Weak Decays of D and Ds Mesons in a Relativistic Quark Model**The project supported in part by National Natural Science Foundation of China and the State Education Commission of China

Abstract

The transitions of D and Ds, mesons to light vector states are studied in a relativistic constituent quark model based on the Bethe–Salpeter formalism. The form factors are calculated, and the branching fractions for both semileptonic and nonleptonic decays are given. The results show that the form factors for these transitions deviate substantially from the request of heavy quark symmetry. All the branching ratios for D and Ds semileptonic decays are found to be consistent with data, whereas the calculations of nonleptonic D and Ds decays under the factorization assumption do not agree with experiments. This confirms the conjecture that the factorization scheme is much less applicable in D and Ds decays than in B and Bs decays.