Exclusive Ds → (η, η′)lν decays in light-cone QCD

Probing the (s) over bars content of the eta and eta' mesons and considering mixing between these states as well as gluonic contributions, the form factors responsible for semileptonic D-s -> (eta, eta')l nu transitions are calculated via light-cone QCD sum rules. Corresponding branching fractions and their ratio for different mixing angles are also obtained. Our results are in a good consistency with experimental data as well as predictions of other nonperturbative approaches.