Low-lying $\Lambda$ Baryons with spin 1/2 in Two-flavor Lattice QCD

Abstract

Low-lying $\Lambda$ baryons with spin 1/2 are analyzed in full (unquenched) lattice QCD. We construct $2\times 2$ cross correlators from flavor SU(3) "octet" and "singlet" baryon operators, and diagonalize them so as to extract information of two low-lying states for each parity. The two-flavor CP-PACS gauge configurations are used, which are generated in the renormalization-group improved gauge action and the $\mathcal{O}(a)$-improved quark action. Three different $\beta$'s, $\beta =1.80$, 1.95 and 2.10, are employed, whose corresponding lattice spacings are $a=0.2150$, 0.1555 and 0.1076 fm. For each cutoff, we use four hopping parameters, (${\kappa }_{\mathrm{val}},{\kappa }_{\mathrm{sea}}$), which correspond to the pion masses ranging about from 500 MeV to 1.1 GeV. Results indicate that there are two negative-parity $\Lambda$ states nearly degenerate at around 1.6 GeV, while no state as low as $\Lambda (1405)$ is observed. By decomposing the flavor components of each state, we find that the lowest (1st-excited) negative-parity state is dominated by flavor-singlet (flavor-octet) component. We also discuss meson-baryon components of each state, which has drawn considerable attention in the context of multi-quark pictures of $\Lambda (1405)$.

11 pages, 11 figures, 3 tables; version to appear in Phys. Rev. D

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• Excited hadrons on the lattice: Baryons
• Excited State Nucleon Spectrum with Two Flavors of Dynamical Fermions
• Signatures of S-wave bound-state formation in finite volume
• Pseudoscalar-meson--octet-baryon coupling constants in two-flavor lattice QCD
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Cited by in corpus (16)

• Light Hadron Masses from Lattice QCD
• QCD with Two Light Dynamical Chirally Improved Quarks: Baryons
• Meson and baryon spectrum for QCD with two light dynamical quarks
• Isolating the Λ(1405) in Lattice QCD
• QCD and the Strange Baryon Spectrum
• Low-lying Lambda Baryons from the Lattice
• Two-pole nature of the $\Lambda (1405)$ from lattice QCD
• Lattice QCD study of $\pi \Sigma -\bar{K}N$ scattering and the $\Lambda (1405)$ resonance
• Strategy to find the two $\Lambda (1405)$ states from lattice QCD simulations
• Flavor structure of $\Lambda$ baryons from lattice QCD: From strange to charm quarks
• Hadron-hadron interaction from SU(2) lattice QCD
• The negative-parity spin-1/2 $\Lambda$ baryon spectrum from lattice QCD and effective theory
• Pole trajectories of the $\Lambda (1405)$ helps establish its dynamical nature
• On ambiguities of sign determination of the S-matrix from energy levels in a finite box
• $\Lambda (1405)$ from lattice QCD
• Chirally motivated $\pi \Sigma$-$\bar{K}N$ model in a finite volume