N(N*) and Delta(Delta*) on the lattice

Abstract

We investigate the mass spectrum of Nucleon and Delta (and its counterparts with strange and charm), and their excited states, in quenched lattice QCD with exact chiral symmetry. For each light baryon, we use 23 masses to determine the coefficients of the mass formula in quenched chiral perturbation theory. By chiral extrapolation to m_\pi=135 MeV, we obtain M_N=958(26) MeV, M_{N*}=1553(42) MeV, M_{Delta}=1216(32) MeV and M_{Delta*}=1611(17) MeV, which are identified with N(939)P_{11},N(1535)S_{11}, Delta(1232)P_{33} and Delta(1620)S_{31} respectively. Further, we directly measure the masses of Omega^{-}, M_{Omega}=1648(60) MeV, and its excited state, M_{Omega*}=1935(48) MeV; as well as the triply charmed baryon Omega_{ccc}^{++}, M_{Omega_{ccc}^{++}}=4931(22) MeV, and its excited state, M_{{\Omega^{++}_{ccc}}^*}=5185(35) MeV.