Study of proton parton distribution functions at high x

TL;DR

This paper compares various proton parton distribution functions at high x using ZEUS data, revealing significant discrepancies and proposing a method to incorporate this data into future PDF fits.

Contribution

It introduces a new technique for comparing PDF predictions with high-x ZEUS data and discusses how to include this data in future global PDF analyses.

Findings

Wide variation in PDF predictions at high x

ZEUS data can constrain PDFs at large x

Proposed scheme for incorporating high-x data

Abstract

At large values of $x$ the parton distribution functions (PDFs) of the proton are poorly constrained and there are considerable variations between different global fits. Data at such high $x$ have already been published by the ZEUS Collaboration, but not yet used in PDF extractions. A technique for comparing predictions based on different PDF sets to the observed number of events in the ZEUS data is presented. It is applied to compare predictions from the most commonly used PDFs to published ZEUS data at high Bjorken $x$. A wide variation is found in the ability of the PDFs to predict the observed results. A scheme for including the ZEUS high $x$ data in future PDF extractions is discussed.