Why there is no crisis of the "spin crisis"

TL;DR

This paper refutes recent claims that the so-called 'spin crisis' is invalid, defending the original interpretation of experimental data and clarifying that previous theoretical understanding remains valid, especially for the Compass data.

Contribution

It provides a rebuttal to recent reanalyses claiming the spin crisis is invalid, reaffirming the validity of earlier experimental and theoretical conclusions.

Findings

The original spin crisis interpretation remains valid for Compass data.

Recent reanalyses do not apply to all experimental data.

Theoretical understanding of nucleon spin contributions is upheld.

Abstract

In a recent eprint [1] it is argued that the experimental determinations of the spin-dependent structure function g1 have been done incorrectly and that a reanalysis of those data suggests that the original motivation to argue fora "spin crisis", namely the small contribution of quark spins to the nucleon spin, is invalid. In a subsequent note [2] the theoretical understanding, as it has evolved from almost 30 years of theoretical and experimental scrutiny, has been shortly summarised. In this short note, arguments are presented that the line of reasoning in Ref. [1] does not apply, at least not for the Compass data.