Relativistic decomposition of the orbital and the spin angular momentum in chiral physics and Feynman's angular momentum paradox

Understand

Over recent years we have witnessed tremendous progresses in our understanding on the angular momentum decomposition.

• In the context of the proton spin problem in high energy processes the angular momentum decomposition by Jaffe and Manohar, which is based on the canonical definition, and the alternative by Ji, which is based on the Belinfante improved one, have been revisited under light shed by Chen et al.
• leading to seminal works by Hatta, Wakamatsu, Leader, etc.
• In chiral physics as exemplified by the chiral vortical effect and applications to the relativistic nucleus-nucleus collisions, sometimes referred to as a relativistic extension of the Barnett and the Einstein--de Haas effects, such arguments of the angular momentum decomposition would be of crucial importance.