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Moments of Nucleon's Parton Distribution for the Sea and Valence Quarks from Lattice QCD

Journal Article · · Preprint to be distributed
We extend the study of lowest moments, $$ and $$, of the parton distribution function of the nucleon to include those of the sea quarks; this entails a disconnected insertion calculation in lattice QCD. This is carried out on a $$16^3 \times 24$$ quenched lattice with Wilson fermion. The quark loops are calculated with $$Z_2$$ noise vectors and unbiased subtractions, and multiple nucleon sources are employed to reduce the statistical errors. We obtain 5$$\sigma$$ signals for $$ for the $u,d,$ and $$s$$ quarks, but $$ is consistent with zero within errors. We provide results for both the connected and disconnected insertions. The perturbatively renormalized $$ for the strange quark at $$\mu = 2$$ GeV is $$_{s+\bar{s}} = 0.027 \pm 0.006$$ which is consistent with the experimental result. The ratio of $$ for $$s$$ vs. $u/d$ in the disconnected insertion with quark loops is calculated to be $$0.88 \pm 0.07$$. This is about twice as large as the phenomenologically fitted $\displays
Research Organization:
Thomas Jefferson Lab National Accelerator Facility
Sponsoring Organization:
USDOE
OSTI ID:
956302
Report Number(s):
JLAB-THY-08-932; arXiv:0811.1779; DOE-OR-23177-0620
Journal Information:
Preprint to be distributed, Journal Name: Preprint to be distributed
Country of Publication:
United States
Language:
English