SU ( 3 ) lattice QCD study for octet and decuplet baryon spectra ∗

The spectra of octet and decuplet baryons are studied using SU(3) lattice QCD at the quenched level. As an implementation to reduce the statistical fluctuation, we employ the anisotropic lattice with O(a) improved quark action. In relation to Λ(1405), we measure also the mass of the SU(3) flavor-singlet negative-parity baryon, which is described as a three quark state in the quenched lattice QCD, and its lowest mass is measured about 1.6 GeV. Since the experimentally observed negative-parity baryon Λ(1405) is much lighter than 1.6 GeV, Λ(1405) may include a large component of a NK̄ bound state rather than the three quark state. The mass splitting between the octet and the decuplet baryons are also discussed in terms of the current quark mass.