Chiral Properties of Pseudoscalar Mesons

One of the main goals of lattice QCD is to understand from first principles low-energy phenomenology as a consequence of chiral symmetry. Recent advances in the formulation of chiral fermions on the lattice hold great promise for studying chiral symmetry of QCD at finite lattice spacing.

	Figure 4   Renormalized fPa2/fa vs. m2a2, which confirms that the chiral log singularity is indeed present in fP. The solid line is a fit over the lowest 14 points.

Dong et al. used the overlap fermion on a quenched 20⁴ lattice to numerically study the chiral properties of pseudoscalar mesons. They elucidated the role of the zero modes in the meson propagators, particularly that of the pseudoscalar meson. The non-perturbative renormalization constant Z_A was determined from the axial Ward identity and was found to be almost independent of the quark mass for the range of quark masses studied; this implies that the O(a²) error is small. The pion decay constant f was calculated, from which the lattice spacing of 0.148 fm was determined. The authors looked for the quenched chiral log in the pseudoscalar decay constants and the pseudoscalar masses and found clear evidence for its presence (Figure 4). The chiral log parameter was determined to be in the range 0.15–0.4, which is consistent with that predicted from quenched chiral perturbation theory.

The overlap fermion was shown to be a reliable tool for studying the chiral symmetry properties of hadrons at low energies, including the quenched chiral logs. Future work will study the continuum limit with different lattice spacings.

INVESTIGATORS
K. F. Liu, S. J. Dong, T. Draper, and I. Horváth, University of Kentucky; F. X. Lee, George Washington University and Jefferson Laboratory; J. B. Zhang, University of Adelaide, Australia.

PUBLICATION
S. J. Dong, T. Draper, I. Horváth, F. X. Lee, K. F. Liu, and J. B. Zhang, “Chiral properties of pseudoscalar mesons on a quenched 20⁴ lattice with overlap fermions,” Phys. Rev. D 65, 054507 (2002).

URL
http://www.pa.uky.edu/~liu/