A first unbiased global determination of polarized PDFs and their uncertainties

TL;DR

This paper provides the first unbiased global analysis of polarized parton distribution functions (PDFs) using comprehensive data, improving the understanding of spin structure of the proton and offering predictions for spin asymmetries in collider experiments.

Contribution

It introduces the NNPDFpol1.1 set, a novel polarized PDF determination incorporating diverse recent data, enabling more accurate separation of quark, antiquark, and gluon polarizations.

Findings

Enhanced polarized gluon PDF at medium and large x

Successful separation of quark and antiquark polarizations

Predictions for double-spin asymmetries at RHIC

Abstract

We present a first global determination of spin-dependent parton distribution functions (PDFs) and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the previous NNPDFpol1.0 PDF set, are supplemented with the most recent polarized hadron collider data for inclusive jet and $W$ boson production from the STAR and PHENIX experiments at RHIC, and with open-charm production data from the COMPASS experiment, thereby allowing for a separate determination of the polarized quark and anti-quark PDFs, and an improved determination of the medium- and large-$x$ polarized gluon PDF. We study the phenomenological implications of the NNPDFpol1.1 set, and we provide predictions for the longitudinal double-spin asymmetry for semi-inclusive pion production at RHIC.