Lattice QCD Studies of the Low-Lying ∆ and Λ Resonances in Meson-Baryon Scattering

 Scattering amplitudes for several channels are calculated using lattice QCD on a single ensemble of gauge field configurations with Nf = 2 + 1 dynamical quark flavors and mπ ≈ 200 MeV and mK ≈ 487 MeV. The calculations for the πN scattering amplitudes in the ∆(1232) regime and the coupled channel πΣ-KN¯ scattering am?plitudes in the Λ(1405) regime are detailed. In the coupled channels, two poles are found. The πN s-wave scattering shifts for the total isospins I = 1/2 and I = 3/2, and the p-wave including the ∆(1232) resonance are reported. The coupled channel πΣ-KN s ¯ -wave scattering length is reported. Resonance masses and widths are cal?culated for the ∆(1232), the Λ(1405), and even the elusive Λ(1380). Along with the high-precision scattering amplitudes, methodologies for increasing confidence in our analysis were tested.