Progress on Meson-Baryon Scattering

Abstract

Progress in computing various meson-baryon scattering amplitudes is presented on a single ensemble from the Coordinated Lattice Simulations (CLS) consortium with $m_\pi=200$ MeV and $N_f=2+1$ dynamical fermions. The finite-volume L\"uscher approach is employed to determine the lowest few partial waves from ground- and excited-state energies computed from correlation matrices rotated in a single pivot using a generalized eigenvector solution. This analysis requires evaluating matrices of correlation functions between single- and two-hadron interpolating operators which are projected onto definite spatial momenta and finite-volume irreducible representations. The stochastic LapH method is used to estimate all needed quark propagators. Preliminary results are presented for $I=\frac{1}{2}, \frac{3}{2}$ $N\pi$ amplitudes including the $\Delta(1232)$ resonance and the $I=0$ $S$-wave amplitude with unit strangeness relevant for the $\Lambda(1405)$.