HEPData Search

We have measured, at an average centre-of-mass energy of 34.22 GeV a forward-backward charge asymmetry in the reaction e + e − → μ + μ − of value −0.161 ± 0.032. This demonstrates the existence of an axial vector neutral current with coupling strength of g e a g μ a =0.53 ± 0.10. We have also obtained a limit on the vector coupling strength of g e v g μ v <0.12. The Weinberg angle is found to be sin 2 θ W =0.29 +0.09 −0.11 . From the reaction e + e − → τ + τ − we have found g e a g τ a <0.34, g e v g τ v <0.55.

7 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

More…

Measurement of the Reaction $e^+ e^- \to \mu^+ \mu^-$ for 14-{GeV} $\le \sqrt{s} \le$ 36.4-{GeV}

The CELLO collaboration Behrend, H.J. ; Chen, C. ; Field, J.H. ; et al.

Z.Phys.C 14 (1982) 283, 1982.

Inspire Record 177216 DOI 10.17182/hepdata.16414

The reaction (e+e−→μ+μ−) has been measured between$\sqrt S= 14.0$ and$\sqrt S= 36.4$. The total cross section result is in good agreement with the QED prediction and the following Λ values have been obtained:Λ+=186 GeV,Λ−=101 GeV. The angular distribution at high energy ($\left( {\left. {\left\langle {\sqrt S } \right.} \right\rangle= 34.2 GeV} \right)$) shows a fitted charge asymmetry of −0.064±0.064 in agreement with theW-S model prediction of −0.092, corresponding to an axial coupling parametera2=4ga2=0.69±0.69.

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

Errors include contribution from systematics. Result based on fit(1 + cos(theta)**2 + q cos(theta)) to corrected angular distribution.

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.

4 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

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

More…

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.).

2 data tables

Table 1

No description provided.

Table 2

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.

Electroweak Effects in $e^+ e^- \to \mu^+ \mu^-$ at 29-{GeV}

Fernandez, E. ; Ford, William T. ; Read, Alexander L. ; et al.

Phys.Rev.Lett. 50 (1983) 1238, 1983.

Inspire Record 188749 DOI 10.17182/hepdata.20560

A measurement of the cross section for production of collinear muon pairs based upon a sample of about 3000 events observed in the MAC detector at the storage ring PEP is presented. From the angular asymmetry Aμμ=0.076±0.018 the axial-vector weak neutral coupling is found to be given by gAegAμ=0.31±0.08.

2 data tables

Table 1

Data on non-collinearity and angular distribution.

Table 2

Asymmetry measurement based on extrapolation of number of events to 4 PI acceptance.

WEAK NEUTRAL CURRENT EFFECTS IN e+ e- ---> mu+ mu- AT 29-GeV

Fernandez, E. ; Ford, William T. ; Read, Alexander L. ; et al.

SLAC-PUB-3133, 1983.

Inspire Record 190846 DOI 10.17182/hepdata.18659

None

2 data tables

Table 1

No description provided.

Table 2

Data extrapolated to full solid angle.

Weak Neutral Currents in e+ e- Collisions at s**(1/2)=29-GeV

Levi, M.E. ; Blocker, C.A. ; Strait, J. ; et al.

Phys.Rev.Lett. 51 (1983) 1941, 1983.

Inspire Record 191845 DOI 10.17182/hepdata.3281

The differential cross sections for lepton pair production in e+e− annihilation at 29 GeV have been measured and found to be in good agreement with the standard model of the electroweak interaction. With the assumption of e−μ−τ universality, the weak neutral-current couplings are determined to be ga2=0.23±0.05 and gv2=0.03±0.04.

8 data tables

Table 1

Numerical values supplied by M.Levi.

Table 2

Data requested from authors.

Table 3

Extrapolated to full angular range.

More…

Production and Muonic Decay of Heavy Quarks in e+ e- Annihilation at 34.5-GeV

The TASSO collaboration Althoff, M. ; Braunschweig, W. ; Kirschfink, F.J. ; et al.

Z.Phys.C 22 (1984) 219, 1984.

Inspire Record 194775 DOI 10.17182/hepdata.16252

The production of prompt muons ine+e− annihilation has been studied at centre of mass energies near 34.5 GeV. The measured semi-muonic branching ratios ofb andc quarks areB(b»Xμv) =0.117±0.028±0.01 andB(c→Xμv)=0.082 ±0.012a−0.01+0.02. The fragmentation functions of heavy quarks are hard, <zb>=0.85a−0.12–0.07+0.10+0.02 and <zc> =0.77a−0.07–0.11+0.05+0.03. Limits have been set on flavour changing neutral current decays:B(b→Xµ+µ−) <0.02 andB(b→Xµ+µ− (95% confidence level).

1 data table

Table 1

THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT MUONS.

Date

Collaboration

Subject_areas

Phrases

Reactions

Observables Reset

CM Energies (GeV)

Authors Reset

Azimuthal Correlations of ($\pi^+ \pi^-$) Pairs in Pion - Nucleus and Pion - Nucleon Interactions at $p$ = 40-{GeV}/$c$

Azimuthal Correlations of Identical Pions in Pion - Nucleus and Pion - Nucleon Interactions at $p=40$-{GeV}/$c$

Charge Asymmetry and Weak Interaction Effects in $e^+ e^- \to \mu^+ \mu^-$ and $e^+ e^- \to \tau^+ \tau^-$

Measurement of the Reaction $e^+ e^- \to \mu^+ \mu^-$ for 14-{GeV} $\le \sqrt{s} \le$ 36.4-{GeV}

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

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

Electroweak Effects in $e^+ e^- \to \mu^+ \mu^-$ at 29-{GeV}

WEAK NEUTRAL CURRENT EFFECTS IN e+ e- ---> mu+ mu- AT 29-GeV

Weak Neutral Currents in e+ e- Collisions at s**(1/2)=29-GeV

Production and Muonic Decay of Heavy Quarks in e+ e- Annihilation at 34.5-GeV