Parton distributions at low x and gluon- and quark average multiplicities

TL;DR

This paper presents a diagonalization-based approach for Q2 evolution of parton densities and fragmentation functions at low x, incorporating nonperturbative parameters fitted to experimental data, improving agreement with observations.

Contribution

It introduces a novel diagonalization method for Q2 evolution at low x, accounting for two components with nonperturbative parameters fitted to data.

Findings

The approach effectively describes the small x behavior of parton distributions.

Including both components improves fit to experimental data.

The method captures large logarithms ln(1/x) in the evolution.

Abstract

We shown the general approach for Q2 evolution of parton densities and fragmentation functions at low x based on the diagonalization. The diagonalization leads to the two components in the Q2 evolution, each of which contains a nonperturbative parameter. The values of the parameters can be found by fits of the experimental data for the deep-inelastic scattering structure function F2 and for average jet multiplicities. One of the components contains the all large logarithms ln(1/x) and produce the basic contribution at small x region. The second one is regular at low x but its contribution is very important to have a good agreement with experimental data