Determination of the theory uncertainties from missing higher orders on NNLO parton distributions with percent accuracy

TL;DR

This paper quantifies the impact of missing higher order QCD corrections on parton distribution functions, demonstrating that including these uncertainties improves the consistency and reduces the uncertainties in the NNPDF4.0 PDFs at NNLO.

Contribution

It introduces a methodology to incorporate missing higher order uncertainties into PDF determinations, enhancing the accuracy and consistency of the NNPDF4.0 set.

Findings

Inclusion of MHOUs leads to more consistent PDFs.

Incorporating MHOUs reduces PDF uncertainties.

Method improves the reliability of NNLO PDFs.

Abstract

We include uncertainties due to missing higher order corrections to QCD computations (MHOU) used in the determination of parton distributions (PDFs) in the recent NNPDF4.0 set of PDFs. We use our previously published methodology, based on the treatment of MHOUs and their full correlations through a theory covariance matrix determined by scale variation, now fully incorporated in the new NNPDF theory pipeline. We assess the impact of the inclusion of MHOUs on the NNPDF4.0 central values and uncertainties, and specifically show that they lead to improved consistency of the PDF determination with an ensuing moderate reduction of PDF uncertainties at NNLO.