We present a comprehensive study of the Covariant Confined Quark Model (CCQM), a versatile framework for describing electromagnetic, semileptonic, and nonleptonic decays of heavy mesons and quarkonia. The CCQM is built on a covariant nonlocal quark–hadron interaction Lagrangian that incorporates confinement through vertex functions while preserving gauge invariance. We outline the construction of matrix elements for a wide range of decay processes and emphasize the model’s ability to reproduce decay widths in good agreement with experimental data. The parameters of the model are fixed using known meson masses and decay constants, thereby demonstrating the predictive power of the CCQM in heavy-flavor physics.
Tyulemissov et al. (Tue,) studied this question.