An effective model for charmed meson semileptonic decays

We analyze charm meson semileptonic decays using the measured ratios $\Gamma_L/\Gamma_T$ and $\Gamma_{+}/\Gamma_{-}$ from $D\to {\bar K}^{*}$ and the branching ratios for $D \to {\bar K}^{*}$ and $D \to {\bar K}$. First we introduce the light vector mesons in a model which combines the heavy quark effective Lagrangian and the chiral perturbation approach. We propose a method which predicts the behavior of the form factors. Using the available experimental data we determine the values of some model parameters and reproduce the observed branching ratios for $D_{s} \to \Phi$, $D_{s} \to (\eta + \eta^{\prime})$ and $D \to \pi$. We make predictions for the yet unmeasured branching ratios and polarization observables.