Charmonium resonances on the lattice

¹ Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
² Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
³ Jozef Stefan Institute, 1000 Ljubljana, Slovenia
⁴ Helmholtz-Institut Mainz, 55099 Mainz, Germany
⁵ Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany

^* Speaker, e-mail: stefano.piemonte@physik.uni-regensburg.de
^** Speaker, e-mail: simon.weishaeupl@physik.uni-regensburg.de

Published online: 26 March 2018

Abstract

The nature of resonances and excited states near decay thresholds is encoded in scattering amplitudes, which can be extracted from single-particle and multiparticle correlators in finite volumes. Lattice calculations have only recently reached the precision required for a reliable study of such correlators. The distillation method represents a significant improvement insofar as it simplifies quark contractions and allows one to easily extend the operator basis used to construct interpolators. We present preliminary results on charmonium bound states and resonances on the N_f = 2+1 CLS ensembles. The long term goal 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. As a first result, we present the masses of the ground and excited states in the 0⁺⁺ and 1⁻⁻ channels