title: Lattice study of the exotic s = +1 baryon.
abstract: We propose S = +1 baryon interpolating operators, which are based on an exotic description of the antidecuplet baryon, like the diquark-diquark-antiquark structure. By using one of the new operators, the mass spectrum of the spin-1/2 pentaquark states is calculated in quenched lattice QCD at beta = 6/g(2) = 6.2 on a 32(3) x 48 lattice. It is found that the J(P) assignment of the lowest Theta(uudds) state is most likely (1/2)(-). We also calculate the mass of the charm analog of the Theta and find that the Theta(c)(uuddc) state lies much higher than the DN threshold, in contrast to several model predictions.
authors.affiliation: Department of Physics, University of Tokyo, Tokyo 113-0033, Japan. ssasaki@phys.s.u-tokyo.ac.jp
authors.forename: Shoichi
authors.initials: S
authors.lastname: Sasaki