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

DOI:https://doi.org/10.1103/PHYSREVD.79.114505· OSTI ID:21300872

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

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1. Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046 (United States)
2. RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States)
3. Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)
4. Institute of Particle and Nuclear Studies, KEK, Tsukuba, 305-0801 (Japan)
5. Department of Physics, University of Tokyo, Hongo 7-3-1, Tokyo 113-0033 (Japan)
6. School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)

We report our numerical lattice QCD calculations of the isovector nucleon form factors for the vector and axial-vector currents: the vector, induced tensor, axial-vector, 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%.

• OSTI ID: 21300872
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 11 Vol. 79; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AXIAL-VECTOR CURRENTS
COMPUTERIZED SIMULATION
CONFIGURATION
D QUARKS
DIPOLES
FLAVOR MODEL
FORM FACTORS
GEV RANGE 01-10
ISOVECTORS
LATTICE FIELD THEORY
MAGNETIC MOMENTS
MASS
MOMENTUM TRANSFER
NUCLEONS
PIONS
QUANTUM CHROMODYNAMICS
S QUARKS
U QUARKS
VECTOR CURRENTS