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arXiv · 1304.6708

Physics of Gluon Helicity Contribution to Proton Spin

Xiangdong Ji·Jian-Hui Zhang·Yong Zhao
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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 non-local, frame-dependent gluon spin $\vec{E}\times \vec{A}_\perp$ in QCD. This opens a door for a non-perturbative calculation of this quantity in lattice QCD, and also justifies using free-field expressions in the light-cone gauge as physical observables.

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Xiangdong Ji, Jian-Hui Zhang, Yong Zhao. 2013-04-24. Physics of Gluon Helicity Contribution to Proton Spin. https://doi.org/10.1103/physrevlett.111.112002

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