Lattice QCD Study of the Pentaquark Baryons

TL;DR

This study uses lattice QCD simulations to investigate the existence of a pentaquark resonance with specific quantum numbers, analyzing volume dependence to identify potential resonance states.

Contribution

It provides the first lattice QCD evidence suggesting a possible pentaquark resonance slightly above the NK threshold in the I=0, J^P=1/2^- channel.

Findings

Possible resonance state identified above NK threshold

Volume dependence supports resonance interpretation

Ground and excited state energies successfully extracted

Abstract

We study the spin $\frac12$ 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 $J^P=\frac12$ 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 $J^P=\frac12^-$ channel.