Pion form factors from two-flavor lattice QCD with exact chiral symmetry
Journal
Physical Review D - Particles, Fields, Gravitation and Cosmology
Journal Volume
80
Journal Issue
3
Date Issued
2009
Author(s)
Abstract
We calculate pion vector and scalar form factors in two-flavor lattice QCD and study the chiral behavior of the vector and scalar radii r2V,S. Numerical simulations are carried out on a 163×32 lattice at a lattice spacing of 0.12fm 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 r2V=0.409(23)(37)fm2 and r2S=0.617(79)(66)fm2, which are consistent with phenomenological analysis. We also present our estimates of relevant low-energy constants. © 2009 The American Physical Society.
SDGs
Type
journal article