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Revisiting the gluon density from the Balitsky-Kovchegov equation with kinematical constraints and large x terms

Krzysztof Kutak1, Wanchen Li2,*, Anna Stasto3, and Robert Straka4

  • *Contact author: wanchenli@fudan.edu.cn
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Phys. Rev. D 111, 116021 – Published 24 June, 2025

DOI: https://doi.org/10.1103/rmt7-kl7s

Abstract

We perform analysis of the small x nonlinear evolution equation formulated in momentum space supplemented by higher order terms. The equation is defined in the wide range of transverse momentum and longitudinal momentum fractions extending previous studies performed in Kutak and Kwiecinski [Screening effects in the ultrahigh-energy neutrino interactions, Eur. Phys. J. C 29, 521 (2003).] and in Kutak and Stasto [Unintegrated gluon distribution from modified BK equation, Eur. Phys. J. C 41, 343 (2005).]. The linear part of the equation is motivated by the renormalization group improved small x approach, which accounts for resummation of higher orders, and includes collinear splitting functions and kinematical constraints. The solution to the equation is then used to perform the fit to deep inelastic scattering reduced cross section data.

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Phys. Rev. D 111, 116021– Published 24 June, 2025
  • Received 17 March 2025
  • Accepted 29 May 2025
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