First lattice study of low-energy charmonium-hadron interaction

We study the scattering lengths of charmonia (J/psi and eta(c)) with light hadrons (pi, rho, and N) by the quenched lattice QCD simulations on 24(3)x48, 32(3)x48, and 48(3)x48 lattices with the lattice spacing a similar or equal to 0.068 fm. The scattering length is extracted by using the Luscher's phase-shift formula together with the measurement of the energy shift Delta E of two hadrons on the lattice. We find that there exist attractive interactions in all channels, J/psi(eta(c))-pi, J/psi(eta(c))-rho, and J/psi(eta(c))-N: The s-wave J/psi-pi (eta(c)-pi) scattering length is determined as 0.0119 +/- 0.0039 fm (0.0113 +/- 0.0035 fm) and the corresponding elastic cross section at the threshold becomes 0.018(-0.010)(+0.013) mb (0.016(-0.008)(+0.011) mb). Also, the J/psi-N (eta(c)-N) spin-averaged scattering length is 0.71 +/- 0.48 fm (0.70 +/- 0.66 fm), which is at least an order of magnitude larger than the charmonium-pion scattering length. The volume dependence of the energy shifts is also investigated to check the expected 1/L-3 behavior of Delta E at a large spatial size L.