Direct measurement of leptonic coupling asymmetries with polarized Z's.

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.


$\tau$ Production and Decay With the Cello Detector at {PETRA}

The CELLO collaboration Behrend, H.J. ; Criegee, L. ; Dainton, J.B. ; et al.
Phys.Lett.B 222 (1989) 163-172, 1989.
Inspire Record 276859 DOI 10.17182/hepdata.29824

The reaction e + e − → τ + τ − has been studied at centre of mass energies between 14.0 and 46.8 GeV with the CELLO detector at the PETRA e + e − collider. We present results for the cross section σ τ and the charge asymmetry A τ . The results are in good agreement with the standard model. We have also measured the topological decay rates BR 1 , BR 3 and BR 5 for the inclusive decay of the τ lepton into one, three and five charge particles. The results confirm and improve earlier CELLO measurements at other energies. We find for the combined values at all energies BR 1 = (84.9 ± 0.4 ± 0.3)%, BR 3 = (15.0 ± 0.4 ± 0.3)% and BR 5 = (0.16 ± 0.13 ± 0.04)%.

1 data table match query

Corrected for radiative effects and background contributions.


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.


Coupling Strengths of Weak Neutral Currents From Leptonic Final States at 22-{GeV} and 34-{GeV}

The CELLO collaboration Behrend, H.J. ; Chen, C. ; Fenner, H. ; et al.
Z.Phys.C 16 (1983) 301, 1983.
Inspire Record 180756 DOI 10.17182/hepdata.16385

Differential cross sections fore+e−→e+e−, τ+, τ- measured with the CELLO detector at\(\left\langle {\sqrt s } \right\rangle= 34.2GeV\) have been analyzed for electroweak contributions. Vector and axial vector coupling constants were obtained in a simultaneous fit to the three differential cross sections assuming a universal weak interaction for the charged leptons. The results,v2=−0.12±0.33 anda2=1.22±0.47, are in good agreement with predictions from the standardSU(2)×U(1) model for\(\sin ^2 \theta _w= 0.228\). Combining this result with neutrino-electron scattering data gives a unique axial vector dominated solution for the leptonic weak couplings. Assuming the validity of the standard model, a value of\(\sin ^2 \theta _w= 0.21_{ - 0.09}^{ + 0.14}\) is obtained for the electroweak mixing angle. Additional vector currents are not observed (C<0.031 is obtained at the 95% C.L.).

1 data table match query

Combined MU and TAU asymmetry. See PL 114B(1982)282 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1234> RED = 1234 </a>) and ZP C14(1982)283 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1245> RED = 1245 </a>) for individual asymmetry measurements.


Measurement of $e^+ e^- \to \tau^+ \tau^-$ at High-energy and Properties of the $\tau$ Lepton

The CELLO collaboration Behrend, H.J. ; Chen, C. ; Fenner, H. ; et al.
Phys.Lett.B 114 (1982) 282-286, 1982.
Inspire Record 177224 DOI 10.17182/hepdata.6667

The e + e − → τ + τ − process has been measured using the CELLO detector at a mean total centre of mass energy of 34.2 GeV using essentially all the decay channels of the τ lepton. The measured cross section yields R τ =1.03±0.05 (stat)±0.07 (syst). Topological branching fraction are given for τ → 1, 3 or 5 charged tracks. The angular distribution shows a clear 1 + cos 2 θ dependance with a forward-backward asymmetry of -0.103 ± 0.052 corresponding to an axial-vector coupling a τ of the τ to the weak neutral current given by a τ =−1.12 ± 0.57.

1 data table match query

Forward-backward asymmetry based on 1 + (cos(theta))**2 + bcos(theta) fit for angular distribution.


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).


Measurement of the tau polarisation at LEP.

The ALEPH collaboration Heister, A. ; Schael, S. ; Barate, R. ; et al.
Eur.Phys.J.C 20 (2001) 401-430, 2001.
Inspire Record 555653 DOI 10.17182/hepdata.49751

The polarisation of $\tau$'s produced in Z decay is measured using 160 pb$^{-1}$ of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters ${\cal A}_e = 0.1504 \pm 0.0068 $ and ${\cal A}_{\tau} = 0.1451 \pm 0.0059$ which are consistent with the hypothesis of $e$-$\tau$ universality. Assuming universality, the value ${\cal A}_{e{-}\tau} = 0.1474 \pm 0.0045$ is obtained from which the effective weak mixing angle $\sin^2 {\theta_{\mathrm{W}}^{\mathrm{eff}}} =0.23147 \pm 0.00057 $ is derived.

1 data table match query

No description provided.


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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An improved direct measurement of leptonic coupling asymmetries with polarized Z bosons.

The SLD collaboration Abe, Koya ; Abe, Kenji ; Abe, T. ; et al.
Phys.Rev.Lett. 86 (2001) 1162-1166, 2001.
Inspire Record 534735 DOI 10.17182/hepdata.41720

We present final measurements of the Z boson-lepton coupling asymmetry parameters Ae, Amu, and Atau with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure Ae = 0.1544 +- 0.0060, Amu = 0.142 +- 0.015, and Atau = 0.136 +- 0.015. Combined with our left-right asymmetry measured from hadronic decays, we find Ae = 0.1516 +- 0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin**2 theta^{eff}_W = 0.23098 +- 0.00026.

1 data table match query

No description provided.


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

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4 data tables match query

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