QCD sum rules study of X(4350)

Understand

The QCD sum rule approach is used to analyze the nature of the rencently observed new resonance $X(4350)$, which is assumed to be a diquark-antidiquark state $[cs][\bar{c}\bar{s}]$ with $J^{PC}=1^{-+}$.

• The interpolating current representing this state is proposed.
• In the calculation, contributions of operators up to dimension six are included in the operator product expansion (OPE), as well as terms which are linear in the strange quark mass $m_s$.
• We find $m_{1^{-+}}=(4.82\pm 0.19)\,\mbox{GeV}$, which is not compatible with the $X(4350)$ structure as a $1^{-+}$ tetraquark state.