Saturation and Critical Phenomena in DIS

TL;DR

The paper discusses how the observed decline in structure functions at low x and Q^2 in deep inelastic scattering may indicate a phase transition from a partonic gas to a liquid, analyzed through statistical and collective models.

Contribution

It introduces a novel interpretation of saturation phenomena as a phase transition, connecting parton dynamics with collective matter behavior in QCD.

Findings

Saturation linked to a phase transition in partonic matter.

Comparison of lepton-hadron and hadron-hadron collision phenomena.

Application of statistical and percolation models to DIS data.

Abstract

It is argued that the expected turn-down in $x- Q^2$ of the cross sections (structure functions $F_2(x,Q^2)$), assumed to result from the saturation of parton densities in the nucleon, is related to a phase transition from the (almost) ideal partonic gas, obeying Bjorken scaling, to a partonic "liquid". This can be quantified in the framework of statistical models, percolation and other approaches to collective phenomena of the strongly interacting matter. Similarities and differences between the case of lepton-hadron, hadron-hadron and nuclear collisions are discussed.