Nucleon form factors with 2+1 flavor dynamical domain-wall fermions
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(Published version)
Date
2009
Authors
Yamazaki, T.
Aoki, Y.
Blum, T.
Lin, H.
Ohta, S.
Sasaki, S.
Tweedie, R.
Zanotti, J.
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Physical Review D: Particles, Fields, Gravitation and Cosmology, 2009; 79(11):114505:1-114505:20
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Takeshi Yamazaki, Yasumichi Aoki, Tom Blum, Huey-Wen Lin, Shigemi Ohta, Shoichi Sasaki, Robert Tweedie and James Zanotti (RBC and UKQCD Collaborations)
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Abstract
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 Nf=2+1 dynamical domain-wall fermions and Iwasaki gauge actions at β=2.13, corresponding to a cutoff a-1=1.73GeV, and a spatial volume of (2.7fm)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<q2<0.75GeV2. 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, gA/gV, the finite-volume effect scales with a single dimensionless quantity, mπL, the product of the calculated pion mass and the spatial lattice extent. Our results indicate that for this quantity, mπL>6 is required to ensure that finite-volume effects are below 1%. © 2009 The American Physical Society.
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© 2009 The American Physical Society