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arXiv 0910.5686hep-lat
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动力学(2+1)味畴壁费米子的核子结构函数

Nucleon structure functions from dynamical (2+1)-flavor domain wall fermions

Shigemi Ohta

摘要:

我们报道了在(a^{-1} \sim 1.7)GeV的晶格截断下,RIKEN-BNL-Columbia(RBC)和UKQCD联合动力学(2+1)味畴壁费米子(BND)系综的核子结构函数的低矩的晶格体积无关性.在< x >< x >两个空间体积((\sim { \rm 2.7 fm})^[3]和((\sim {\rm 1.8 fm})^[3])上研究了完全非微扰重整化的等矢量夸克动量分数(_{u-d})和螺旋度分数(_{Δu - Δd})。它们的自然重整化比(< x >_{u-d}/< x >_{Δu - Δd})不受任何有限尺寸效应的影响。它对轻夸克质量的依赖性不强,与实验结果吻合得很好。各自的绝对值,完全非微扰重整化,不显示任何有限尺寸的影响。它们显示出在最轻的上夸克和下夸克质量下各自的实验值的趋势。这种下降到实验值的趋势似乎是由较轻的夸克驱动的真实物理效应。观测结果与轴向电流形状因子中的巨大有限尺寸效应形成对比。

英文摘要:

We report lattice-volume independence of low moments of nucleon structure functions from the coarse RIKEN-BNL-Columbia (RBC) and UKQCD joint dynamical (2+1)-flavor domain-wall fermions (DWF) ensembles at the lattice cut off of (a^{-1}\sim1.7) GeV. The isovector quark momentum fraction, (< x >_{u-d}), and helicity fraction, (< x >_{Δu - Δd}), both fully non-perturbatively renormalized are studied on two spatial volumes of ((\sim {\rm 2.7 fm})^3) and ((\sim {\rm 1.8 fm})^3). Their naturally renormalized ratio, (< x >_{u-d}/< x >_{Δu - Δd}), is not affected by any finite-size effect. It does not depend strongly on light quark mass and does agree well with the experiment. The respective absolute values, fully non-perturbatively renormalized, do not show any finite-size effect either. They show trending toward the respective experimental values at the lightest up- and down-quark mass. This trending down to the experimental values appears to be a real physical effect driven by lighter quarks. The observations are in contrast to the huge finite-size effect seen in the axial-current form factors.

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