Search for the pentaquark resonance signature in lattice QCD

Claims concerning the possible discovery of the Θ⁺ pentaquark, with minimal quark content uudds̅ , have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various spin-1/2 pentaquark interpolating fields in the literature and create a new candidate ideal for lattice QCD simulations. Using these interpolating fields we attempt to isolate a signal for a five-quark resonance. Calculations are performed using improved actions on a large 20³×40 lattice in the quenched approximation. The standard lattice resonance signal of binding at quark masses near the physical regime, observed for established baryon resonances, is not observed for spin-1/2 pentaquark states. Thus we find no evidence supporting the existence of a spin-1/2 pentaquark resonance in quenched QCD.