DIS and the effects of fluctuations: a momentum space analysis

• Published in: The European physical journal. C, Particles and fields Vol. 58; no. 1; pp. 9 - 15
• Main Authors: Basso, E., Gay Ducati, M. B., de Oliveira, E. G., de Santana Amaral, J. T.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.11.2008; Springer; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Cosmology; Dipoles; Elementary Particles; Exact sciences and technology; Forward scattering; Gluons; Hadrons; Heavy Ions; Inelastic scattering; Measurement Science and Instrumentation; Momentum; Nuclear Energy; Nuclear Physics; Physics; Physics and Astronomy; Protons; Quantum Field Theories; Quantum Field Theory; Regular Article - Theoretical Physics; Scattering amplitude; String Theory; The physics of elementary particles and fields; Traveling waves; Variation; Saturation Scale; HERA Data; BFKL Equation; Deep Inelastic Scattering; ZEUS Collaboration; Protons; Mean field approximation; Fluctuations; Electron-proton scattering; Dipoles; Saturation; Structure functions; Scattering amplitudes; Travelling waves; Forward scattering; Inelastic scattering; Gluons; Momentum space; Elementary particles; Models; Virtual particles; Cross sections; Mathematical physics; Quantum chromodynamics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-008-0730-3

Among the dipole models of deep inelastic scattering at small values of the Bjorken variable x , one has been recently proposed which relates the virtual photon–proton cross section to the dipole–proton forward scattering amplitude in momentum space. The latter is parametrized by an expression which interpolates between its behavior at saturation and the travelling wave, ultraviolet, amplitudes predicted by perturbative QCD from the Balitsky–Kovchegov equation. Inspired by recent developments in coordinate space, we use this model to parametrize the structure function of the proton and confront it with HERA data on ep deep inelastic scattering. Both event-by-event and physical amplitudes are considered, the latter being used to investigate the effect of gluon number fluctuations, beyond the mean-field approximation. We conclude that fluctuations are not present in DIS at HERA energies.