Eur. Phys. J. C 23, 513-526 (2002)
https://doi.org/10.1007/s100520200893

Saturation model for two-photon interactions at high energies

¹ High Energy Physics, Uppsala University, 75 121 Uppsala, Sweden
² H. Niewodniczański Institute of Nuclear Physics, 31-342 Kraków, Poland
³ Institute of Physics, Jagellonian University, 30-059 Kraków, Poland

Received: 1 November 2001
Published online: 15 March 2002

Abstract

We formulate and analyse a saturation model for the total γγ and γ^*γ^* cross-sections and for the real photon structure function F₂^γ(x,Q²). The model is based on a picture in which the γ^*γ^* total cross-section for arbitrary photon virtualities is driven by the interaction of colour dipoles into which the virtual photons fluctuate. The cross-section describing this interaction is assumed to satisfy the saturation property with the saturation radius taken from the Golec-Biernat and Wüsthoff analysis of the γ^*p interaction at HERA. The model is supplemented by the QPM and non-pomeron reggeon contributions. The model gives a very good description of the data on the γγ total cross-section, on the photon structure function F₂^γ(x,Q²) at low x and on the γ^*γ^* cross-section extracted from LEP double tagged events. The production of heavy flavours in γγ collisions is also studied. Predictions of the model for the very high energy range which will be probed at future linear colliders are given.