Measurements of the QED structure of the photon

OPAL Collaboration

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13 Scopus citations


The structure of both quasi-real and highly virtual photons is investigated using the reaction e+e- → e+e-μ+μ-, proceeding via the exchange of two photons. The results are based on the complete OPAL dataset taken at e+e- centre-of-mass energies close to the mass of the Z boson. The QED structure function Fγ2 and the differential cross-section dσ/dx for quasi-real photons are obtained as functions of the fractional momentum x from the muon momentum which is carried by the struck muon in the quasi-real photon for values of Q2 ranging from 1.5 to 400 GeV2. The differential cross-section dσ/dx for highly virtual photons is measured for 1.5 < Q2 < 30 GeV2 and 1.5 < P2 < 20 GeV2, where Q2 and P2 are the negative values of the four-momentum squared of the two photons such that Q2 > P2. Based on azimuthal correlations the QED structure functions FγA and FγB for quasi-real photons are determined for an average Q2 of 5.4 GeV2.

Original languageEnglish
Pages (from-to)409-425
Number of pages17
JournalEuropean Physical Journal C
Issue number3
StatePublished - 1 Jan 1999
Externally publishedYes

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)


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