Measurement of the e+ e- ---> gamma gamma (gamma) cross-section at LEP energies

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 327 (1994) 386-396, 1994.
Inspire Record 373116 DOI 10.17182/hepdata.48343

The total and the differential cross sections for the reaction e + e − → γγ ( γ ) have been measured with the DELPHI detector at LEP using an integrated luminosity of 36.9 pb −1 . The results agree with the QED predictions and consequently there is no evidence for non-standard channels with the same experimental signature. The lower limits obtained on the QED cutoff parameters are Λ + > 143 GeV and Λ − > 120 GeV, and the lower bound on the mass of an excited electron with an effective coupling constant λ γ = 1 is 132 GeV/ c 2 . Upper limits on the branching ratios for the decays Z 0 → γγ , Z 0 → π 0 γ , Z 0 → ηγ and Z 0 → γγγ have been determined to be 5.5 × 10 −5 , 5.5 × 10 −5 , 8.0 × 10 −5 , and 1.7 × 10 −5 respectively. All the limits are at the 95% confidence level.

4 data tables

1990 energies are 88.223, 89.222, 90.217, 91.217, 92.209, 93.208 and 94.202 GeV.. 1991 energies are 88.465, 89.460, 90.208, 91.225, 91.954, 92.953, and 93.703 GeV.. 1992 energy is 91.278 GeV.

Average of all data.

No description provided.

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Studies of e+ e- ---> gamma gamma and gamma-gamma-gamma reactions

The TOPAZ collaboration Shimozawa, K. ; Fujimoto, J. ; Abe, T. ; et al.
Phys.Lett.B 284 (1992) 144-150, 1992.
Inspire Record 339575 DOI 10.17182/hepdata.29177

We have measured the cross section for γγ production with the TOPAZ detector in the energy region √ s =50.0–61.4 GeV. The observed cross section for γγ production integrated over |cos θ | ⩽ 0.77 is 50.2±0.8±2.2 pb at 〈√ s 〉=57.6 GeV and the ratio of this value to the QED prediction is 1.01±0.02±0.04. The angular distribution is in good agreement with the QED predictions, thereby setting limits on the compositeness scales, Λ L+R + =168 GeV, Λ L+R − =97 GeV, Λ L,R =141 GeV, Λ L,R − =81 GeV, and Λ L−R ± =68 GeV, at the 95% confidence level. The reaction e + e − → γγγ was also studied and was found consistent with the QED prediction.

11 data tables

No description provided.

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A Study of the Reaction $e^+ e^- \to \gamma \gamma$ at {LEP}

The OPAL collaboration Akrawy, M.Z. ; Alexander, G. ; Allison, J. ; et al.
Phys.Lett.B 241 (1990) 133-140, 1990.
Inspire Record 294809 DOI 10.17182/hepdata.29717

The pure QED reaction e + e − → γγ has been studied at centre of mass energies around the mass of the Z 0 boson using data recorded by the OPAL detector at LEP. The results are in good agreement with the QED prediction. Lower limits on the cutoff parameters of the modified electron propagator are found to be Λ + >89 GeV and Λ. The lower limit on the mass of an excited electron is 82 GeV assuming the coupling constant λ =1. Upper limits on the branching ratios of Z 0 → γγ , Z 0 → π 0 γ and Z 0 → ηγ are set at 3.7×10 −4 , 3.9×10 −4 and 5.8×10 −4 respectively. Two events from the reaction e + e − → γγγ have been observed, consistent with the QED prediction. An upper limit on the branching ratio of Z 0 → γγγ is set at 2.8×10 −4 . All the limits are given at 95% confidence level.

2 data tables

No description provided.

Data read from graph.


Measurement of the Differential Cross-sections of $e^+ e^- \to \gamma \gamma$ and $e^+ e^- \to \gamma \gamma \gamma$ at $\sqrt{s}=55$-{GeV}, 56-{GeV}, 56.5-{GeV} and 57-{GeV} and Search for Unstable Photino Pair Production

The VENUS collaboration Abe, K. ; Amako, K. ; Arai, Y. ; et al.
Z.Phys.C 45 (1989) 175, 1989.
Inspire Record 280669 DOI 10.17182/hepdata.15298

Differential cross sections fore+e−→γγ have been measured at center-of-mass energies of 55, 56, 56.5 and 57 GeV. The results are in good agreement with those predicted by QED. Possible deviations from QED are studied in terms of contact interactions, and the limits on compositeness scales are obtained. Using events with a gramma pair in the final state, a search is made for the pair production of unstable photons,\(e^ +e^ -\to \tilde \gamma\tilde \gamma \). No candidate events were found and a new limit on the photino mass is obtained.

11 data tables

No description provided.

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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

Statistical errors only.

Statistical errors only.

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

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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

No description provided.

No description provided.


Experimental Study of the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at 29-{GeV}

Derrick, M. ; Gan, K.K. ; Kooijman, P. ; et al.
Phys.Rev.D 34 (1986) 3286, 1986.
Inspire Record 18585 DOI 10.17182/hepdata.23442

This paper reports measurements of the differential cross sections for the reactions e+e−→e+e− (Bhabha scattering) and e+e−→γγ (γ-pair production). The reactions are studied at a center-of-mass energy of 29 GeV and in the polar-angular region ‖costheta‖<0.55. A direct cross-section comparison between these two reactions provides a sensitive test of the predictions of quantum electrodynamics (QED) to order α3. When the ratio of γ-pair to Bhabha experimental cross sections, integrated over ‖costheta‖<0.55, is divided by the same ratio predicted from α3 QED theory, the result is 1.007±0.009±0.008. The 95%-confidence limits on the QED-cutoff parameters are Λ+>154 GeV and Λ−>220 GeV for Bhabha scattering, and Λ+>59 GeV and Λ−>59 GeV for γ-pair production.

1 data table

No description provided.


Tests of Quantum Electrodynamics With 2, 3 and 4 Photon Final States From $e^+ e^-$ Annihilation at $\sqrt{s}=29$-{GeV}

Fernandez, E. ; Ford, William T. ; Qi, N. ; et al.
Phys.Rev.D 35 (1987) 1, 1987.
Inspire Record 230165 DOI 10.17182/hepdata.23424

High-precision measurements of electron-positron annihilation into final states of two, three, and four photons are presented. The data were obtained with the MAC detector at the PEP storage ring of the Stanford Linear Accelerator Center, at a center-of-mass energy of 29 GeV. The measured e+e−→γγ differential cross section is used to test the validity of quantum electrodynamics (QED) in this energy range; it agrees well with QED, and the limit on cutoff parameters for the electron propagator is Λ>66 GeV. The measurement of e+e−→γγγ is used to test the QED calculations of order α3 and to search for anomalies that would indicate the existence of new particles; the agreement with QED is excellent and no anomalies are found. Two events from the reaction e+e−→γγγγ are found, in agreement with the QED prediction.

3 data tables

Errors are combined statistical and systematics.

No description provided.

Two 4gamma events are observed corresponding to a cross section of 0.02 PB.


Precision Test of {QED} by Direct Comparison of $e^+ e^- \to \gamma \gamma$ and $e^+ e^- \to e^+ e^-$ at 29-{GeV}

Derrick, M. ; Gan, K.K. ; Kooijman, P. ; et al.
Phys.Lett.B 166 (1986) 468-472, 1986.
Inspire Record 17510 DOI 10.17182/hepdata.30311

The ratio of differential cross sections for the reactions e + e − → γγ and e + e − → e + e − is measured at s = 29 GeV in the central polar angle region, |cos θ | < 0.55, and compared to the same ratio calculated by QED to order α 3 . The ratio of these ratios, integrated over this angular region, is 1.007±0.009±0.008, demonstrating excellent agreement between theory and experiment. The 95% confidence limits on the QED cut-off parameters for the γγ final state are Λ + > 59 GeV and Λ - > 59 GeV.

1 data table

No description provided.


Photon Pair Production by $e^+ e^-$ Annihilation and Search for Supersymmetric Photinos at Energies > 40-{GeV}

The TASSO collaboration Althoff, M. ; Braunschweig, W. ; Kirschfink, F.J. ; et al.
Z.Phys.C 26 (1984) 337, 1984.
Inspire Record 204486 DOI 10.17182/hepdata.16194

None

2 data tables

No description provided.

No description provided.