Coupled-channel Dπ, Dη and Ds(K)over-bar scattering from lattice QCD

We present the first lattice QCD study of coupled-channel D pi, D eta and Ds (K) over bar scattering in isospin-1/2 in three partial waves. Using distillation, we compute matrices of correlation functions with bases of operators capable of resolving both meson and meson-meson contributions to the spectrum. These correlation matrices are analysed using a variational approach to extract the finite-volume energy eigenstates. Utilising Luscher's method and its extensions, we constrain scattering amplitudes in S, P and D-wave as a function of energy. By analytically continuing the scattering amplitudes to complex energies, we investigate the S-matrix singularities. Working at m(pi) approximate to 391 MeV, we find a pole corresponding to a J(P) = 0(+) near-threshold bound state with a large coupling to D pi. We also find a deeply bound J(P) = 1(-) state, and evidence for a J(P) = 2(+) narrow resonance coupled predominantly to D pi. Elastic D pi scattering in the isospin-3/2 channel is studied and we find a weakly repulsive interaction in S-wave.