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

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%.