Light hadron spectrum and decay constants in quenched lattice QCD

Abstract

We present results for light hadrons composed of both degenerate and nondegenerate quarks in quenched lattice QCD. We calculate masses and decay constants using 60 gauge configurations with an $O(a)$-improved fermion action at $\ensuremath{\beta}=6.2$. Using the $\ensuremath{\rho}$ mass to set the scale we find hadron masses within two to three standard deviations of the experimental values (given in parentheses): ${m}_{{K}^{*}}={868}_{\ensuremath{-}8}^{+9}$ MeV (892 MeV), ${m}_{\ensuremath{\varphi}}={970}_{\ensuremath{-}10}^{+20}$ MeV (1020 MeV), ${m}_{N}={820}_{\ensuremath{-}60}^{+90}$ MeV (938 MeV), ${m}_{\ensuremath{\Delta}}={1300}_{\ensuremath{-}100}^{+100}$ MeV (1232 MeV), and ${m}_{\ensuremath{\Omega}}={1650}_{\ensuremath{-}50}^{+70}$ MeV (1672 MeV). Direct comparison with experiment for decay constants is obscured by uncertainty in current renormalizations. However, for ratios of decay constants we obtain $\frac{{f}_{K}}{{f}_{\ensuremath{\pi}}}={1.20}_{\ensuremath{-}2}^{+3}(1.22)$ and $\frac{{f}_{\ensuremath{\varphi}}}{{f}_{\ensuremath{\rho}}}={1.13}_{\ensuremath{-}3}^{+2}(1.22)$.