We derive the $k_T$ resummation for doubly heavy-flavored $B_c$ meson decaysby including the charm quark mass effect into the known formula for aheavy-light system. The resultant Sudakov factor is employed in theperutrbative QCD (PQCD) study of the "golden channel" $B_c^+ \to J/\psi \pi^+$.With a reasonable model for the $B_c$ meson distribution amplitude, whichmaintains approximate on-shell conditions of both the partonic bottom and charmquarks, it is observed that the imaginary piece of the $B_c \to J/\psi$transition form factor appears to be power suppressed, and the $B_c^+ \toJ/\psi \pi^+$ branching ratio is not lower than $10^{-3}$. The above improvedPQCD formalism is applicable to $B_c$ meson decays to other charmonia andcharmed mesons.
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机译：通过将夸克质量夸克效应包括到重轻系统的已知公式中，我们得出了加倍重味的$ B_c $介子衰变的$ k_T $恢复。结果得出的Sudakov因子用于“黄金通道” $ B_c ^ + \ to J / \ psi \ pi ^ + $的微扰QCD（PQCD）研究中。具有合理的$ B_c $介子分布振幅模型，该模型保持近似在partonic底部和charmquarks的壳条件下，可以观察到虚假的$ B_c \ to J / \ psi $过渡形状因数似乎被抑制了功率，并且$ B_c ^ + \ toJ / \ psi \ pi ^ + $分支比率不低于$ 10 ^ {-3} $。上述改进的PQCD形式主义适用于$ B_c $介子衰变到其他魅力和介子介子。
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