Pion-pion scattering and the timelike pion form factor from $N_f=2+1$ lattice QCD simulations using the stochastic LapH method

Abstract

We report on progress applying the stochastic LapH method to estimate all-to-all propagators required in correlation functions of multi-hadron operators relevant for pion-pion scattering. Largevolume results for I = 2 and I = 1 pion-pion scattering phase shifts with good statistical precision are obtained from an N f = 2 + 1 anisotropic Wilson clover ensemble with m = 240MeV. We also present a preliminary determination of the I = 1 pion-pion scattering phase shift and timelike pion form factor on an isotropic N f = 2 + 1 flavour ensemble generated by the Coordinated Lattice Simulation (CLS) community effort.