Lattice study of quark and glue momenta and angular momenta in the nucleon

M. Deka, T. Doi, Y. B. Yang, B. Chakraborty, S. J. Dong, T. Draper, M. Glatzmaier, M. Gong, H. W. Lin, K. F. Liu, D. Mankame, N. Mathur, T. Streuer

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66 Scopus citations


We report a complete calculation of the quark and glue momenta and angular momenta in the proton. These include the quark contributions from both the connected and disconnected insertions. The quark disconnected insertion loops are computed with Z4 noise, and the signal-to-noise ratio is improved with unbiased subtractions. The glue operator is comprised of gauge-field tensors constructed from the overlap operator. The calculation is carried out on a 163×24 quenched lattice at β=6.0 for Wilson fermions with κ=0.154, 0.155, and 0.1555, which correspond to pion masses at 650, 538, and 478 MeV, respectively. The chirally extrapolated u and d quark momentum/angular momentum fraction is found to be 0.64(5)/0.70(5), the strange momentum/angular momentum fraction is 0.024(6)/0.023(7), and that of the glue is 0.33(6)/0.28(8). The previous study of quark spin on the same lattice revealed that it carries a fraction of 0.25(12) of proton spin. The orbital angular momenta of the quarks are then obtained from subtracting the spin from their corresponding angular momentum components. We find that the quark orbital angular momentum constitutes 0.47(13) of the proton spin with almost all of it coming from the disconnected insertions.

Original languageEnglish
Article number014505
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number1
StatePublished - Jan 16 2015

Bibliographical note

Publisher Copyright:
© 2015 American Physical Society.

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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