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

作者：Yamazaki Takeshi^*; Aoki Yasumichi; Blum Tom; Lin Huey Wen; Ohta Shigemi; Sasaki Shoichi; Tweedie Robert; Zanotti James

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2009, 79(11): 114505.

DOI：10.1103/PhysRevD.79.114505

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(f)=2+1 dynamical domain-wall fermions and Iwasaki gauge actions at beta=2.13, corresponding to a cutoff a(-1)=1.73 GeV, and a spatial volume of (2.7 fm)(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(2)< 0.75 GeV(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(A)/g(V), the finite-volume effect scales with a single dimensionless quantity, m(pi)L, the product of the calculated pion mass and the spatial lattice extent. Our results indicate that for this quantity, m(pi)L > 6 is required to ensure that finite-volume effects are below 1%.

• 出版日期2009-6