Scalar and Tensor Charmonium Resonances in Coupled-Channel Scattering from Lattice QCD

We determine J PC = 0 ++ and 2 ++ hadron-hadron scattering amplitudes in the charmonium energy region up to 4100 MeV using lattice QCD, a first -principles approach to QCD. Working at m pi approximate to 391 MeV, more than 200 finite -volume energy levels are computed and these are used in extensions of the L & uuml;scher formalism to determine infinite -volume coupled -channel scattering amplitudes. We find that this energy region contains a single chi c 0 and a single chi c 2 resonance. Both are found as pole singularities on the closest unphysical Riemann sheet, just below 4000 MeV with widths around 70 MeV. The largest couplings are to kinematically closed D * <overline> D * channels in S -wave, and couplings to several decay channels consisting of pairs of open -charm mesons are found to be large and significant in both cases. Above the ground state chi c 0 , no other scalar bound states or near- D D <overline> threshold resonances are found, in contrast to several theoretical and experimental studies.