Nucleon form factors on a large volume lattice near the physical point in 2 + 1 flavor QCD

We present results for the isovector nucleon form factors measured on a 964 lattice at almost the physical pion mass with a lattice spacing of 0.085 fm in 2+1 flavor QCD. The configurations are generated with the stout-smeared O(a)-improved Wilson quark action and the Iwasaki gauge action at β=1.82. The pion mass at the simulation point is about 146 MeV. A large spatial volume of (8.1 fm)3 allows us to investigate the form factors in the small momentum transfer region. We determine the isovector electric radius and magnetic moment from nucleon electric (GE) and magnetic (GM) form factors as well as the axial-vector coupling gA. We also report on the results of the axial-vector (FA), induced pseudoscalar (FP) and pseudoscalar (GP) form factors in order to verify the axial Ward-Takahashi identity in terms of the nucleon matrix elements, which may be called the generalized Goldberger-Treiman relation.