Proton Spin in Deep Inelastic Scattering

TL;DR

This paper extends the analysis of polarized proton and neutron structure functions to their x dependence, finding good agreement with static quark model predictions at high x and evidence of quark fragmentation at low x.

Contribution

It introduces an x-dependent analysis of polarized structure functions, revealing different scattering regimes and polarization effects in deep inelastic scattering.

Findings

Excellent agreement with static quark model for x>0.2

Rapid drop of structure function for x<0.2

Evidence of quark fragmentation affecting polarization

Abstract

So far the analyses of the polarized structure functions of the proton and neutron have been limited to the evaluation of their integrals and comparing them to the prediction of the static quark model of the nucleon. We extended our analysis to the x dependence of the polarized structure functions and observe: the measured structure function excellently agrees with the prediction of the static quark model for Bjorken $x>0.2$ and drops rapidly for $x<0.2$. It is suggested that for Bjorken $x>0.2$ electrons get scattered on the undamaged constituent quarks (alias valence quarks) denoted as quasi-elastic scattering on the constituent quarks and for $x<0.2$ the constituent quarks fragment. In the fragmentation strong interaction is involved which does not preserve the polarization.