Is X(7200) the heavy anti-quark diquark symmetry partner of X(3872)?

Abstract

The D^{(*)}Xi _{cc}^{(*)} system and {bar{Xi }}_{cc}^{(*)}Xi _{cc}^{(*)} system can be related to the D^{(*)}{bar{D}}^{(*)} system via heavy anti-quark di-quark symmetry (HADS). In this work, we employ a contact-range effective field theory to systematically investigate the likely existence of molecules in these systems in terms of the hypothesis that X(3872) is a 1^{++}~D{bar{D}}^{*} bound state in the isospin symmetry limit, with some of the unknown low energy constants estimated using the light-meson saturation approximation. In the meson–meson system, a J^{PC}=2^{++}~{bar{D}}^{*}D^{*} molecule commonly referred to as X(4013) is reproduced, which is the heavy quark spin partner of X(3872). In the meson-baryon system, we predict two triply charmed pentaquark molecules, J^{P}=1/2^{-}~D^{*}Xi _{cc} and J^{P}=5/2^{-}~D^{*}Xi _{cc}^{*}. In the baryon-baryon system, there exist seven di-baryon molecules, J^{PC}=0^{-+}~{bar{Xi }}_{cc}Xi _{cc}, J^{PC}=1^{--}~{bar{Xi }}_{cc}Xi _{cc}, J^{PC}=1^{-+}~{bar{Xi }}_{cc}Xi _{cc}^{*}, J^{PC}=1^{--}~{bar{Xi }}_{cc}Xi _{cc}^{*}, J^{PC}=2^{-+}~{bar{Xi }}_{cc}Xi _{cc}^{*}, J^{PC}=2^{-+}~{bar{Xi }}_{cc}^{*}Xi _{cc}^{*}, and J^{PC}=3^{--}~{bar{Xi }}_{cc}^{*}Xi _{cc}^{*}. Among them, the J^{PC}=0^{-+}~{bar{Xi }}_{cc}Xi _{cc} molecule may contribute to the X(7200) state recently observed by the LHCb Collaboration, which implies that X(7200) can be related to X(3872) via HADS. As a byproduct, with the heavy quark flavor symmetry we also study likely existence of molecular states in the B^{(*)}{bar{B}}^{(*)}, {bar{B}}^{(*)}Xi _{bb}^{(*)}, and {bar{Xi }}_{bb}^{(*)}Xi _{bb}^{(*)} systems.