The Exotic Baryon Theta^+(1540) on the Lattice

TL;DR

This study uses lattice QCD techniques to investigate the existence of the pentaquark Theta^+(1540), finding no evidence for positive parity states and inconclusive results for negative parity, while identifying scattering states.

Contribution

The paper applies chirally improved fermions and smeared sources in lattice QCD to analyze the Theta^+ pentaquark, providing new insights into its parity and scattering states.

Findings

No evidence for positive parity Theta^+

Detected nucleon-kaon scattering states

Results for negative parity are inconclusive

Abstract

We report on a study of the pentaquark Theta^+(1540), using a variety of different interpolating fields. We use Chirally Improved fermions in combination with Jacobi smeared quark sources to improve the signal and get reliable results even for small quark masses. The results of our quenched calculations, which have been done on a 12^3x24 lattice with a lattice spacing of a=0.148 fm, do not provide any evidence for the existence of a Theta^+ with positive parity. We do observe, however, a signal compatible with nucleon-kaon scattering state. For the negative parity the results are inconclusive, due to the potential mixture with nucleon-kaon and N*-kaon scattering states.