$(Q\bar{s})^{(*)}(\bar{Q}s)^{(*)}$ molecular states from QCD sum rules: a view on Y(4140)

Understand

Masses for the $(Q\bar{s})^{(*)}(\bar{Q}s)^{(*)}$ ($Q=c$ or $b$) molecular states are systematically computed in the framework of QCD sum rules.

• Technically, contributions of the operators up to dimension six are included in operator product expansion (OPE).
• The numerical result $4.13\pm0.10 {GeV}$ for $D_{s}^{*}\bar{D}_{s}^{*}$ agrees well with the mass $4143.0\pm2.9\pm1.2 {MeV}$ for Y(4140), which supports the $D_{s}^{*}\bar{D}_{s}^{*}$ molecular configuration for Y(4140).