# Neutron valence structure from nuclear deep inelastic scattering

## TL;DR

This paper extracts the neutron structure function from DIS data, accounting for nuclear effects, and finds the neutron-to-proton ratio approaches 0.47 at high x, aligning with QCD predictions.

## Contribution

It provides a novel extraction of the neutron structure function from global DIS data, incorporating nuclear modifications within a universal SRC framework.

## Key findings

- Neutron-to-proton structure function ratio approaches 0.47 at high x.
- Results agree with perturbative QCD and Dyson-Schwinger predictions.
- Provides predictions for $F_2^{^3He}/F_2^{^3H}$ and associated uncertainties.

## Abstract

Mechanisms of spin-flavor SU(6) symmetry breaking in Quantum Chromodynamics (QCD) are studied via an extraction of the free neutron structure function from a global analysis of deep inelastic scattering (DIS) data on the proton and on nuclei from $A = 2$ (deuterium) to 208 (lead). Modification of the structure function of nucleons bound in atomic nuclei (known as the EMC effect) are consistently accounted for within the framework of a universal modification of nucleons in short-range correlated (SRC) pairs. Our extracted neutron-to-proton structure function ratio $F_2^n/F_2^p$ becomes constant for $x_B \ge 0.6$, equalling $0.47 \pm 0.04$ as $x_B \rightarrow 1$, in agreement with theoretical predictions of perturbative QCD and the Dyson Schwinger equation, and in disagreement with predictions of the Scalar Diquark dominance model. We also predict $F_2^{^3\mathrm{He}}/F_2^{^3\mathrm{H}}$, recently measured, yet unpublished, by the MARATHON collaboration, the nuclear correction function that is needed to extract $F_2^n/F_2^p$ from $F_2^{^3\mathrm{He}}/F_2^{^3\mathrm{H}}$, and the theoretical uncertainty associated with this extraction.