2018/07/31 by Huey-Wen Lin, Jiunn-Wei Chen, Xiangdong Ji +7 · 108 citations
Physics and Astronomy · #Excited state #Helicity #High-Energy Particle Collisions Research #Isovector #Lattice QCD #Lattice field theory #Nuclear physics #Nucleon #Particle physics #Particle physics theoretical and experimental studies #Parton #Physics #Pion #Proton #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quark #hep-ex #hep-lat #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevlett.121.242003
published in Physical Review Letters 121(24), 242003 (American Physical Society) · 6 pages, 4 figures
openalex publication_date 2018/12/14 · arxiv created 2019/01/28 · arxiv updated 2019/01/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
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 Pz∈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, Δu[over ¯](x)>Δd[over ¯](x).