Moments of Nucleon's Parton Distribution for the Sea and Valence Quarks from Lattice QCD
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 National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-060R23177
- OSTI ID:
- 956302
- Report Number(s):
- JLAB-THY-08-932; arXiv:0811.1779; DOE-OR-23177-0620; TRN: US1004986
- Journal Information:
- Preprint to be distributed, Journal Name: Preprint to be distributed
- Country of Publication:
- United States
- Language:
- English
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