Light baryon spectrum using improved interpolating operators

Abstract

Energies for excited light baryons are computed in quenched QCD with a pion mass of 490 MeV. Operators used in the simulations include local operators and the simplest nonlocal operators that have nontrivial orbital structures. All operators are designed with the use of Clebsch-Gordan coefficients of the octahedral group so that they transform irreducibly under the group rotations. Matrices of correlation functions are computed for each irreducible representation, and then the variational method is applied to separate mass eigenstates. We obtained 17 states for isospin 1/2 and 11 states for isospin 3/2 in various spin-parity channels including $J^P=5/2^\pm$. The pattern of the lowest-lying energies from each irrep is discussed. We use anisotropic lattices of volume $24^3\times 64$ with temporal lattice spacing $a_t^{-1}=6.05$ GeV with renormalized anisotropy $ξ=3.0$.