Saturation at low $x$

TL;DR

This paper reviews the current understanding of saturation phenomena at low Bjorken-x in deep inelastic scattering, covering theoretical foundations, experimental evidence, and implications for future experiments like THERA.

Contribution

It provides a comprehensive overview of the theoretical proof, recent progress, and experimental status of saturation effects in high-density QCD at low x.

Findings

Saturation hypothesis has solid theoretical proof

Progress in high parton density QCD over recent years

Compilation of theoretical and experimental knowledge on saturation scale Q_s(x)

Abstract

This talk is an attempt to review all our knowledge on saturation at low $x$ both theoretical and experimental, to stimulate a search for saturation effects at THERA. The main goals of this presentation are 1. To discuss an intuitive picture of the deep inelastic scattering that leads to the saturation of the parton densities; 2. To show that the saturation hypothesis has solid theoretical proof; 3. To report on the theoretical progress that has been made over the past two years in high parton density QCD, and on the property of the saturation phase that emerges from the theory that has been developed; 4. To collect all that we know theoretically and experimentally about the saturation scale $Q_s(x)$ .