Physical limits in the Color Dipole Model Bounds

Abstract

The ratio of the cross sections for the transversely and longitudinally virtual photon polarizations, $\sigma^{\gamma^{*}p}_{L/T}$, at high photon-hadron energy scattering is studied. I investigate the relationship between the gluon distribution obtained using the color dipole model and standard gluons obtained from the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution and the Altarelli-Martinelli equations. It is shown that the color dipole bounds are dependent on the gluon distribution behavior. This behavior is considered by the expansion and Laplace transform methods. Numerical calculations and comparison with the color dipole model (CDM) bounds can indicate the range of validity of this method at small dipole sizes, $r\sim 1/Q{\ll}1/Q_{s}$.