Revisiting gluon density from the BK equation with kinematical constraint and large x terms

TL;DR

This paper revisits the gluon density at small x using a non-linear evolution equation in momentum space, incorporating higher order terms, kinematical constraints, and large x effects, to improve fits to DIS data.

Contribution

It introduces an extended small x evolution equation with higher order corrections and kinematical constraints, enhancing previous models and fitting DIS data more accurately.

Findings

Improved gluon density modeling at small x.

Better fit to Deep Inelastic Scattering data.

Inclusion of large x terms and higher order corrections.

Abstract

We perform analysis of the small x non-linear evolution equation formulated in momentum space supplemented by higher order terms. The equation is defined in wide range of transverse momentum and longitudinal momentum fraction extending previous studies performed in \cite{Kutak:2003bd,Kutak:2004ym}. 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 function and kinematical constraint. The solution to the equation is then used to perform the fit to Deep Inelastic Scattering reduced cross section data.