Gluon Distributions and Color Charge Correlations in a Saturated Light-cone Wavefunction

TL;DR

The paper analyzes the saturated light-cone wavefunction of a high-energy hadron by expressing the gluon content through phase-space density, occupation number, and the color-charge correlator ρ. Starting from the MV model, it contrasts uncorrelated valence-quark sources with the color-shielded, correlated gluon field that emerges under BFKL evolution and saturation dynamics, notably via the Kovchegov equation. It derives general, robust results for the phase-space gluon density in saturation, showing dxG/d^2b d^2ℓ_perp ∝ (N_c^2−1)/(αN_c) ln[Q_s^2/ℓ_perp^2], and an explicit form for the color-charge correlator ρ(ℓ_perp,Y) that grows as ℓ_perp^2 ln(Q_s^2/ℓ_perp^2), reflecting strong shielding. The work extends to running coupling, where the same qualitative dependence holds with ⟨1/α⟩ replacing 1/α. A simple physical picture ties these results to the spatial and rapidity structure of gluon sources around the saturation boundary, providing an intuitive understanding of color shielding in saturated hadronic wavefunctions.

Abstract

We describe the light-cone wavefunction in the saturation regime in terms of the density of gluons per unit of transverse phase space, the occupation number, and in terms of the color charge correlator. The simple McLerran- Venugopalan model gives what are claimed to be general results for the phase space gluon density, but it does not well describe the general case for the charge correlator. We derive the general momentum dependence and rapidity dependence of the color charge correlator which exhibits strong color shielding. A simplel physical picture which leads to these general results is described.