Detailed Study of Quark-Hadron Duality in Spin Structure Functions of the Proton and Neutron

TL;DR

This study investigates quark-hadron duality in the spin structure functions of protons and neutrons, demonstrating a transition to duality at certain energy scales and analyzing the scaling behavior at high momentum transfer.

Contribution

It provides the first detailed comparison between extrapolated DIS data and resonance region measurements for spin structure functions, highlighting the conditions for quark-hadron duality.

Findings

Clear transition to quark-hadron duality observed

Scaling behavior of g1 measured at high Q^2

Quantifies deviations from pQCD at moderate energies

Abstract

In this paper, we present for the first time comprehensive and detailed results on the correspondence between the extrapolated deep inelastic structure function $g_1$ of both the proton and the neutron with the same quantity measured in the nucleon resonance region. We use a QCD parameterization of the world data on DIS spin structure functions, extrapolated into the nucleon resonance region and averaged over various intervals in the scaling variable $x$. We compare the results with the large data set collected in the quark-hadron transition region by the CLAS collaboration, averaged over the same intervals. We present this comparison as a function of the momentum transfer $Q^2$. We find that, depending on the averaging interval and the minimum momentum transfer chosen, a clear transition to quark-hadron duality can be observed in both nucleon species. Furthermore, we show, for the first time, the scaling behavior of $g_1$ measured in the resonance region at sufficiently high momentum transfer. Our results can be used to quantify the deviations from the applicability of pQCD for data taken at moderate energies, and help with extraction of quark distribution functions from such data.