Chiral Lagrangian Parameters for Scalar and Pseudoscalar Mesons

TL;DR

This study uses quenched lattice QCD to determine chiral Lagrangian parameters for scalar and pseudoscalar mesons, providing insights into meson properties and chiral loop effects at different lattice spacings.

Contribution

It presents the first high-statistics determination of quenched chiral Lagrangian parameters from lattice QCD for scalar and pseudoscalar mesons, including the effects of quenched chiral loops.

Findings

Estimated chiral Lagrangian parameters $L_5$ and $L_8$.

Determined the mass and decay constant of the $a_0$ meson.

Analyzed quenched chiral loop effects on scalar meson correlators.

Abstract

The results of a high-statistics study of scalar and pseudoscalar meson propagators in quenched lattice QCD are presented. For two values of lattice spacing, $\beta=5.7$ ($a \approx .18$ fm) and 5.9 ($a \approx .12$ fm), we probe the light quark mass region using clover improved Wilson fermions with the MQA pole-shifting ansatz to treat the exceptional configuration problem. The quenched chiral loop parameters $m_0$ and $\alpha_{\Phi}$ are determined from a study of the pseudoscalar hairpin correlator. From a global fit to the meson correlators, estimates are obtained for the relevant chiral Lagrangian parameters, including the Leutwyler parameters $L_5$ and $L_8$. Using the parameters obtained from the singlet and nonsinglet pseudoscalar correlators, the quenched chiral loop effect in the nonsinglet scalar meson correlator is studied. By removing this QCL effect from the lattice correlator, we obtain the mass and decay constant of the ground state scalar, isovector meson $a_0$.