Lattice QCD Study of the Pentaquark Baryons

Abstract

We study the spin $\frac{1}{2}$ hadronic state in quenched lattice QCD to search for a possible $S=+1$ pentaquark resonance. Simulations are carried out on $8^3\times 24$, $10^3\times 24$, $12^3\times 24$ and $16^3\times 24$ lattices at $\beta$=5.7 at the quenched level with the standard plaquette gauge action and Wilson quark action. We adopt two independent operators with I=0 and $J^P=\frac{1}{2}$ to construct a $2\times 2$ correlation matrix. After the diagonalization of the correlation matrix, we successfully obtain the energies of the ground-state and the 1st excited-state in this channel. The volume dependence of the energies suggests the existence of a possible resonance state slightly above the NK threshold in I=0 and $J^P={\frac{1}{2}}^{-}$ channel.

Comments: Talk given at the International Workshop on PENTAQUARK04, SPring-8, Japan, 20-23 July 2004; 7 pages, 3 figures