2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 14, 511-523
DOI 10.1007/s100520000362

The components of the $\gamma^* \gamma^*$ cross section

E. Gotsman - E. Levin - U. Maor - E. Naftali

School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Science, Tel Aviv University,
Tel Aviv, 69978, Israel

Received: 12 January 2000 / Published online: 6 April 2000 - © Springer-Verlag 2000

Abstract
We extend our previous treatment of the $\gamma^{*}$p cross section based on Gribov's hypothesis to the case of photon-photon scattering. With the aid of two parameters, determined from the experimental data, we separate the interactions into two categories corresponding to short ("soft'') and long ("hard'') distance processes. The photon-photon cross section thus receives contributions from three sectors, soft-soft, hard-hard and hard-soft. The additive quark model is used to describe the soft-soft sector, pQCD the hard-hard sector, while the hard-soft sector is determined by relating it to the $\gamma^{*}p$ system. We calculate and display the behaviour of the total photon-photon cross section and its various components and polarizations for different values of energy and virtuality of the two photons, and discuss the significance of our results.


Copyright Società Italiana di Fisica, Springer-Verlag 2000