{ Q s}{Q (′) s } Molecular States in QCD Sum Rules

We systematically investigate the mass spectra of {Q }{ (') s} molecular states in the framework of QCD sum rules. The interpolating currents representing the molecular states are proposed. Technically, contributions of the operators up to dimension six are included in operator product expansion (OPE). The masses for molecular states with various {Q }{ (') s} configurations are presented. The result 4.36 ± 0.08 GeV for the D* s * s0 molecular state is consistent with the mass 4350 +4.6 −5.1 ± 0.7 MeV of the newly observed X(4350), which could support X(4350) interpreted as a D* s * s0 molecular state.