Analysis of the Y(4140) and related molecular states with QCD sum rules

Abstract

In this article, we assume that there exist scalar ${D}^{\ast}{\bar {D}}^{\ast}$, ${D}_{s}^{\ast}{\bar{D}}_{s}^{\ast}$, ${B}^{\ast}{\bar {B}}^{\ast}$ and ${B}_{s}^{\ast}{\bar{B}}_{s}^{\ast}$ molecular states, and study their masses using the QCD sum rules. The numerical results indicate that the masses are about (250–500) MeV above the corresponding D ^*–${\bar{D}}^{\ast}$, D ^* _s –${\bar {D}}_{s}^{\ast}$, B ^*–${\bar{B}}^{\ast}$ and B ^* _s –${\bar {B}}_{s}^{\ast}$ thresholds, the Y(4140) is unlikely a scalar ${D}_{s}^{\ast}{\bar{D}}_{s}^{\ast}$ molecular state. The scalar $D^{\ast}{\bar{D}}^{\ast}$, $D_{s}^{\ast}{\bar{D}}_{s}^{\ast}$, $B^{\ast}{\bar{B}}^{\ast}$ and $B_{s}^{\ast}{\bar{B}}_{s}^{\ast}$ molecular states maybe not exist, while the scalar ${D'}^{\ast}{\bar{D}}^{\prime\ast}$, ${D}_{s}^{\prime\ast}{\bar{D}}_{s}^{\prime\ast}$, ${B}^{\prime\ast}{\bar{B}}^{\prime\ast}$ and ${B}_{s}^{\prime\ast}{\bar{B}}_{s}^{\prime\ast}$ molecular states maybe exist.