A QCD sum rule calculation for the Y(4140) narrow structure

Abstract

We use the QCD sum rules to evaluate the mass of a possible scalar mesonic state that couples to a molecular $D_s^{\ast }{\bar{D}}_s^{\ast }$ current. We find a mass $m_{D_s^{\ast }{D}_s^{\ast }}=(4.14\pm 0.09)$ GeV, which is in a excellent agreement with the recently observed Y(4140) charmonium state. We consider the contributions of condensates up to dimension eight, we work at leading order in ${\alpha }_s$ and we keep terms which are linear in the strange quark mass $m_s$. We also consider a molecular $D^{\ast }{\bar{D}}^{\ast }$ current and we obtain $m_{D^{\ast }{D}^{\ast }}=(4.13\pm 0.10)$, around 200 MeV above the mass of the Y(3930) charmonium state. We conclude that it is possible to describe the Y(4140) structure as a $D_s^{\ast }{\bar{D}}_s^{\ast }$ molecular state.

Comments: 7 pages, 4 eps figures