Non-linear QCD dynamics in two-photon interactions at high energies

Abstract

Perturbative QCD predicts that the growth of the gluon density at high energies should saturate, forming a Color Glass Condensate (CGC), which is described in mean field approximation by the Balitsky-Kovchegov (BK) equation. In this paper we study the $\gamma \gamma$ interactions at high energies and estimate the main observables which will be probed at future linear colliders using the color dipole picture. We discuss in detail the dipole - dipole cross section and propose a new relation between this quantity and the dipole scattering amplitude. The total $\gamma \gamma$, ${\gamma }^{\ast }{\gamma }^{\ast }$ cross-sections and the real photon structure function $F_2^{\gamma }(x,Q^2)$ are calculated using the recent solution of the BK equation with running coupling constant and the predictions are compared with those obtained using phenomenological models for the dipole-dipole cross section and scattering amplitude. We demonstrate that these models are able to describe the LEP data at high energies, but predict a very different behavior for the observables at higher energies. Therefore we conclude that the study of $\gamma \gamma$ interactions can be useful to constrain the QCD dynamics.

11 pages, 5 figures. Version to be published in European Physical Journal C

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Cited by in corpus (6)

• Double vector meson production in photon - hadron interactions at hadronic colliders
• Double vector meson production in $\gamma \gamma$ interactions at hadronic colliders
• A phenomenological analysis of the nonperturbative QCD contributions for the photon wave function
• Double vector meson production in the International Linear Collider
• Running coupling and pomeron loop effects on inclusive and diffractive DIS cross sections
• Effects of gluon number fluctuations on photon - photon collisions at high energies