Excited baryons in lattice QCD
2003; American Physical Society; Volume: 67; Issue: 11 Linguagem: Inglês
10.1103/physrevd.67.114506
ISSN1538-4500
AutoresWally Melnitchouk, Sundance Bilson-Thompson, Frédéric Bonnet, J. N. Hedditch, Frank Lee, Derek B. Leinweber, Anthony G. Williams, J. M. Zanotti, J. B. Zhang,
Tópico(s)High-Energy Particle Collisions Research
ResumoWe present the first results for the masses of positive and negative parity excited baryons calculated in lattice QCD using an ${O(a}^{2})$-improved gluon action and a fat-link irrelevant clover (FLIC) fermion action in which only the irrelevant operators are constructed with APE-smeared links. The results are in agreement with earlier calculations of ${N}^{*}$ resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner. A correlation matrix analysis reveals two low-lying ${J}^{P}={\frac{1}{2}}^{\ensuremath{-}}$ states with a small mass splitting. The study of different $\ensuremath{\Lambda}$ interpolating fields suggests a similar splitting between the lowest two $\ensuremath{\Lambda}{\frac{1}{2}}^{\ensuremath{-}}$ octet states. However, the empirical mass suppression of the ${\ensuremath{\Lambda}}^{*}(1405)$ is not evident in these quenched QCD simulations, suggesting a potentially important role for the meson cloud of the ${\ensuremath{\Lambda}}^{*}(1405)$ and/or a need for more exotic interpolating fields.
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