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Title: Collinearly-improved BK evolution meets the HERA data

In a previous publication, we have established a collinearly-improved version of the Balitsky–Kovchegov (BK) equation, which resums to all orders the radiative corrections enhanced by large double transverse logarithms. Here, we study the relevance of this equation as a tool for phenomenology, by confronting it to the HERA data. To that aim, we first improve the perturbative accuracy of our resummation, by including two classes of single-logarithmic corrections: those generated by the first non-singular terms in the DGLAP splitting functions and those expressing the one-loop running of the QCD coupling. The equation thus obtained includes all the next-to-leading order corrections to the BK equation which are enhanced by (single or double) collinear logarithms. Furthermore, we then use numerical solutions to this equation to fit the HERA data for the electron–proton reduced cross-section at small Bjorken x. We obtain good quality fits for physically acceptable initial conditions. Our best fit, which shows a good stability up to virtualities as large as Q 2 = 400 GeV 2 for the exchanged photon, uses as an initial condition the running-coupling version of the McLerran–Venugopalan model, with the QCD coupling running according to the smallest dipole prescription.
 [1] ;  [1] ;  [2] ;  [1] ;  [3]
  1. Institut de Physique Theorique, Gif-sur-Yvette (France)
  2. Columbia Univ., New York, NY (United States)
  3. European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) and Fondazione Bruno Kessler, Villazzano (Italy)
Publication Date:
Grant/Contract Number:
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 750; Journal Issue: C; Journal ID: ISSN 0370-2693
Research Org:
Columbia Univ., New York, NY (United States)
Sponsoring Org:
Country of Publication:
United States
QCD; high-energy evolution; parton saturation; deep inelastic scattering
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1241900