The nature of resonances and excited states near decay thresholds is encoded in phase shifts, which can be extracted from single-particle and multiparticle correlators in finite volumes. Lattice calculations have only recently reached the required precision for a reliable study of such correlators. The distillation method has been a significative improvement insofar as it simplifies quark contractions and allows one to easily extend the operator basis used to construct meson interpolators. We present preliminary results on charmonium bound states and resonances on the $N_f=2+1$ CLS ensembles. The main aim of our investigation is to understand the properties of the X resonances that do not fit into conventional models of quark-antiquark mesons. We tune various parameters of the distillation method and the charm quark mass. In particular we present the masses of the ground and excited states in the $0^{++}$ and $1^{--}$ channels and discuss the existance and the mass of the excited state of the $\chi_{c0}$.

Hadron Spectroscopy and Interactions