6,364 research outputs found
One-Loop Matching for Parton Distributions: Non-Singlet Case
We derive one-loop matching condition for non-singlet quark distributions in
transverse-momentum cut-off scheme, including unpolarized, helicity and
transversity distributions. The matching is between the quasi-distribution
defined by static correlation at finite nucleon momentum and the light-cone
distribution measurable in experiments. The result is useful for extracting the
latter from the former in a lattice QCD calculation.Comment: 10 pages, 1 figur
Spin Decomposition of Electron in QED
We perform a systematic study on the spin decomposition of an electron in QED
at one-loop order. It is found that the electron orbital angular momentum
defined in Jaffe-Manohar and Ji spin sum rules agrees with each other, and the
so-called potential angular momentum vanishes at this order. The calculations
are performed in both dimensional regularization and Pauli-Villars
regularization for the ultraviolet divergences, and they lead to consistent
results. We further investigate the calculations in terms of light-front wave
functions, and find a missing contribution from the instantaneous interaction
in light-front quantization. This clarifies the confusing issues raised
recently in the literature on the spin decomposition of an electron, and will
help to consolidate the spin physics program for nucleons in QCD.Comment: 8 page
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