Excited Baryon Spectroscopy from Lattice QCD: Finite Size Effect and Hyperfine Mass Splitting

A study of the finite-size effect is carried out for spectra of both ground-state and excited-state baryons in quenched lattice QCD using Wilson fermions. Our simulations are performed at beta=6.2 with three different spatial sizes, La~1.6, 2.2 and 3.2 fm. It is found that the physical lattice size larger than 3 fm is required for delta states in all spin-parity (J^{P}=1/2^{+/-}, 3/2^{+/-}) channels and also negative-parity nucleon state (J^{P}=1/2^{-}) even in the rather heavy quark mass region. We also find a peculiar behavior of the finite-size effect on the hyperfine mass splittings between the nucleon and the delta in both parity channels.