV, Γ u = 86.9±2.1 MeV and Γ τ = 82.7 ± 2.4 MeV. Assuming universality, the squared vector and axial-vector couplings of the Z 0 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 eff = 1.003 ± 0.011 and sin 2 θ W eff = 0.241 ± 0.009. Within the Minimal Standard Model (MSM), the results can be expressed in terms of a single parameter: sin 2 θ W M ̄ S = 0.2338 ± 0.0027 . All these values are in good agreement with the predictions of the MSM. Fits yield 43< m top < 215 GeV at the 95% level. Finally, the measured values of Γ Z and Γ inv are used to derived lower mass bounds for possible new particles.

8 data tables match query

Forward-backward asymmetry within the polar angular range 44 < THETA < 136 degrees and acollinearity < 10 degrees.. Overall systematic error is 0.005 not included.

Forward-backward asymmetry after t-channel subtraction but in the polar angular range 44 < THETA < 136 degrees and acollinearity < 10 degrees.. Overall systematic error is 0.005 not included.

Forward-backward asymmetry calculated using the counting method. Data are corrected for full solid angle, but not for cuts on momenta or acollinearity.. Additional systematic error is 0.005.

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Tests of the standard model and constraints on new physics from measurements of fermion pair production at 189-GeV to 209-GeV at LEP

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 33 (2004) 173-212, 2004.
Inspire Record 628491 DOI 10.17182/hepdata.43174

Cross-section and angular distributions for hadronic and lepton-pair final states in e+e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The measurements are used to determine the electromagnetic coupling constant alphaem at LEP2 energies. In addition, the results are used together with OPAL measurements at 91-183 GeV within the S-matrix formalism to determine the gamma-Z interference term and to make an almost model-independent measurement of the Z mass. Limits on extensions to the Standard Model described by effective four-fermion contact interactions or the addition of a heavy Z boson are also presented.

3 data tables match query

Measured forward backward asymmetries for MU+ MU- production. The data are corrected to no interference between initial and final state radiation.

Measured forward backward asymmetries for TAU+ TAU- production. The data are corrected to no interference between initial and final state radiation.

Measured forward backward asymmetries for E+ E- production.


A Measurement of Electroweak Effects in the Reaction $e^+ e^- \to \tau^+ \tau^-$ at 35-{GeV} and 42.4-{GeV}

The TASSO collaboration Braunschweig, W. ; Gerhards, R. ; Kirschfink, F.J. ; et al.
Z.Phys.C 43 (1989) 549, 1989.
Inspire Record 277662 DOI 10.17182/hepdata.15454

We report on total cross section and forward backward charge asymmetry measurements of the reactione+e− → τ+τ− at centre of mass energies of 35.0 GeV and 42.4 GeV using the TASSO detector. Including previous data an analysis in terms of electroweak parameters of the standard model is presented, and lower limits on mass scale parameters of residual contact interactions are given. A combined analysis of electroweak couplings using all our results on leptonic reactionse+e−→l+l− has been performed.

1 data table match query

No description provided.


A Search for substructure of leptons and quarks with the CELLO detector

The CELLO collaboration Behrend, H.J. ; Criegee, L. ; Field, J.H. ; et al.
Z.Phys.C 51 (1991) 149-156, 1991.
Inspire Record 301727 DOI 10.17182/hepdata.14981

Differential cross section data of the CELLO experiment on pair production of muons, taus, and heavy quarks ine+e−-annihilation are presented and analysed, together with our data on Bhabha scattering, in terms of compositeness effects characterized by the mass scale Λ. We discuss difficulties in the combination of limits Λ from different experiments. The appropriate parameter to combine different results turns out to be ɛ=±1/Λ2, which is in contrast to Λ Gaussian distributed.

2 data tables match query

Charge asymmetry for charm quarks derived from the differential cross section data.

Charge asymmetry for bottom quarks derived from the differential cross section data.


Measurements of Tau Lepton Production and Decay

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Lackas, W. ; et al.
Z.Phys.C 28 (1985) 1, 1985.
Inspire Record 213241 DOI 10.17182/hepdata.16019

We have studied 419 τ pair events produced in the reactione+e−→τ+ τ− at a c.m. energy of 34.6 GeV. We measure the cross section and angular distribution, as well as the decay branching ratios. The production characteristics are consistent with the Standard Electroweak Model predictions of γ andZ0 interference. The branching ratios are generally consistent with the τ decaying according to standard weak interaction principles, but we observe somewhat more decays resulting in single charged hadrons plus neutrals than are predicted by present theory.

1 data table match query

Asymmetry based on fits to angular distribution.


Tau Lepton Production and Decay at {PETRA} Energies

The JADE collaboration Bartel, W. ; Becker, L. ; Cords, D. ; et al.
Phys.Lett.B 161 (1985) 188, 1985.
Inspire Record 220695 DOI 10.17182/hepdata.30350

The production and decay of τ-pairs was studied with the JADE detector at PETRA at center-of-mass energies of 30 ⩽√ s ⩽ 46.78 GeV. The total production cross section for τ-pairs agreed with QED predictions to order α 3 . Lower limits on QED cut-off parameters of Λ + > 285 GeV and Λ − > 210 GeV at 95% confidence level were ontained. The decay branching fractions into one and three charged particles were determined to be (86.1 ± 0.5 ± 0.9)% and (13.6±0.5 ±0.80)%. In the angular distributions a forward-backward asymmetry was observed, from which the axial-vector weak charge to the τ was determined to be a τ = −0.74 ± 0.22 in agreement with the standard model. An analysis of the process e + e − → τ + τ − γ showed agreement with QED calculations to O(α 3 ).

2 data tables match query

Forward-backward asymmetry determined from fit to angular distribution of form N*(1 + cos(theta)**2 + (3/8)*A*cos(theta)).

Study of radiative tau events.