Abstract
We present a state-of-the-art calculation of the isovector quark-helicity Bjorken- distribution in the proton using lattice-QCD ensembles at the physical pion mass. We compute quasidistributions at proton momenta 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, .
- Received 29 August 2018
DOI:https://doi.org/10.1103/PhysRevLett.121.242003
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