Scalar mesons in lattice QCD

We explore whether $``{\mathrm{f}}_{0}(600)$ or $\ensuremath{\sigma}''$ exists as a pole in QCD, by a full lattice QCD simulation on the ${8}^{3}\ifmmode\times\else\texttimes\fi{}16$ lattice using the plaquette action and Wilson fermions. It is shown that there exists a $\ensuremath{\sigma}$ pole, whose mass is as low as that of the $\ensuremath{\rho},$ owing to the disconnected diagram of the meson propagator. A discussion is given on the physical content of the $\ensuremath{\sigma}.$