https://doi.org/10.1140/epjc/s10052-021-09207-4
Regular Article - Theoretical Physics
Relativistic spin sum rules and the role of the pivot
CPHT, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91128, Palaiseau, France
a
cedric.lorce@polytechnique.edu
Received:
29
March
2021
Accepted:
2
May
2021
Published online:
11
May
2021
Spin sum rules depend on the choice of a pivot, i.e. the point about which the angular momentum is defined, usually identified with the center of the nucleon. The latter is however not unique in a relativistic theory and has led to apparently contradictory results in the literature. Using the recently developed phase-space approach, we compute for the first time the contribution associated with the motion of the center of the nucleon, and we derive a general spin sum rule which reduces to established results after appropriate choices for the pivot and the spin component.
© The Author(s) 2021
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