2017/04/30 by Adrian Dumitru, Vladimir V. Skokov, Vladimir Skokov · 1 citation
Mathematics · Physics and Astronomy · #Action (physics) #Distribution (mathematics) #Environmental science #Gluon #High-Energy Particle Collisions Research #Mathematical analysis #Mathematics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum mechanics #Statistical physics #hep-ph
paper · pdf · doi:10.1103/physrevd.96.056029
published as Phys. Rev. D 96, 056029 (2017) · 14 pages, 5 figures; v2: added section IV-A to discuss the parametric dependence of the selected fluctuations on the number of colors and on the thickness of the target; v3: version accepted to Phys. Rev. D
openalex publication_date 2017/09/29 · arxiv created 2017/10/11 · arxiv updated 2017/10/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The computation of observables in high-energy QCD involves an average over stochastic semiclassical small-x gluon fields. The weight of various configurations is determined by the effective action. We introduce a method to study fluctuations of observables, functionals of the small-x fields, which does not explicitly involve dipoles. We integrate out those fluctuations of the semiclassical gluon field under which a given observable is invariant. Thereby we obtain the effective potential for that observable describing its fluctuations about the average. We determine explicitly the effective potential for the covariant gauge gluon distribution both for the McLerran-Venugopalan (MV) model and for a (nonlocal) Gaussian approximation for the small-x effective action. This provides insight into the correlation of fluctuations of the number of hard gluons versus their typical transverse momentum. We find that the spectral shape of the fluctuations of the gluon distribution is fundamentally different in the MV model, where there is a pileup of gluons near the saturation scale, versus the solution of the small-x JIMWLK renormalization group, which generates essentially scale-invariant fluctuations above the absorptive boundary set by the saturation scale.