Moments of nucleon's parton distribution for the sea and valence quarks from lattice QCD
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg (Germany)
- Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 40005 (India)
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)
We extend the study of lowest moments, <x> and <x{sup 2}>, 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{sup 3}x24 quenched lattice with Wilson fermion. The quark loops are calculated with Z{sub 2} noise vectors and unbiased subtractions, and multiple nucleon sources are employed to reduce the statistical errors. We obtain 5{sigma} signals for <x> for the u, d, and s quarks, but <x{sup 2}> is consistent with zero within errors. We provide results for both the connected and disconnected insertions. The perturbatively renormalized <x> for the strange quark at {mu}=2 GeV is <x>{sub s+s}=0.027{+-}0.006 which is consistent with the experimental result. The ratio of <x> for s vs u/d in the disconnected insertion with quark loops is calculated to be 0.88{+-}0.07. This is about twice as large as the phenomenologically fitted (<x>{sub s+s}/<x>{sub u}+<x>{sub d}) from experiments where u and d include both the connected and disconnected insertion parts. We discuss the source and implication of this difference.
- OSTI ID:
- 21308436
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 79, Issue 9; Other Information: DOI: 10.1103/PhysRevD.79.094502; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
Similar Records
Valence QCD: Connecting QCD to the quark model
Isovector and isoscalar tensor charges of the nucleon from lattice QCD