Deuterium scattering experiments in CTEQ global QCD analyses: a comparative investigation

TL;DR

This paper assesses how theoretical corrections for deuteron nuclear structure influence the determination of parton distribution functions in global QCD analyses, highlighting their importance for precise high-momentum physics.

Contribution

It introduces a comparative investigation of deuteron correction impacts on PDFs using the $L_2$ sensitivity method within CJ15 and CT18 analyses, revealing their significance for future precision measurements.

Findings

Deuteron corrections affect PDF uncertainties at high momentum fractions.

Inclusion of free deuteron corrections alters the flavor separation of quarks.

Compatibility of deuteron data with other experiments depends on correction implementation.

Abstract

Experimental measurements in deep-inelastic scattering and lepton-pair production on deuterium targets play an important role in the flavor separation of $u$ and $d$ (anti)quarks in global QCD analyses of the parton distribution functions (PDFs) of the nucleon. We investigate the impact of theoretical corrections accounting for the light-nuclear structure of the deuteron upon the fitted $u, d$-quark, gluon, and other PDFs in the CJ15 and CT18 families of next-to-leading order CTEQ global analyses. The investigation is done using the $L_2$ sensitivity statistical method, which provides a common metric to quantify the strength of experimental constraints on various PDFs and ratios of PDFs in the two distinct fitting frameworks. Using the $L_2$ sensitivity and other approaches, we examine the compatibility of deuteron data sets with other fitted experiments under varied implementations of the deuteron corrections. We find that freely-fitted deuteron corrections modify the PDF uncertainty at large momentum fractions and will be relevant for future PDFs affecting electroweak precision measurements.