Light-Cone Sum Rules for the $D_{(s)}\rightarrow η^{(\prime)} l ν_l$ Form Factor

Abstract

We present an improved light-cone sum rule analysis of the decay form factors of $D$ and $D_s$ into $η$ and $η^{\prime}$ and argue that these decays offer a very promissing possibility to determine the leading Fock-state gluonic contribution of the $η'$ at future experimental facilities as FAIR or Super-KEKB. We also give the corresponding branching ratios for B decays.

10 pages, 5 figures, Minor wording changes and some references added, results unchanged