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

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

DELPHI

Collaboration

Feb, 1994

11 pages

Published in:

Phys.Lett.B 327 (1994) 386-396

DOI:

10.1016/0370-2693(94)90745-5

PDG:

{{\mathit Z}}

\rightarrow

{{\mathit \pi}^{0}}{{\mathit \gamma}}

Report number:

CERN-PPE-94-036,
CERN-PPE-94-36

Experiments:

CERN-LEP-DELPHI

View in:

CERN Document Server

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Abstract: (Elsevier)

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.

electron positron: colliding beams
colliding beams: electron positron
electron positron: annihilation
annihilation: electron positron
Z0: electroproduction
electroproduction: Z0
Z0: rare decay
rare decay: Z0
Z0: radiative decay
radiative decay: Z0

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Figures(0)

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