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

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 $(250-500)\mathrm{M}\mathrm{e}\mathrm{V}$ above the corresponding $D^{\ast }-{\bar{D}}^{\ast }$, $D_s^{\ast }-{\bar{D}}_s^{\ast }$, $B^{\ast }-{\bar{B}}^{\ast }$ and ${B}_s^\ast -{\bar {B}}_s^\ast$thresholds,theY(4140)isunlikelyascalar${D}_s^\ast {\bar {D}}_s^\ast$molecularstate\mathrm{.}Thescalar$D^\ast {\bar D}^\ast$,$D_s^\ast {\bar D}_s^\ast$,$B^\ast {\bar B}^\ast$and$B_s^\ast {\bar B}_s^\ast$molecularstatesmaybenotexist,whilethescalar${D’}^\ast {\bar {D’}}^\ast$,${D’}_s^\ast {\bar {D’}}_s^\ast$,${B’}^\ast {\bar {B’}}^\ast$and${B’}_s^\ast {\bar {B’}}_s^\ast$ molecular states maybe exist.