Proton structure, Partons, QCD, DGLAP and beyond

TL;DR

This paper introduces deep-inelastic scattering to explore proton substructure, reviews QCD and DGLAP evolution, and discusses parton distributions and their relevance for LHC predictions, including low-x behavior and non-linear effects.

Contribution

It provides an accessible overview of proton structure, emphasizing the role of QCD and DGLAP equations, and discusses recent insights into low-x phenomena and non-linear contributions.

Findings

Parton distributions are crucial for LHC predictions.

Evidence suggests non-linear effects at low x.

DGLAP evolution describes parton density changes with energy.

Abstract

We present an introductory discussion of deep-inelastic lepton-proton scattering as a means to probe the substructure of the proton. A resume of QCD is given, emphasizing the running of the coupling constant and the DGLAP evolution equations for the parton densities. The determination of parton distributions is discussed and their importance for predictions of processes at the LHC is emphasized. Going beyond the pure DGLAP regime, we briefly discuss the behaviour of parton densities at low x, and the evidence for non-linear absorptive contributions.