Effective model for charmed meson semileptonic decays

Abstract

We analyze charm meson semileptonic decays using the measured ratios Γ L /Γ T and Γ + /Γ − from D →K * and the branching ratios for D →K * and D →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 → Φ, D s → (η + η ′ ) and D → π. We make predictions for the yet unmeasured branching ratios and polarization observables.

Penguin operators in nonresonantB−→MM¯π−Fajfer1, Oakes2, Pham3 1999Phys. Rev. DSelf Cite391450View full textAdd to dashboardCite

“…For the calculation of the matrix elements < M|qγ µ b|B > and < MM|qγ µ γ 5 b|B > we generalize the results obtained in the analysis of D meson semileptonic decays described in detail in [15] and [21]. The matrix element < M|qγ µ (1 − γ 5 )b|B > is given by [21,22] …”

“…Our modification is quite straightforward: we retain the usual HQET Feynman rules for the vertices near and outside the zero-recoil region, but we include the complete propagators instead of using the usual HQET propagator. This quite reasonable modification of the hybrid HQET and CHPT model enabled us to use it successfully over the entire kinematic region of the D meson weak decays [15,21,22].…”

Cabibbo allowedD→Kπγdecays

“…It has to be included, since it is of the same order in the 1/m Q and chiral expansion as the term proportional to α 1 [20]. The relevant matrix element is parametrized usually in D → V lν l semileptonic decay as [16,19,20,38]…”

“…For the evaluation of the (D, D * ) → (P, V ) transitions, we use the information obtained for these matrix elements from semileptonic decays (see, e.g. [20]). The general theoretical framework for our calculation is that of the heavy quark chiral Lagrangian [21,22].…”

“…where α = f H √ m H [21], α 1 was first introduced by Casalbuoni et al [23], while α 2 was introduced in [20]. It has to be included, since it is of the same order in the 1/m Q and chiral expansion as the term proportional to α 1 [20].…”