Saturation and geometrical scaling

TL;DR

This paper explores how geometrical scaling arises from nonlinear QCD evolution equations, linking particle spectra dependence to the saturation momentum and comparing theoretical predictions with experimental data.

Contribution

It demonstrates that geometrical scaling naturally emerges from nonlinear QCD dynamics and provides a framework to analyze experimental data across different systems.

Findings

Particle spectra depend on the ratio pT/Qs in the scaling region.

The energy dependence of spectra is governed by the saturation momentum Qs.

Experimental data supports the presence of geometrical scaling in various systems.

Abstract

We discuss emergence of geometrical scaling as a consequence of the nonlinear evolution equations of QCD, which generate a new dynamical scale, known as the saturation momentum: Qs. In the kinematical region where no other energy scales exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on the ratio pT=Qs, and the energy dependence enters solely through the energy dependence of the saturation momentum. We confront the hypothesis of GS in different systems with experimental data.