F_2^gamma at low Q^2 and sigma_{\gamma \gamma} at high energies

TL;DR

This paper develops a parametrisation of the photon structure function at low Q^2, combining VMD and QCD models, to describe existing data and predict cross sections at future collider energies.

Contribution

It introduces a new combined parametrisation of the photon structure function applicable at low Q^2, extending previous models to better fit experimental data and make predictions for future experiments.

Findings

The parametrisation fits existing experimental data well.

Predictions for cross sections at future collider energies are provided.

The model successfully combines VMD and QCD components for low Q^2 regions.

Abstract

The parametrisation of the photon structure function in the low Q^2 region is formulated. It includes the VMD contribution and the QCD improved parton model component suitably extrapolated to the low Q^2 region. The parametrisation describes reasonably well existing experimental data on sigma_{\gamma \gamma} for real photons and the low Q^2 data on sigma_{\gamma^* \gamma}. Predictions for sigma_{\gamma \gamma} and for sigma_{\gamma^* \gamma} for energies which may be accesssible in future linear colliders are also given.