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

Abstract

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).