Gluon distributions from Oliveira-Martin-Ryskin combined BFKL+DGLAP evolution equations

TL;DR

This paper numerically investigates combined BFKL+DGLAP evolution equations for gluon distributions, demonstrating the feasibility of using the opening angle as a natural evolution variable and comparing different subtraction methods.

Contribution

It introduces a numerical study of combined BFKL+DGLAP equations reformulated with the opening angle as the evolution variable, validating its effectiveness and comparing subtraction schemes.

Findings

The opening angle { heta} is a more natural evolution variable.

Numerical tests confirm the feasibility of the new approach.

Different subtraction methods are compared and analyzed.

Abstract

Kwiecinski, Martin, Stasto [13] argue for inclusion of DGLAP terms into BFKL evolution of unintegrated gluon density. The equation was reformulated by Oliveira, Martin, Ryskin [6] employing the opening angle {\theta} = k/xp as the evolution variable. It leads to a description of a {\theta}-integrated gluon density. This paper is a numerical study of these two similar combined BFKL+DGLAP formulations. It is a demonstration of feasibility of the new approach. The different ways of subtracting the contribution common for BFKL and DGLAP proposed in [13] and [6] are compared. The numerical tests confirm that the {\theta} variable is a more natural evolution variable for this kind of equation.