Next generation proton PDFs with deuteron and nuclear uncertainties

TL;DR

This paper introduces NNPDF4.0, a new set of proton PDFs that incorporate nuclear and deuteron uncertainties, improving the accuracy of global PDF fits with more precise data.

Contribution

It presents a novel method to include nuclear and deuteron uncertainties in global proton PDF determinations, enhancing the reliability of the PDFs.

Findings

Nuclear uncertainties are significant in global PDF fits.

The iterative procedure effectively determines proton and deuteron PDFs simultaneously.

Accounting for nuclear uncertainties resolves tensions in the fit.

Abstract

As data become more precise, estimating theoretical uncertainties in global PDF determinations is likely to become increasingly necessary to obtain correspondingly precise PDFs. Here we present a next generation of global proton PDFs (NNPDF4.0) that include theoretical uncertainties due to the use of heavy nuclear and deuteron data in the fit. We estimate these uncertainties by comparing the values of the nuclear observables computed with the nuclear PDFs against those computed with proton PDFs. For heavy nuclear PDFs we use the nuclear nNNPDF2.0 set, while for deuteron PDFs we develop an iterative procedure to determine proton and deuteron PDFs simultaneously, each including the uncertainties in the other. Accounting for nuclear uncertainties resolves some of the tensions in the global fit of the proton PDFs, especially those between the nuclear data and the extended LHC data set used in NNPDF4.0.