Nucleon form factors with 2+1 flavor dynamical domain-wall fermions

Journal Article · Mon Jun 01 04:00:00 EDT 2009 · Physical Review. D, Particles, Fields, Gravitation and Cosmology

DOI:https://doi.org/10.1103/PhysRevD.79.114505· OSTI ID:1029194

Aoki, Yasumichi ^[1]; Blum, Tom ^[2]; Lin, Huey-Wen ^[3]; Ohta, Shigemi ^[4]; Sasaki, Shoichi ^[5]; Tweedie, Robert ^[6]; Zanotti, James ^[6]

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1. Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center
2. Univ. of Connecticut, Storrs, CT (United States); Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center
3. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
4. High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Sokendai Graduate U. Adv. Studies, Hayama, Kanagawa 240-0193, Japan; Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center
5. Univ. of Tokyo (Japan)
6. Univ. of Edinburgh, Scotland (United Kingdom)

We report our numerical lattice QCD calculations of the isovector nucleon form factors for the vector and axialvector currents: the vector, induced tensor, axialvector, and induced pseudoscalar form factors. The calculation is carried out with the gauge configurations generated with N{sub f} = 2+1 dynamical domain wall fermions and Iwasaki gauge actions at {beta} = 2.13, corresponding to a cutoff a{sup -1} = 1.73 GeV, and a spatial volume of (2.7 fm){sup 3}. The up and down quark masses are varied so the pion mass lies between 0.33 and 0.67 GeV while the strange quark mass is about 12% heavier than the physical one. We calculate the form factors in the range of momentum transfers, 0.2 < q{sup 2} < 0.75 GeV{sup 2}. The vector and induced tensor form factors are well described by the conventional dipole forms and result in significant underestimation of the Dirac and Pauli mean-squared radii and the anomalous magnetic moment compared to the respective experimental values. We show that the axial-vector form factor is significantly affected by the finite spatial volume of the lattice. In particular in the axial charge, g{sub A}/g{sub V}, the finite volume effect scales with a single dimensionless quantity, m{sub {pi}}L, the product of the calculated pion mass and the spatial lattice extent. Our results indicate that for this quantity, m{sub {pi}} L > 6 is required to ensure that finite volume effects are below 1%.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1029194
• Report Number(s): JLAB-THY-09-932; DOE/OR/23177-0680; arXiv:0904.2039
• Journal Information: Physical Review. D, Particles, Fields, Gravitation and Cosmology, Journal Name: Physical Review. D, Particles, Fields, Gravitation and Cosmology Journal Issue: 11 Vol. 79; ISSN PRVDAQ; ISSN 1550-7998
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
DIPOLES
FERMIONS
FORM FACTORS
ISOVECTORS
MAGNETIC MOMENTS
MOMENTUM TRANSFER
NUCLEONS
PIONS
PSEUDOSCALARS
QUANTUM CHROMODYNAMICS
QUARKS
VECTORS