Search for the decay $D^+_{s}\to\omega e^+\nu$
  We present the first search for the decay $D^+_{s}\to \omega e^{+}\nu$ to test the four-quark content of the $D^+_{s}$ and the $\omega$-$\phi$ mixing model for this decay. We use 586 $\mathrm{pb}^{-1}$ of $e^{+}e^{-}$ collision data collected at a center-of-mass energy of 4170 MeV. We find no evidence of a signal, and set an upper limit on the branching fraction of $\mathcal{B}(D^+_{s}\to\omega e^+\nu)<$0.20% at the 90% confidence level. 
CLEO Collaboration: L. Martin, A. Powell, G. Wilkinson, J. Y. Ge, D.   H. Miller, I. P. J. Shipsey, B. Xin, G. S. Adams, B. ...
hep-ex