Pentaquark hadrons from lattice QCD

TL;DR

This study uses quenched lattice QCD to investigate the heta^+ pentaquark, finding evidence supporting a negative parity state with a mass matching experimental observations, while addressing various uncertainties.

Contribution

First lattice QCD analysis to determine the parity and mass of the heta^+ pentaquark considering multiple uncertainties.

Findings

The I^P=0^- state mass matches experimental heta^+ mass.

The I^P=0^+ state mass is significantly higher.

Results suggest heta^+ has negative parity.

Abstract

We study spin 1/2 isoscalar and isovector candidates in both parity channels for the recently discovered \Theta^+(1540) pentaquark particle in quenched lattice QCD. Our analysis takes into account all possible uncertainties, such as statistical, finite size and quenching errors when performing the chiral and continuum extrapolations and we have indications that our signal is separated from scattering states. The lowest mass that we find in the I^P=0^- channel is in complete agreement with the experimental value of the \Theta^+ mass. On the other hand, the lowest mass state in the opposite parity I^P=0^+ channel is much higher. Our findings suggests that the parity of the \Theta^+ is negative.