Pion form factors from two-flavor lattice QCD with exact chiral symmetry
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8571 (Japan)
- Physics Department, Center for Theoretical Sciences, and Center for Quantum Science and Engineering, National Taiwan University, Taipei, 10617, Taiwan (China)
- Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)
- KEK Theory Center, High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan)
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan (China)
- Computing Research Center, High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan)
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
We calculate pion vector and scalar form factors in two-flavor lattice QCD and study the chiral behavior of the vector and scalar radii <r{sup 2}>{sub V,S}. Numerical simulations are carried out on a 16{sup 3}x32 lattice at a lattice spacing of 0.12 fm with quark masses down to {approx}m{sub s}/6, where m{sub s} 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 m{sub s}/6 to m{sub s}/2. Chiral extrapolation based on two-loop ChPT yields <r{sup 2}>{sub V}=0.409(23)(37) fm{sup 2} and <r{sup 2}>{sub S}=0.617(79)(66) fm{sup 2}, which are consistent with phenomenological analysis. We also present our estimates of relevant low-energy constants.
- OSTI ID:
- 21322372
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 3; Other Information: DOI: 10.1103/PhysRevD.80.034508; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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