Light Quark Dynamics in Charmonium and Bottomonium Systems

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This project aims to investigate the role of chiral symmetry in the properties of the newly discovered XYZ states within the molecular picture. To reach this goal, we propose a systematic approach based on chiral effective field theory which takes into account all relevant scales such as the pion mass, binding momenta and momenta emerging due to the presence of nearby three-body channels involving pion and a charmed/bottom meson pair. We will, in particular, focus on chiral dynamics of the charmonium-type state X(3872) and the bottomonium-type states Z_b(10610) and Z_b(10650). The systematic inclusion of the relevant scales within the effective field theory framework will allow us to make reliable predictions for the molecular spin/isospin partner states of the X(3872) and Z_b resonances. At a later stage of the project implications of the SU(3) flavour symmetry and heavy-quark symmetries will be addressed. These investigations will lead to new insights into the nature of the XYZ states and provide valuable information on their quark mass dependence which is important for ongoing/upcoming lattice-QCD calculations.