The structure of the exotic meson X(3872) is still under debate. The similarity of the X(3872) mass and the D-D̄* mass threshold inspired the interpretation that X(3872) is a D-D̄* “molecule” with small binding energy. Another explanation is that this meson is a tetra-quark, consisting of a di-quark and di-antiquark. Relativistic heavy-ion collisions produce an extremely hot and strongly interacting medium, which provides a new environment to study the nature of multi-quark states. Because of the different radii of a D-D̄* “molecule” and a tetra-quark, these two proposed states are expected to interact differently with the medium. Therefore, the yield of X(3872) in heavy-ion collisions can provide insight into its structure. The ratios of production cross-section of fully reconstructed X(3872) over ψ(2S) in PbPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with the CMS detector are presented.
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