Proton Isovector Helicity Distribution on the Lattice at Physical Pion Mass
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PhysRevLett.121.242003.pdf
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Author(s) • • • • • • • •
Lin, Huey-Wen
Chen, Jiunn-Wei
Ji, Xiangdong
Jin, Luchang
Li, Ruizi
Liu, Yu-Sheng
Yang, Yi-Bo
Zhang, Jian-Hui
Zhao, Yong
Date Issued
December 2018
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Lin, Huey-Wen, et al. “Proton Isovector Helicity Distribution on the Lattice at Physical Pion Mass.” Physical Review Letters, vol. 121, no. 24, Dec. 2018. © 2018 American Physical Society
Version
Final published version
Abstract
We present a state-of-the-art calculation of the isovector quark-helicity Bjorken-x distribution in the proton using lattice-QCD ensembles at the physical pion mass. We compute quasidistributions at proton momenta P[subscript z]∈{2.2,2.6,3.0} GeV on the lattice and match them systematically to the physical parton distribution using the large-momentum effective theory. We reach an unprecedented precision through high statistics in simulations, large-momentum proton matrix elements, and control of excited-state contamination. The resulting distribution with combined statistical and systematic errors is in agreement with the latest phenomenological analysis of the spin-dependent experimental data, in particular, Δ[¯ over u](x)>Δd[¯ over d](x).
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.121.242003