CGC/saturation approach: an impact-parameter dependent model for diffraction production in DIS

TL;DR

This paper develops an impact-parameter dependent saturation model within the CGC framework to describe diffraction production in deep inelastic scattering, fitting H1 and ZEUS data and highlighting the non-geometric scaling behavior of diffractive processes.

Contribution

It introduces a novel impact-parameter dependent saturation model based on analytical solutions of evolution equations in the CGC framework for diffraction production.

Findings

Successfully fits $x_ ext{pom}$ and $eta$ dependence of data

Describes $Q$ dependence of measured cross sections

Highlights non-geometric scaling in diffraction production

Abstract

In the paper we discussed the evolution equations for diffractive production in the framework of CGC/saturation approach, and found the analytical solutions for several kinematic regions. The most impressive features of these solutions are, that diffractive production does not exibit geometric scaling behaviour i.e. being a function of one variable. Based on these solutions, we suggest an impact parameter dependent saturation model, which is suitable for describing diffraction production both deep in the saturation region, and in the vicinity of the saturation scale. Using the model we attempted to fit the combined data on diffraction production from H1 and ZEUS collaborations. We found that we are able describe both $x_\pom$ and $\beta$ dependence, as well as $Q$ behavior of the measured cross sections. In spite of the sufficiently large $\chi^2/d.o.f.$ we believe that our description provides an initial impetus to find a fit of the experimental data, based on the solution of the CGC/saturation equation, rather than on describing the diffraction system in simplistic manner, assuming that only quark-antiquark pair and one extra gluons, are produced.