Global Analysis of Helicity Parton Densities and Their Uncertainties

TL;DR

This paper provides a comprehensive NLO QCD analysis of helicity parton distributions, incorporating diverse experimental data to reveal small gluon polarization and flavor asymmetries in the nucleon's spin structure.

Contribution

It introduces a fully NLO computational method for analyzing helicity PDFs using multiple data sources, enhancing precision and efficiency.

Findings

Evidence for small gluon polarization in the nucleon

Identification of flavor asymmetries in the polarized sea

First NLO analysis incorporating all relevant data efficiently

Abstract

We present a new analysis of the helicity parton distributions of the nucleon. The analysis takes into account the available data from inclusive and semi-inclusive polarized deep inelastic scattering, as well as from polarized pp scattering at RHIC. For the first time, all theoretical calculations are performed fully at next-to-leading order (NLO) of perturbative QCD, using a method that allows to incorporate the NLO corrections in a very fast and efficient way in the analysis. We find evidence for a rather small gluon polarization in the nucleon, over a limited region of momentum fraction, and for interesting flavor patterns in the polarized sea.