Excited Baryons from the FLIC Fermion Action

TL;DR

This paper calculates excited baryon masses using quenched lattice QCD with improved actions, revealing mass splittings consistent with previous studies but not reproducing the Lambda*(1405) suppression.

Contribution

It introduces a quenched lattice QCD approach with a fat-link clover fermion action to study excited baryons, confirming mass splittings and exploring hyperon states.

Findings

Mass splitting between nucleon and parity partner observed.

Small mass difference between low-lying J^P={1/2}^- N* states.

No empirical mass suppression of Lambda*(1405) found.

Abstract

Masses of positive and negative parity excited nucleons and hyperons are calculated in quenched lattice QCD using an O(a^2) improved gluon action and a fat-link clover fermion action in which only the irrelevant operators are constructed with fat links. The results are in agreement with earlier N* simulations with improved actions, and exhibit a clear mass splitting between the nucleon and its parity partner, as well as a small mass splitting between the two low-lying J^P={1/2}^- N* states. Study of different Lambda interpolating fields suggests a similar splitting between the lowest two {1/2}^- Lambda* states, although the empirical mass suppression of the Lambda*(1405) is not seen.