$\gamma p$ and $\gamma \gamma$ scattering from $\bar{p}p$, $pp$ forward amplitudes in a QCD eikonal model with a dynamical gluon mass

Abstract

We examine the $\gamma p$ photoproduction and the hadronic $\gamma \gamma$ total cross sections by means of a QCD eikonal model with a dynamical infrared mass scale. In this model, where the dynamical gluon mass is the natural regulator for the tree level gluon-gluon scattering, the $\gamma p$ and $\gamma \gamma$ total cross sections are derived from the $pp$ and $\bar{p}p$ forward scattering amplitudes assuming vector meson dominance and the additive quark model. We show that the validity of the cross section factorization relation ${\sigma }_{pp}/{\sigma }_{\gamma p}={\sigma }_{\gamma p}/{\sigma }_{\gamma \gamma }$ is fulfilled depending on the Monte Carlo model used to unfold the hadronic $\gamma \gamma$ cross section data, and we discuss in detail the case of $\sigma (\gamma \gamma \to hadrons)$ data with $W_{\gamma \gamma }>10$ GeV unfolded by the Monte Carlo generators PYTHIA and PHOJET. The data seems to favor a mild dependence with the energy of the probability ($P_{had}$) that the photon interacts as a hadron.

16 pages, 3 figures; misprints corrected; to appear in Phys. Rev. D

Cited by in corpus (4)

• Gluon mass generation in the PT-BFM scheme
• Survival probability of large rapidity gaps in a QCD model with a dynamical infrared mass scale
• The small $x$ behavior of the gluon structure function from total cross sections
• Multiplicity of photohadronization and photon--hadron scaling violation