More on the relation between the two physically inequivalent decompositions of the nucleon spin

Abstract

The recent controversy on the nucleon spin decomposition problem is critically overviewed. We argue that there exist two and only two physically inequivalent gauge-invariant decompositions of the longitudinal nucleon spin, contrary to the rapidly spreading view in the QCD spin physics community that there are infinitely many decompositions of the nucleon spin.

Comments: Invited Talk at the Third Workshop on the QCD Structure of the Nucleon (QCD N'12), Bilbao, Spain, 22-26 October 2012