Octet-baryon masses in finite space

We report on a recent study of finite-volume effects on the lowest-lying octet baryon masses using the covariant baryon chiral perturbation theory up to next-to-leading order by analysing the latest $n_f = 2 + 1$ lattice QCD results from the NPLQCD Collaboration.Comment: 4 pages, 1 figure; parallel talk delivered by XLR at the 14th national conference on nuclear structure, April 12nd - 16th, 2012, Huzhou, Chin

Scalar strangeness content of the nucleon and baryon sigma terms

The scalar strangeness content of the nucleon, characterized by the so-called strangeness-nucleon sigma term, is of fundamental importance in understanding its sea-quark flavor structure. We report a determination of the octet baryon sigma terms via the Feynman-Hellmann theorem by analyzing the latest high-statistics $n_f=2+1$ lattice QCD simulations with covariant baryon chiral perturbation theory up to next-to-next-to-next-to-leading order. In particular, we predict $\sigma_{\pi N}=55(1)(4)$ MeV and $\sigma_{sN}=27(27)(4)$ MeV, while the first error is statistical and the second systematic due to different lattice scales. The predicted $\sigma_{sN}$ is consistent with the latest LQCD results and the results based on the next-to-next-to-leading order chiral perturbation theory. Several key factors in determining the sigma terms are systematically taken into account and clarified for the first time, including the effects of lattice scale setting, systematic uncertainties originating from chiral expansion truncations, and constraint of strong-interaction isospin breaking effects.Comment: 6 pages, 2 figures; version to appear in Physical Review

Octet baryon masses and sigma terms in covariant baryon chiral perturbation theory

We report an analysis of the octet baryon masses using the covariant baryon chiral perturbation theory up to next-to-next-to-next-to-leading order with and without the virtual decuplet contributions. Particular attention is paid to the finite-volume corrections and the finite lattice spacing effects on the baryon masses. A reasonable description of all the publicly available $n_f=2+1$ lattice QCD data is achieved.Utilyzing the Feynman-Hellmann theorem, we determine the nucleon sigma terms as $\sigma_{\pi N}=55(1)(4)$ MeV and $\sigma_{sN}=27(27)(4)$ MeV.Comment: 4 pages; presented by Xiu-Lei Ren at The Seventh International Symposium on Chiral Symmetry in Hadrons and Nuclei (Chiral 2013), October 27-30, 2013, Beijing, Chin