New Measurements of the Deuteron to Proton F2 Structure Function Ratio

TL;DR

This paper presents high-precision measurements of the deuteron to proton structure function ratio at large Bjorken-x, improving data accuracy and aiding the extraction of neutron and d-quark distributions in nucleons.

Contribution

It provides new, more precise data on the deuteron to proton ratio, reducing nuclear correction uncertainties and enhancing the extraction of d-quark parton distribution functions.

Findings

Significantly improved the precision of the deuteron to proton ratio data.

First look at the impact of new data on global quark distribution fits.

Supports better understanding of neutron structure and d-quark distributions.

Abstract

Nucleon structure functions, as measured in lepton-nucleon scattering, have historically provided a critical observable in the study of partonic dynamics within the nucleon. However, at very large parton momenta it is both experimentally and theoretically challenging to extract parton distributions due to the probable onset of non-perturbative contributions and the unavailability of high precision data at critical kinematics. Extraction of the neutron structure and the d-quark distribution have been further challenging due to the necessity of applying nuclear corrections when utilizing scattering data from a deuteron target to extract free neutron structure. However, a program of experiments has been carried out recently at the energy-upgraded Jefferson Lab electron accelerator aimed at significantly reducing the nuclear correction uncertainties on the d-quark distribution function at large partonic momentum. This allows leveraging the vast body of deuterium data covering a large kinematic range to be utilized for d-quark parton distribution function extraction. We present new data from experiment E12-10-002 carried out in Jefferson Lab Hall C on the deuteron to proton cross-section ratio at large BJorken-x. These results significantly improve the precision of existing data, and provide a first look at the expected impact on quark distributions extracted from global parton distribution function fits.