Light-Cone Sum Rules for the $D_{(s)}\to {\eta }^{(\prime )}l{\nu }_l$ Form Factor

N. Offen, F. A. Porkert, A. Schafer

We present an improved light-cone sum rule analysis of the decay form factors of $D$ and $D_s$ into $\eta$ and ${\eta }^{\prime }$ and argue that these decays offer a very promissing possibi…