Measurements of Non-Singlet Moments of the Nucleon Structure Functions and Comparison to Predictions from Lattice QCD for $Q^2 = 4$ $\rm GeV^2$

TL;DR

This paper reports precise measurements of nucleon non-singlet moments using Jefferson Lab data, compares them with advanced Lattice QCD predictions at physical pion mass, and improves understanding of nucleon structure.

Contribution

It provides the first high-precision experimental non-singlet moments corrected for nuclear effects and compares them with state-of-the-art Lattice QCD calculations at physical pion mass.

Findings

Experimental moments are an order of magnitude more precise than previous results.

New data cover the crucial high-x region for moment determination.

Comparison shows good agreement with recent Lattice QCD predictions.

Abstract

We present extractions of the nucleon non-singlet moments utilizing new precision data on the deuteron $F_2$ structure function at large Bjorken-$x$ determined via the Rosenbluth separation technique at Jefferson Lab Experimental Hall C. These new data are combined with a complementary set of data on the proton previously measured in Hall C at similar kinematics and world data sets on the proton and deuteron at lower $x$ measured at SLAC and CERN. The new Jefferson Lab data provide coverage of the upper third of the $x$ range, crucial for precision determination of the higher moments. In contrast to previous extractions, these moments have been corrected for nuclear effects in the deuteron using a new global fit to the deuteron and proton data. The obtained experimental moments represent an order of magnitude improvement in precision over previous extractions using high $x$ data. Moreover, recent exciting developments in Lattice QCD calculations provide a first ever comparison of these new experimental results with calculations of moments carried out at the physical pion mass, as well as a new approach which first calculates the quark distributions directly before determining moments.