Total $\gamma^*$ p Cross Section

TL;DR

This paper develops a model based on Gribov's ideas to describe the total gamma* p cross section across a wide range of photon virtualities and energies, successfully matching experimental data and elucidating soft and hard process contributions.

Contribution

A simple, quantitative model that describes the transition between soft and hard photon-proton interactions at high energies, including separation parameters and contributions to cross sections.

Findings

Determined separation parameters for soft and hard interactions.

Used the additive quark model for soft contributions.

Achieved good agreement with the ratio σ_L/σ_T.

Abstract

This paper shows that the approach based on Gribov's ideas for the photon-proton interaction, is able to describe the experimental data over a wide range of photon virtualities $Q^2 = 0 - 100 GeV^2$ and energies $\sqrt{s} = W = 3 - 300 GeV$. A simple model is suggested which provides a quantitative way of describing the matching between short and long distances (between "soft" and "hard" processes) in photon-proton interaction at high energy. The main results of our analysis are: (i) the values of the separation parameters differentiating the "soft" and "hard" interactions are determined; (ii) the additive quark model can be used to calculate the "soft" contribution to the photon - proton interaction; (iii) a good description of the ratio $\sigma_L/\sigma_T$ is obtained ; and (iv) a considerable contribution of the "soft" process at large $Q^2$, and of "hard" processes at small $Q^2$ was found.