[en] The asymptotic behavior of two weak decay modes of heavy quark-light quark systems (D or B mesons) in the LLA approximation is calculated with the ratio of the heavy quark and light quark M₂/m₂ as the large parameter. The sum of leading logarithm contributions of all orders of the coupling constant g₂ gives a Sudakov-like double logarithmic factor. This factor indicates that the standard factorization and renormalization group approach as usually formulated does not work for this process. It may also indicate a suppression of these processes, but further analysis is needed