Uncertainties in determining parton distributions at large x

TL;DR

This paper analyzes uncertainties in large-x parton distribution functions caused by nuclear effects in deuterium data, highlighting their impact on neutron structure and collider processes, and discusses future measurement prospects.

Contribution

It provides a comprehensive assessment of nuclear model uncertainties in PDFs at large x and their effects on collider phenomenology.

Findings

Significant variation in d-quark and gluon PDFs due to nuclear model choices.

Uncertainties affect neutron structure function and W boson production predictions.

Discussion of future measurements to reduce nuclear correction uncertainties.

Abstract

We critically examine uncertainties in parton distribution functions (PDFs) at large x arising from nuclear effects in deuterium F2 structure function data. Within a global PDF analysis, we assess the impact on the PDFs from uncertainties in the deuteron wave function at short distances and nucleon off-shell effects, the use of relativistic kinematics, as well as the use of less a restrictive parametrization of the d/u ratio. We find that in particular the d-quark and gluon PDFs vary significantly with the choice of nuclear model. We highlight the impact of these uncertainties on the determination of the neutron structure function, and on W boson production and parton luminosity at the Tevatron and the LHC. Finally, we discuss prospects for new measurements sensitive to the d-quark and gluon distributions but insensitive to nuclear corrections.