Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP

Muon pair production in the process is studied using the data taken at LEP1 () with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb. The QED predictions have been tested over the whole range accessible at LEP1 (from several GeV to several hundred GeV) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function . Azimuthal correlations are used to obtain information on additional structure functions, and , which originate from interference terms of the scattering amplitudes. The measured ratios and are significantly different from zero and consistent with QED predictions. Received: 23 February 2000 / Revised version: 7 December 2000 / Published online: 23 February 2001