@article{oai:tsukuba.repo.nii.ac.jp:00018236,
 author = {青木, 愼也 and Aoki, S. and Chiu, T. W. and Fukaya, H. and Hashimoto, S. and Hsieh, T. H. and Kaneko, T. and Matsufuru, H. and Noaki, J. and Onogi, T. and Shintani, E. and Yamada, N.},
 issue = {3},
 journal = {Physical review D},
 month = {Aug},
 note = {We calculate pion vector and scalar form factors in two-flavor lattice QCD and study the chiral behavior of the vector and scalar radii <r2>V,S. Numerical simulations are carried out on a 163×32 lattice at a lattice spacing of 0.12 fm with quark masses down to ~ms/6, where ms is the physical strange quark mass. Chiral symmetry, which is essential for a direct comparison with chiral perturbation theory (ChPT), is exactly preserved in our calculation at finite lattice spacing by employing the overlap quark action. We utilize the so-called all-to-all quark propagator in order to calculate the scalar form factor including the contributions of disconnected diagrams and to improve statistical accuracy of the form factors. A detailed comparison with ChPT reveals that the next-to-next-to-leading-order contributions to the radii are essential to describe their chiral behavior in the region of quark mass from ms/6 to ms/2. Chiral extrapolation based on two-loop ChPT yields <r2>V=0.409(23)(37) fm2 and <r2>S=0.617(79)(66) fm2, which are consistent with phenomenological analysis. We also present our estimates of relevant low-energy constants.},
 title = {Pion form factors from two-flavor lattice QCD with exact chiral symmetry},
 volume = {80},
 year = {2009}
}