HEPData Search

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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 match query

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.

Precise measurement of Bhabha scattering at a center-of-mass energy of 57.77-GeV.

The VENUS collaboration Arima, T. ; Odaka, S. ; Ogawa, K. ; et al.

Phys.Rev.D 55 (1997) 19-39, 1997.

Inspire Record 421762 DOI 10.17182/hepdata.38325

Bhabha scattering at a center-of-mass energy of 57.77 GeV has been measured using the VENUS detector at KEK TRISTAN. The precision is better than 1% in scattering angle regions of |cosθ|⩽0.743 and 0.822⩽cosθ⩽0.968. A model-independent scattering-angle distribution is extracted from the measurement. The distribution is in good agreement with the prediction of the standard electroweak theory. The sensitivity to underlying theories is examined, after unfolding the photon-radiation effect. The q2 dependence of the photon vacuum polarization, frequently interpreted as a running of the QED fine-structure constant, is directly observed with a significance of three standard deviations. The Z0 exchange effect is clearly seen when the distribution is compared with the prediction from QED (photon exchanges only). The agreement with the standard theory leads us to constraints on extensions of the standard theory. In all quantitative discussions, correlations in the systematic error between angular bins are taken into account by employing an error matrix technique.

1 data table match query

Table 1

Cross section is integrated over the cos(theta ) bin.

Measurement of the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at $\sqrt{s}=52$-{GeV}

The VENUS collaboration Abe, Koya ; Amako, Katsuya ; Arai, Yasuo ; et al.

J.Phys.Soc.Jap. 56 (1987) 3767-3770, 1987.

Inspire Record 251276 DOI 10.17182/hepdata.38511

None

2 data tables match query

Table 1

No description provided.

Table 2

No description provided.

Measurement of the Processes $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at {PETRA}

The JADE collaboration Bartel, W. ; Becker, L. ; Bowdery, C. ; et al.

Z.Phys.C 19 (1983) 197, 1983.

Inspire Record 191231 DOI 10.17182/hepdata.45206

Cross sections for the reactionse+e−→e+e− (Bhabha scattering) ande+e−→γγ are measured for center-of-mass (c.m.) energies$\sqrt s $ between 12.0 and 34.6 GeV. The results agree with the predictions of Quantum Electrodynamics (QED) and the cut-off parameters are determined. From Bhabha scattering at the highest energy,$\left\langle {\sqrt s } \right\rangle= 34.6 GeV$, the 1 δ limits 0.12<sin2 ϑw<0.38 are obtained for the weak mixing angle. The higher order (α3) QED processese+e−→e+e−γ ande+e−→γγγ are also studied and are found to agree with the α3 QED predictions. A search for excited electrons is carried out by investigating the (e±γ) invariant mass distribution in the reactione+e−→e+e−γ.

3 data tables match query

Table 1

Total cross sections.

Table 2

Angular distribution.

Table 3

Angular distribution.

Update of electroweak parameters from Z decays

The ALEPH collaboration Buskulic, D. ; Decamp, D. ; Goy, C. ; et al.

Z.Phys.C 60 (1993) 71-82, 1993.

Inspire Record 354298 DOI 10.17182/hepdata.47312

Based on 520 000 fermion pairs accumulated during the first three years of data collection by the ALEPH detector at LEP, updated values of the resonance parameters of theZ are determined to beMZ=(91.187±0.009) GeV, ΓZ=(2.501±0.012) GeV, σhad0=(41.60±0.27) nb, andRℓ=20.78±0.13. The corresponding number of light neutrino species isNν=2.97±0.05. The forward-backward asymmetry in lepton-pair decays is used to determine the ratio of vector to axial-vector couplings of leptons:gV2(MZ2)/gA2(MZ2)=0.0052±0.0016. Combining this with ALEPH measurements of theb andc quark asymmetries and τ polarization gives sin2θWeff=0.2326±0.0013. Assuming the minimal Standard Model, and including measurements ofMW/MZ fromp$\bar p$ colliders and neutrino-nucleon scattering, the mass of the top quark is$M_{top} = 156 \pm \begin{array}{*{20}c} {22} \\ {25} \\ \end{array} \pm \begin{array}{*{20}c} {17} \\ {22Higgs} \\ \end{array} $ GeV.

15 data tables match query

Table 1

Data from 1990 running period.

Table 2

Data from 1990 running period.

Table 3

Data from 1990 running period.

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Measurement of the Processes $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at $\sqrt{s}=52$-{GeV}

The TOPAZ collaboration Adachi, I. ; Aihara, H. ; Dijkstra, H.B. ; et al.

Phys.Lett.B 200 (1988) 391-396, 1988.

Inspire Record 251921 DOI 10.17182/hepdata.30010

Differential cross sections for the processes e + e − → e + e − (Bhabha scattering) and e + e − → γγ have been measured with the TOPAZ detector at s =52 GeV . The results agree with the predictions of quantum electrodynamics (QED). The lower limits for the QED cut-off parameters have been obtained to be Λ + ⩾115 GeV and Λ − ⩾236 GeV for Bhabha scattering, and Λ + ⩾94 GeV and Λ − ⩾59 GeV for the reaction e + e − → γγ .

4 data tables match query

Table 1

Statistical errors only.

Table 2

Statistical errors only.

Table 3

Ratio of experimental data to prediction for lowest order QED. Statistical errors only.

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Measurement of radiative Bhabha and quasi-real Compton scattering.

The L3 collaboration Acciarri, M. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.

Phys.Lett.B 439 (1998) 183-196, 1998.

Inspire Record 473410 DOI 10.17182/hepdata.49339

We report on a study of radiative Bhabha and quasi-real Compton scattering at centre-of-mass energies between 50 GeV and 170 GeV, and 20 GeV and 140 GeV, respectively, using the L3 detector at LEP. The analysis is based on data corresponding to an integrated luminosity of 232.2 pb −1 . A total of 2856 radiative Bhabha and 4641 Compton scattering events are collected. Total and differential cross sections for both reactions are presented and found to be in good agreement with QED expectations. Our measurement of Compton scattering at the highest energies obtained so far is used to derive exclusion limits on the coupling λ for the on-shell production of an excited electron e ★ decaying into a γ e pair in the mass range 20 GeV

2 data tables match query

Table 1

Measured cross sections for radiative Bhabha scattering events.

Table 2

Measured cross sections for the quasi-real Compton scattering events.

A Study of Bhabha Scattering at {PETRA} Energies

The TASSO collaboration Braunschweig, W. ; Gerhards, R. ; Kirschfink, F.J. ; et al.

Z.Phys.C 37 (1988) 171, 1988.

Inspire Record 249557 DOI 10.17182/hepdata.45173

We report on high statistics Bhabha scattering data taken with the TASSO experiment at PETRA at center of mass energies from 12 GeV to 46.8 GeV. We present an analysis in terms of electroweak parameters of the standard model, give limits on QED cut-off parameters and look for possible signs of compositeness.

7 data tables match query

Table 1

Axis error includes +- 1/1 contribution (The overall uncertainty in the bin-to-bin polar acceptance due to shower corrections, trigger and reconstruction efficiencies was estimated to be less than 1% and was added in quadrature to the statistical errorsData have been corrected for qed radiative effects up to order alpha**3 (F.A.Berends, R.Kleiss, Nucl.Phys.B206(1983)61)//Weak radiative corrections have not yet been provided in a form of a Monte Carlo generator program, but are estimated to be negligible at PETRA energies (M.Bohm, A.Denner, W.Hollik, DESY-86-165)).

Table 2

Table 3

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Experimental Test of Electroweak Effects at {PETRA} Energies

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Grigull, R. ; et al.

Z.Phys.C 7 (1981) 289, 1981.

Inspire Record 156660 DOI 10.17182/hepdata.13818

The differential cross sections for Bhabha scattering and μ pair production, and the total τ pair cross section as measured by the PLUTO detector at PETRA, have been analyzed to extract information on the weak interaction of leptons. The data are compared with unified gauge theories. Since the observed electroweak effects are still consistent with zero (within errors) we can set experimental limits on neutral current parameters atQ2 values of 950 GeV2. In the framework of the standard SU(2)×U(1) model we find sin2Θw<0.52(95% c.l.). In the context of general singleZo models we can excludeZo masses of less than 40 GeV.

2 data tables match query

Table 1

No description provided.

Table 2

No description provided.

Test of {QED} in the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \mu^+ \mu^-$ at {CMS} Energies From 9.4-{GeV} to 31.6-{GeV}

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Grigull, R. ; et al.

Z.Phys.C 4 (1980) 269, 1980.

Inspire Record 152289 DOI 10.17182/hepdata.15600

None

2 data tables match query

Table 1

No description provided.

Table 2

No description provided.

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

Precise measurement of Bhabha scattering at a center-of-mass energy of 57.77-GeV.

Measurement of the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at $\sqrt{s}=52$-{GeV}

Measurement of the Processes $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at {PETRA}

Update of electroweak parameters from Z decays

Measurement of the Processes $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at $\sqrt{s}=52$-{GeV}

Measurement of radiative Bhabha and quasi-real Compton scattering.

A Study of Bhabha Scattering at {PETRA} Energies

Experimental Test of Electroweak Effects at {PETRA} Energies

Test of {QED} in the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \mu^+ \mu^-$ at {CMS} Energies From 9.4-{GeV} to 31.6-{GeV}