标题： 半轻子$B_c$衰变和重夸克自旋对称性 显示英文标题

标题： Semileptonic $B_c$ Decay and Heavy Quark Spin Symmetry

摘要： 介子$B_c$的半轻子衰变在重夸克极限下被研究。 $B_c \rightarrow B_s (B^0),B_s^* (B^{*0})$半轻子衰变的六个可能形式因子由两个不变函数决定。 只有其中一个函数在零动量交换时有贡献，在此情况下，它可以通过介子衰变常数$f_B$和$B_c$波函数的算符乘积展开的最低阶进行计算。 在限制性的运动学区域内，对于$B_c \rightarrow D^0,D^{*0}$和$B_c\rightarrow\eta_c,J/\psi$的半轻子衰变也得到了类似的结果。 半轻子$B_c$衰变提供了一种确定KM混合角$|V_{ub}|$的方法。 显示英文摘要

摘要： Semileptonic decay of the $B_c$ meson is studied in the heavy quark limit. The six possible form factors for $B_c \rightarrow B_s (B^0),B_s^* (B^{*0})$ semileptonic decay are determined by two invariant functions. Only one of these functions contributes at zero recoil, where it is calculable to lowest order in an operator product expansion in terms of the meson decay constant $f_B$ and the $B_c$ wavefunction. A similar result is found for $B_c \rightarrow D^0,D^{*0}$ and for $B_c\rightarrow\eta_c,J/\psi$ semileptonic decay for a restricted kinematic region. Semileptonic $B_c$ decay provides a means for determining the KM mixing angle $|V_{ub}|$.