Analysis of combined HERA data in the Impact-Parameter dependent Saturation model

Abstract

The Impact-Parameter dependent Saturation Model (IP-Sat) is a simple dipole model that incorporates key features of the physics of gluon saturation and matches smoothly to the perturbative QCD dipole expression at large Q^2 for a given x. It was previously shown that the model gives a good description of HERA data suggesting evidence for gluon saturation effects at small x. The model has also been applied to proton-proton and proton-nucleus collisions and provides the basis for the IP-Glasma model of initial conditions in heavy ion collisions. Here we present a reanalysis of available data in electron-proton collisions at small Bjorken-x, including the recently released combined data from the ZEUS and H1 collaborations. We first confront the model to the high precision combined data for the reduced cross-section and obtain its parameters. With these parameters fixed, we compare model results to data for the structure function F_2, the longitudinal structure function F_L, the charm structure function F_2^{c\bar{c}}, exclusive vector meson (J/ψ, ϕand ρ) production and Deeply Virtual Compton Scattering (DVCS). Excellent agreement is obtained for the processes considered at small x in a wide range of Q^2. Our results strongly hint at universality of the IP-Sat dipole amplitude and the extracted impact-parameter distribution of the proton. They also provide a benchmark for further refinements in studies of QCD saturation at colliders.

17 pages, 18 figures

References in corpus (12)

• New parton distributions for collider physics
• The Color Glass Condensate
• Quark contribution to the small-$x$ evolution of color dipole
• Event-by-event gluon multiplicity, energy density and eccentricities at RHIC and LHC
• Impact parameter dependent colour glass condensate dipole model
• Heavy-quark mass dependence in global PDF analyses and 3- and 4-flavour parton distributions
• Saturation QCD predictions with heavy quarks at HERA
• Nuclear enhancement and suppression of diffractive structure functions at high energies
• CGC predictions for p+A collisions at the LHC and signature of QCD saturation
• Gluon saturation and inclusive hadron production at LHC
• Gluon saturation and energy dependence of hadron multiplicity in pp and AA collisions at the LHC
• Hadron multiplicity in pp and AA collisions at LHC from the Color Glass Condensate

Cited by in corpus (10)

• Eccentric protons? Sensitivity of flow to system size and shape in p+p, p+Pb and Pb+Pb collisions
• J/Psi production in ultraperipheral Pb+Pb and p+Pb collisions at energies available at the CERN Large Hadron Collider
• Forward $J/\psi$ production in proton-nucleus collisions at high energy
• Ballistic protons in incoherent exclusive vector meson production as a measure of rare parton fluctuations at an Electron-Ion Collider
• Diphoton production in high-energy p+A collisions
• Nuclear effects in neutrinoproduction of pions
• Scattering off the Color Glass Condensate
• Diffractive vector meson production in ultraperipheral heavy ion collisions from the Color Glass Condensate
• b-CGC versus IP-Sat and high precision combined HERA data
• Diffractive photoproduction of vector mesons at the LHC