Nonlinear evolution in the colour glass condensate

Abstract

The Colour Glass Condensate is used as an effective theory to study Quantum Chromodynamics at high energies in various scattering processes. Several evolution equations are discussed, in particular the JIMWLK (Jalilian-Marian–Iancu– McLerran–Weigert–Leonidov–Kovner) equation. This is studied in two equivalent pictures, namely the Fokker–Planck formalism and the Langevin formalism. From the latter, we show how BFKL (Balitsky–Fadin–Kuraev–Lipatov) dynamics emerge in the dilute limit. This is discussed further in Paper [II]. From the Fokker–Planck formalism, we use the Gaussian Approximation scheme to study several different types of correlators of fundamental Wilson lines. The 6-point correlators that appear in the next-to-leading order BK (Balitsky–Kovchegov) equation are calculated – their numerical implementation is covered in Paper [III]. Finally, the Gaussian Approximation is extended as a means to derive an evolution equation for the so-called odderon. Simple correlators are also calculated to see how their parametric equations are modified. The extended approximation scheme and the numerical implementation of the odderon are studied further in Paper [I].