Measurement of QED photon structure functions in tagged photon-photon collisions at LEP

The muon pair production in the process e(+)e(-) --> e(+)e(-)mu(+)mu(-) , in the single-tag mode, is studied, using the data taken at LEP with the DELPHI detector during the years 1992-1995. The integrated luminosity is 138.5 pb(-1) Distributions of different event variables have been obtained for the whole Q(2)-range accessible at LEP1 (from several units to several hundred GeV2/c(4)) and compared with Monte Carlo predictions based on QED. Selected events are used to extract the leptonic photon structure function F-2(gamma). Azimuthal correlations are studied to measure additional structure functions F-A(gamma) and F-B(gamma), which originate from interference terms of the scattering amplitudes. They are found to be significantly different from zero and consistent with QED predictions.