title: Strangeness contribution to the proton spin from lattice QCD.
abstract: We compute the strangeness and light-quark contributions Δs, Δu, and Δd to the proton spin in n(f)=2 lattice QCD at a pion mass of about 285 MeV and at a lattice spacing a≈0.073 fm, using the nonperturbatively improved Sheikholeslami-Wohlert Wilson action. We carry out the renormalization of these matrix elements, which involves mixing between contributions from different quark flavors. Our main result is the small negative value Δs(MS)(√(7.4) GeV)=-0.020(10)(4) of the strangeness contribution to the nucleon spin. The second error is an estimate of the uncertainty, due to the missing extrapolation to the physical point.
authors.affiliation: Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany. gunnar.bali@ur.de
authors.forename: Gunnar S
authors.initials: GS
authors.lastname: Bali
authors.forename: Sara
authors.initials: S
authors.lastname: Collins
authors.forename: Meinulf
authors.initials: M
authors.lastname: Göckeler
authors.forename: Roger
authors.initials: R
authors.lastname: Horsley
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Andrea
authors.initials: A
authors.lastname: Nobile
authors.forename: Dirk
authors.initials: D
authors.lastname: Pleiter
authors.forename: P E L
authors.initials: PE
authors.lastname: Rakow
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäfer
authors.forename: Gerrit
authors.initials: G
authors.lastname: Schierholz
authors.forename: James M
authors.initials: JM
authors.lastname: Zanotti