标题： D和B介子寿命的计算 显示英文标题

标题： Calculation of the D and B Meson Lifetimes

摘要： 使用重介子衰变宽度在重夸克质量中的展开以及用于估计相应矩阵元的QCD求和规则，我们计算了$D^{\pm,o,s}$的衰变宽度和$B^{\pm,o,s}$的寿命差异。 D介子的结果与数据一致，而预测$[\Gamma (B^o)-\Gamma (B^-)]/\Gamma_B\se 4\%\,,$以及$B^o$和$B_s$介子的寿命差异甚至更小。 详细描述了弱湮灭和泡利干涉对寿命差异的贡献作用。 在自洽计算过程中，找到了许多对于用魅夸克和底夸克介子进行计算至关重要的参数值。 特别是，微扰极点夸克质量为$M_c\se 1.65\,GeV,\,\, M_b\se 5.04\,GeV\,,$，而衰变常数为$f_D(M_c)\se 165\,MeV\,,\,\,f_B(M_b)\se 113\,MeV\,$。 还表明非因子化修正对$B^o-{\bar B}^o$混合影响很大，$B_B\se (1-18\%)\,.$。找到的单位三角形参数值与这些结果以及可用的数据一致（除了 NA31 对$\epsilon ^{\prime}/\epsilon$的结果太大）：$\lambda\se 0.22\,,\,\, A\se 0.825\,,\,\,\rho \se -0.4\,,\,\, \eta \se 0.2\,.$ 显示英文摘要

摘要： Using the expansions of the heavy meson decay widths in the heavy quark mass and QCD sum rules for estimates of corresponding matrix elements,\, we calculate the $D^{\pm,o,s}$ decay widths and the $B^{\pm,o,s}$ lifetime differences. The results for D mesons are in agreement with the data,\, while it is predicted that $[\Gamma (B^o)-\Gamma (B^-)]/\Gamma_B\se 4\%\,,$ and the lifetime difference of the $B^o$ and $B_s$ mesons is even smaller. The role of the weak annihilation and Pauli interference contributions to the lifetime differences are described in detail. In the course of self-consistent calculations the values of many parameters crucial for calculations with charmed and beauty mesons are found. In particular,\, the perturbative pole quark masses are: $M_c\se 1.65\,GeV,\,\, M_b\se 5.04\,GeV\,,$ and the decay constants are: $f_D(M_c)\se 165\,MeV\,,\,\,f_B(M_b)\se 113\,MeV\,$. It is also shown that the nonfactorizable corrections to the $B^o-{\bar B}^o$ mixing are large,\, $B_B\se (1-18\%)\,.$ The values of the unitarity triangle parameters are found which are consistent with these results and the data available (except for the NA31 result for the $\epsilon ^{\prime}/\epsilon$ which is too large): $\lambda\se 0.22\,,\,\, A\se 0.825\,,\,\,\rho \se -0.4\,,\,\, \eta \se 0.2\,.$