Collinearlyimproved BK evolution meets the HERA data
In a previous publication, we have established a collinearlyimproved 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 singlelogarithmic corrections: those generated by the first nonsingular terms in the DGLAP splitting functions and those expressing the oneloop running of the QCD coupling. The equation thus obtained includes all the nexttoleading 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 crosssection 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 runningcoupling version of the McLerran–Venugopalan model, with the QCD coupling running according to the smallest dipole prescription.
 Authors:

^{[1]};
^{[1]};
^{[2]};
^{[1]};
^{[3]}
 Institut de Physique Theorique, GifsurYvette (France)
 Columbia Univ., New York, NY (United States)
 European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) and Fondazione Bruno Kessler, Villazzano (Italy)
 Publication Date:
 Grant/Contract Number:
 FG0292ER40699
 Type:
 Published Article
 Journal Name:
 Physics Letters. Section B
 Additional Journal Information:
 Journal Volume: 750; Journal Issue: C; Journal ID: ISSN 03702693
 Publisher:
 Elsevier
 Research Org:
 Columbia Univ., New York, NY (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 QCD; highenergy evolution; parton saturation; deep inelastic scattering
 OSTI Identifier:
 1223822
 Alternate Identifier(s):
 OSTI ID: 1241900
Iancu, E., Madrigal, J. D., Mueller, A. H., Soyez, G., and Triantafyllopoulos, D. N.. Collinearlyimproved BK evolution meets the HERA data. United States: N. p.,
Web. doi:10.1016/j.physletb.2015.09.071.
Iancu, E., Madrigal, J. D., Mueller, A. H., Soyez, G., & Triantafyllopoulos, D. N.. Collinearlyimproved BK evolution meets the HERA data. United States. doi:10.1016/j.physletb.2015.09.071.
Iancu, E., Madrigal, J. D., Mueller, A. H., Soyez, G., and Triantafyllopoulos, D. N.. 2015.
"Collinearlyimproved BK evolution meets the HERA data". United States.
doi:10.1016/j.physletb.2015.09.071.
@article{osti_1223822,
title = {Collinearlyimproved BK evolution meets the HERA data},
author = {Iancu, E. and Madrigal, J. D. and Mueller, A. H. and Soyez, G. and Triantafyllopoulos, D. N.},
abstractNote = {In a previous publication, we have established a collinearlyimproved 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 singlelogarithmic corrections: those generated by the first nonsingular terms in the DGLAP splitting functions and those expressing the oneloop running of the QCD coupling. The equation thus obtained includes all the nexttoleading 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 crosssection 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 Q2 = 400 GeV2 for the exchanged photon, uses as an initial condition the runningcoupling version of the McLerran–Venugopalan model, with the QCD coupling running according to the smallest dipole prescription.},
doi = {10.1016/j.physletb.2015.09.071},
journal = {Physics Letters. Section B},
number = C,
volume = 750,
place = {United States},
year = {2015},
month = {10}
}