SU(3) lattice QCD study for octet and decuplet baryon spectra

TL;DR

This study uses SU(3) lattice QCD with improved techniques to analyze octet and decuplet baryon spectra, providing insights into the nature of $ ext{Λ}(1405)$ and baryon mass splittings.

Contribution

It presents the first quenched lattice QCD calculation of the flavor-singlet negative-parity baryon mass, suggesting $ ext{Λ}(1405)$ is likely not a simple three-quark state.

Findings

The flavor-singlet negative-parity baryon mass is about 1.6 GeV.

$ ext{Λ}(1405)$ is heavier than the observed 1.405 GeV, indicating a possible molecular component.

Mass splittings between baryons depend on the current quark mass.

Abstract

The spectra of octet and decuplet baryons are studied using SU(3) lattice QCD at the quenched level. As an implementation to reduce the statistical fluctuation, we employ the anisotropic lattice with $O(a)$ improved quark action. In relation to $\Lambda(1405)$, we measure also the mass of the SU(3) flavor-singlet negative-parity baryon, which is described as a three quark state in the quenched lattice QCD, and its lowest mass is measured about 1.6 GeV. Since the experimentally observed negative-parity baryon $\Lambda(1405)$ is much lighter than 1.6 GeV, $\Lambda(1405)$ may include a large component of a $N \bar K$ bound state rather than the three quark state. The mass splitting between the octet and the decuplet baryons are also discussed in terms of the current quark mass.