Excited and exotic charmonium, $D_s$ and $D$ meson spectra for two light   quark masses from lattice QCD
  We present highly-excited charmonium, $D_s$ and $D$ meson spectra from dynamical lattice QCD calculations with light quarks corresponding to $M_{\pi} \sim 240$ MeV and compare these to previous results with $M_{\pi} \sim 400$ MeV. Utilising the distillation framework, large bases of carefully constructed interpolating operators and a variational procedure, we extract and reliably identify the continuum spin of an extensive set of excited mesons. These include states with exotic quantum numbers which, along with a number with non-exotic quantum numbers, we identify as having excited gluonic degrees of freedom and interpret as hybrid mesons. Comparing the spectra at the two different $M_\pi$, we find only a mild light-quark mass dependence and no change in the overall pattern of states. 
Gavin K. C. Cheung, Cian O'Hara, Graham Moir, Michael Peardon,   Sin\'ead M. Ryan, Christopher E. Thomas, David Tims
hep-lat hep-ph