Pseudoscalar Mass and Decay Constant in Lattice QCD with Exact Chiral Symmetry

Abstract

The masses and decay constants of pseudoscalar mesons $D$, $D_s$, and $K$ are determined in quenched lattice QCD with exact chiral symmetry. For 100 gauge configurations generated with single-plaquette action at $\beta =6.1$ on the $20^3\times 40$ lattice, we compute point-to-point quark propagators for 30 quark masses in the range $0.03\le m_{q}a\le 0.80$, and measure the time-correlation functions of pseudoscalar and vector mesons. The inverse lattice spacing $a^{-1}$ is determined with the experimental input of $f_{\pi }$, while the strange quark bare mass ($m_{s}a=0.08$), and the charm quark bare mass ($m_{c}a=0.80$) are fixed such that the masses of the corresponding vector mesons are in good agreement with $\varphi (1020)$ and $J/\psi (3097)$ respectively. Our results of pseudoscalar-meson decay constant are: $f_K=152(6)(10)$ MeV, $f_D=235(8)(14)$ MeV, and $f_{D_s}=266(10)(18)$ MeV [hep-ph/0506266]. The latest experimental result of $f_{D^{+}}$ from CLEO [hep-ex/0508057] is in good agreement with our prediction.

Comments: 6 pages, Talk presented at Lattice 2005, Dublin, 25-30 July 2005