Observation ofe+e−→Ds±Ds*∓ats=4.14GeV

We present evidence for the exclusive reaction $e^{+}{e}^{-}\to {D_s}^{\pm }{D_s}^{*\mp }$, observed with the Mark III detector at the SLAC storage ring SPEAR. The ${D_s}^{\pm }$ is reconstructed in the $\phi {\pi }^{\pm }$ decay mode, while the ${D_s}^{*\mp }$ is detected as a narrow peak in the recoil-mass distribution. The mass of the ${D_s}^{*}$ is found to be 2109.3±2.1±3.1 MeV/${\mathit{c}}^2$, yielding a ${D_s}^{*}-D_s$ mass difference of 137.9±2.1±4.3 MeV/${\mathit{c}}^2$. The width of the ${D_s}^{*}$ is <22 MeV/${\mathit{c}}^2$ at the 90%-confidence level. The observed signal corresponds to $\sigma (e^{+}{e}^{-}\to {D_s}^{+}{D_s}^{*-}+{D_s}^{-}{D_s}^{*+})B({D_s}^{+}\to \phi {\pi }^{+})=30\mathrm{}\pm 6\pm 11$ pb at $\sqrt{s}=4.14\mathrm{}$ GeV.