CGC and saturation approach: Impact-parameter dependent model of perturbative QCD and combined HERA data

Abstract

In this paper we confront the CGC/saturation approach of Ref.~\cite{CLMS} with the experimental combined HERA data and obtain its parameters. The model includes two features that are in accordance with our theoretical knowledge of deep inelastic scattering. These consist of: \textit{i}) the use of analytical solution for the non-linear Balitsky-Kovchegov (BK) evolution equation and \textit{ii}) the exponential behavior of the saturation momentum on the impact parameter $b$-dependence, characterized by $Q_s$ $\propto \exp (-mb)$ which reproduces the correct behavior of the scattering amplitude at large $b$ in accord with Froissart theorem. The model results are then compared to data at small-$x$ for the structure-function of the proton $F_2$, the longitudinal structure function $F_L$, the charm structure function $F_2^{c\bar{c}}$, the exclusive vector meson ($J/\psi ,\varphi ,\rho$) production and Deeply Virtual Compton Scattering (DVCS). We obtain a good agreement for the processes in a wide kinematic range of $Q^2$ at small-$x$. Our results provide a strong guide for finding an approach, based on Color Glass Condensate/saturation effective theory for high energy QCD, to make reliable predictions from first principles and for forthcoming experiments like the Electron-Ion Collider and the LHeC.

22 pages, 14 figures, 3 tables

References in corpus (21)

• NLO evolution of color dipoles
• Quark contribution to the small-$x$ evolution of color dipole
• Triumvirate of Running Couplings in Small-x Evolution
• Analysis of combined HERA data in the Impact-Parameter dependent Saturation model
• Impact parameter dependent colour glass condensate dipole model
• Nuclear enhancement and suppression of diffractive structure functions at high energies
• Exclusive diffractive processes in electron-ion collisions
• Non-linear evolution in QCD at high-energy beyond leading order
• CGC predictions for p+A collisions at the LHC and signature of QCD saturation
• Gluon saturation and inclusive hadron production at LHC
• Saturation and Scaling of Multiplicity, Mean p_T and p_T Distributions from 200 GeV < sqrt{s} < 7 TeV - Addendum
• NLO JIMWLK evolution unabridged
• Hadron multiplicity in pp and AA collisions at LHC from the Color Glass Condensate
• Gluon saturation and energy dependence of hadron multiplicity in pp and AA collisions at the LHC
• Deep inelastic cross-section measurements at large y with the ZEUS detector at HERA
• Investigating saturation effects in ultraperipheral collisions at the LHC with the color dipole model
• Geometrical scaling in hadronic collisions
• CGC/saturation approach: a new impact-parameter dependent model in the next-to-leading order of perturbative QCD
• Rare fluctuations of the $S$-matrix at NLO in QCD
• Non-linear evolution in the re-summed next-to-leading order of perturbative QCD:\confronting the experimental data
• Soft Pomeron in the Colour Glass Condensate approach

Cited by in corpus (1)

• Testing the double-logarithm asymptotic gluon density in ultraperipheral heavy ion collisions at the Large Hadron Collider