Correlations and discreteness in nonlinear QCD evolution

2006/01/31 by N. Armesto, José Guilherme Milhano, J. G. Milhano · 2 citations
Mathematics · Physics and Astronomy · #Color-glass condensate #Cutoff #Geometry #Gluon #Hadron #High-Energy Particle Collisions Research #Mathematics #Nonlinear system #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum electrodynamics #Quantum mechanics #Rapidity #Saturation (graph theory) #Scaling #Statistical physics #hep-ph

paper · pdf · doi:10.1103/physrevd.73.114003

published as Phys.Rev.D73:114003,2006 · 20 pages, LaTeX, 18 eps figures included using epsfig; changes in v3: new kind of averaging added, 5 new plots, discussions and conclusions extended, final version

arxiv created 2006/05/16 · openalex publication_date 2006/06/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We consider modifications of the standard nonlinear QCD evolution in an attempt to account for some of the missing ingredients discussed recently, such as correlations, discreteness in gluon emission and Pomeron loops. The evolution is numerically performed using the Balitsky-Kovchegov equation on individual configurations defined by a given initial value of the saturation scale, for reduced rapidities y=(\ensuremathα_sN_c/\ensuremathπ)Y<10. We consider the effects of averaging over configurations as a way to implement correlations, using three types of Gaussian averaging around a mean saturation scale. Further, we heuristically mimic discreteness in gluon emission by considering a modified evolution in which the tails of the gluon distributions are cut off. The approach to scaling and the behavior of the saturation scale with rapidity in these modified evolutions are studied and compared with the standard mean-field results. For the large but finite values of rapidity explored, no strong quantitative difference in scaling for transverse momenta around the saturation scale is observed. At larger transverse momenta, the influence of the modifications in the evolution seems most noticeable in the first steps of the evolution. No influence on the rapidity behavior of the saturation scale due to the averaging procedure is found. In the cutoff evolution the rapidity evolution of the saturation scale is slowed down and strongly depends on the value of the cutoff. Our results stress the need to go beyond simple modifications of evolution by developing proper theoretical tools that implement such recently discussed ingredients.

Citations

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• On the projectile-target duality of the color glass condensate in the dipole picture
• Saturation effects in deep inelastic scattering at lowQ2and its implications on diffraction
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