The end of the nucleon-spin crisis

TL;DR

This paper argues that the perceived small quark polarization in nucleons from deep inelastic scattering is due to incorrect assumptions about polarized photon flux, and correcting this resolves the nucleon-spin crisis.

Contribution

It reveals that the flux of polarized virtual photons is overestimated, leading to a larger true quark polarization consistent with sum rules, thus ending the nucleon-spin crisis.

Findings

Corrected photon flux increases quark polarization estimates.

Quark polarization aligns with Ellis-Jaffe sum rule predictions.

Resolves the discrepancy with the Bjorken sum rule.

Abstract

The small fraction of the quark polarization of the nucleon obtained in deep inelastic lepton scattering is a consequence of a wrong assumption on the flux of polarized virtual photons in the analysis of the data. The true flux of polarized photons is due to fluctuations into strongly interacting quark-antiquarks at least 20\% smaller than assumed and, therefore, the quark polarization is larger. Realizing this peculiarity the quark polarization agrees with that given by the Ellis-Jaffe sum rule, i.e. is consistent with the prediction derived from the experimentally determined weak coupling constants. It also solves the problem with the under-exhaustion of the fundamental Bjorken-sum rule. However, it has to be realized that the fluctuations render it impossible to measure the quark spin with credibility.