Resumming large higher-order corrections in non-linear QCD evolution

TL;DR

This paper develops a resummation method for large higher-order corrections in non-linear QCD evolution equations, leading to stable solutions that fit experimental data at small-x.

Contribution

It introduces a collinearly improved BK equation that resums double and single logarithms, enhancing convergence and stability in high-energy QCD evolution.

Findings

Stable solutions to the improved BK equation

Successful fit to HERA small-x data

Enhanced convergence in non-linear QCD evolution

Abstract

Linear and non-linear QCD evolutions at high energy suffer from severe issues related to convergence, due to higher order corrections enhanced by large double and single transverse logarithms. We resum double logarithms to all orders by taking into account successive soft gluon emissions strongly ordered in lifetime. We further resum single logarithms generated by the first non-singular part of the splitting functions and by the one-loop running of the coupling. The resulting collinearly improved BK equation admits stable solutions, which are used to successfully fit the HERA data at small-x for physically acceptable initial conditions and reasonable values of the fit parameters.