We calculate the intrinsic quark spin contribution to the total proton spin using overlap valence quarks on three ensembles of 2 + 1-flavor RBC/UKQCD domain-wall configurations with different lattice spacings. The lowest pion mass of the ensembles is around 171 MeV which is close to the physical point. With overlap fermions and topological charge derived from the overlap operator, we verify the anomalous Ward identity between nucleon states with momentum transfer. Both the connected and disconnected insertions of the axial-vector arXiv:1806.08366v2 [hep-ph]

We present a detailed lattice calculation of the unpolarized isovector quark PDF from the largemomentum effective theory approach. In this calculation, the quasi-PDF is defined by a spatial correlator that is free from mixing with operators of the same dimension, and is nonperturbatively renormalized in a regularization-independent momentum subtraction scheme. The renormalized quasi-PDF is then matched to the MS PDF at one-loop order in perturbative QCD. The lattice simulation is done using Gaussian-momentum-smeared source at Mπ = 310 MeV with the nucleon momentum Pz ∈ {1.7, 2.15, 2.6} GeV. Five source-sink separations have been used in our analysis to control the systematics associated with excited-state contamination. The systematic errors due to renormalization and perturbative matching are carefully studied. The final result is in reasonable agreement with the PDF from the latest phenomenological analyses.

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