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Title: Nonlinear QCD meets data: A global analysis of lepton-proton scattering with running coupling Balitsky-Kovchegov evolution

Abstract

We perform a global fit to the structure function F{sub 2} measured in lepton-proton experiments at small values of Bjorken-x, x{<=}0.01, for all experimentally available values of Q{sup 2}, 0.045 GeV{sup 2}{<=}Q{sup 2}{<=}800 GeV{sup 2}. We show that the recent improvements resulting from the inclusion of running coupling corrections allow for a description of data in terms of nonlinear QCD evolution equations. In this approach F{sub 2} is calculated within the dipole model with all Bjorken-x dependence described by the running coupling Balitsky-Kovchegov equation. Two different initial conditions for the evolution are used, both yielding good fits to data with {chi}{sup 2}/d.o.f.<1.1. The proton longitudinal structure function F{sub L}, not included in the fits, is also well described. Our analysis allows to perform a first principle extrapolation of the proton-dipole scattering amplitude once the initial condition has been fitted to presently available data. We provide predictions for F{sub 2} and F{sub L} in the kinematical regions of interest for future colliders and ultra-high energy cosmic rays. A numerical implementation of our results down to x=10{sup -12} is released as a computer code for public use.

Authors:
 [1]; ;  [2];  [3]
  1. European Center for Theoretical Studies in Nuclear Physics and Related Areas (ECT), Strada delle Tabarelle 286, I-38050 Villazzano (Italy)
  2. Departamento de Fisica de Particulas and IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain)
  3. CENTRA, Instituto Superior Tecnico (IST), Avenida Rovisco Pais, P-1049-001 Lisboa (Portugal)
Publication Date:
OSTI Identifier:
21322360
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 80; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevD.80.034031; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COMPUTERIZED SIMULATION; CORRECTIONS; COSMIC RADIATION; COUPLING; DIPOLES; EQUATIONS; EXTRAPOLATION; FORECASTING; GLOBAL ANALYSIS; LEPTON-PROTON INTERACTIONS; LEPTONS; NONLINEAR PROBLEMS; PROTONS; QUANTUM CHROMODYNAMICS; SCATTERING AMPLITUDES; STRUCTURE FUNCTIONS

Citation Formats

Albacete, Javier L, Armesto, Nestor, Salgado, Carlos A, and Milhano, Jose Guilherme. Nonlinear QCD meets data: A global analysis of lepton-proton scattering with running coupling Balitsky-Kovchegov evolution. United States: N. p., 2009. Web. doi:10.1103/PHYSREVD.80.034031.
Albacete, Javier L, Armesto, Nestor, Salgado, Carlos A, & Milhano, Jose Guilherme. Nonlinear QCD meets data: A global analysis of lepton-proton scattering with running coupling Balitsky-Kovchegov evolution. United States. doi:10.1103/PHYSREVD.80.034031.
Albacete, Javier L, Armesto, Nestor, Salgado, Carlos A, and Milhano, Jose Guilherme. Sat . "Nonlinear QCD meets data: A global analysis of lepton-proton scattering with running coupling Balitsky-Kovchegov evolution". United States. doi:10.1103/PHYSREVD.80.034031.
@article{osti_21322360,
title = {Nonlinear QCD meets data: A global analysis of lepton-proton scattering with running coupling Balitsky-Kovchegov evolution},
author = {Albacete, Javier L and Armesto, Nestor and Salgado, Carlos A and Milhano, Jose Guilherme},
abstractNote = {We perform a global fit to the structure function F{sub 2} measured in lepton-proton experiments at small values of Bjorken-x, x{<=}0.01, for all experimentally available values of Q{sup 2}, 0.045 GeV{sup 2}{<=}Q{sup 2}{<=}800 GeV{sup 2}. We show that the recent improvements resulting from the inclusion of running coupling corrections allow for a description of data in terms of nonlinear QCD evolution equations. In this approach F{sub 2} is calculated within the dipole model with all Bjorken-x dependence described by the running coupling Balitsky-Kovchegov equation. Two different initial conditions for the evolution are used, both yielding good fits to data with {chi}{sup 2}/d.o.f.<1.1. The proton longitudinal structure function F{sub L}, not included in the fits, is also well described. Our analysis allows to perform a first principle extrapolation of the proton-dipole scattering amplitude once the initial condition has been fitted to presently available data. We provide predictions for F{sub 2} and F{sub L} in the kinematical regions of interest for future colliders and ultra-high energy cosmic rays. A numerical implementation of our results down to x=10{sup -12} is released as a computer code for public use.},
doi = {10.1103/PHYSREVD.80.034031},
journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 3,
volume = 80,
place = {United States},
year = {2009},
month = {8}
}