Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany.
Phys Rev Lett. 2012 Jun 1;108(22):222001. doi: 10.1103/PhysRevLett.108.222001. Epub 2012 May 30.
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.
我们使用非微扰改进的 Sheikholeslami-Wohlert 威尔逊作用计算了在约 285 MeV 介子质量和约 0.073 fm 格子间距下，n(f)=2 格点 QCD 中质子自旋的奇异和轻夸克贡献 Δs、Δu 和 Δd。我们对这些矩阵元进行了重整化，其中涉及到来自不同夸克味道的贡献的混合。我们的主要结果是奇异贡献对核子自旋的小负值 Δs(MS)(√(7.4) GeV)=-0.020(10)(4)。第二个误差是由于缺少对物理点的外推而导致的不确定性的估计。
