Negative-Parity Baryons in Quenched Anisotropic Lattice QCD

TL;DR

This study uses quenched anisotropic lattice QCD to analyze negative-parity baryon spectra, finding that the Lambda(1405) likely has a multi-quark structure rather than a simple three-quark state.

Contribution

First lattice QCD calculation of negative-parity baryons including flavor-singlet states, providing insights into the structure of Lambda(1405).

Findings

Flavor octet and decuplet negative-parity baryon masses match experimental data.

Flavor-singlet negative-parity baryon is much heavier than Lambda(1405).

Lambda(1405) may be a multi-quark state, not a simple three-quark baryon.

Abstract

We study negative-parity baryon spectra in quenched anisotropic lattice QCD. The negative-parity baryons are measured as the parity partner of the ground-state baryons. In addition to the flavor octet and decuplet baryons, we pay much attention to the flavor-singlet negative-parity baryon as a three-quark state and compare it with the Lambda(1405) baryon. Numerical results of the flavor octet and decuplet negative-parity baryon masses are close to experimental values of lowest-lying negative-parity baryons, while the flavor-singlet baryon is much heavier than Lambda(1405). This indicates that the Lambda(1405) would be a multi-quark state such as the N-Kbar molecule rather than the flavor-singlet 3 quark state.