Unbiased Polarised Parton Distribution Functions and their Uncertainties

TL;DR

This paper introduces a new method for determining spin-dependent polarized Parton Distribution Functions (PDFs) using the NNPDF approach, highlighting the importance of accurately estimating uncertainties, especially for the gluon distribution.

Contribution

It extends the NNPDF methodology to polarized PDFs, providing a more faithful and statistically sound estimation of uncertainties compared to previous methods.

Findings

Polarized PDF uncertainties are often underestimated in standard analyses.

The NNPDF approach offers a more reliable uncertainty estimation for polarized PDFs.

Significant uncertainties remain for the polarized gluon distribution.

Abstract

We present preliminary results on the determination of spin-dependent, or polarised, Parton Distribution Functions (PDFs) from all relevant inclusive polarised DIS data. The analysis is performed within the NNPDF approach, which provides a faithful and statistically sound representation of PDFs and their uncertainties. We describe how the NNPDF methodology has been extended to the polarised case, and compare our results with other recent polarised parton sets. We show that polarised PDF uncertainties can be sizeably underestimated in standard determinations, most notably for the gluon.