Total cross section in γγ collisions at LEP

Abstract

The reaction e+e− → e+e−γ ∗γ ∗ → e+e− hadrons for quasi-real photons is studied using data from √s = 183 GeV up to 202 GeV. Results on the total cross sections σ (e+e− → e+e− hadrons) and σ (γ γ → hadrons) are given for the two- photon centre-of-mass energies 5 GeV Wγ γ 185 GeV. The total cross section of two real photons is described by a Regge parametrisation. We observe a steeper rise with the two-photon centre-of-mass energy as compared to the hadron–hadron and the photon–proton cross sections. The data are also compared to the expectations of different theoretical models.