Abstract
The total gluon helicity in a polarized proton, measurable in high-energy scattering, is shown to be the large momentum limit of a gauge-invariant but nonlocal, frame-dependent gluon spin in QCD. This opens a door for a nonperturbative calculation of this quantity in lattice QCD and also justifies using free-field expressions in the light-cone gauge as physical observables.
- Received 3 April 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.112002
© 2013 American Physical Society