Title: Shedding Light on the "Dark Side" of $B^0_d$--$\bar B^0_d$ Mixing through $B_d\toπ^+π^-$, $K\toπν\barν$ and $B_{d,s}\toμ^+μ^-$ Show Chinese title

Title: 揭示$B^0_d$--$\bar B^0_d$混合的“暗面”通过$B_d\toπ^+π^-$, $K\toπν\barν$和$B_{d,s}\toμ^+μ^-$

Abstract: In a wide class of NP models, which can be motivated through generic arguments and within SUSY, we obtain large contributions to $B^0_d$--$\bar B^0_d$ mixing, but not to $\Delta B=1$ processes. If we assume such a scenario, the solutions $\phi_d\sim 47^\circ\lor 133^\circ$ for the $B^0_d$--$\bar B^0_d$ mixing phase implied by $A_{CP}^{mix}(B_d\to J/\psi K_S)$ cannot be converted directly into a constraint in the $\rho$--$\eta$ plane. However, we may complement $\phi_d$ with $|V_{ub}/V_{cb}|$ and the recently measured CP asymmetries in $B_d\to\pi^+ \pi^-$ to determine the unitarity triangle, with its angles $\alpha$, $\beta$ and $\gamma$. To this end, we have also to control penguin effects, which we do by means of the $B_d\to\pi^\mp K^\pm$ branching ratio. Interestingly, the present data show a perfectly consistent picture not only for the ``standard'' solution of $\phi_d\sim 47^\circ$, but also for $\phi_d\sim 133^\circ$. In the latter case, the preferred region for the apex of the unitarity triangle is in the second quadrant, allowing us to accommodate conveniently $\gamma>90^\circ$, which is also favoured by other non-leptonic B decays such as $B\to\pi K$. Moreover, also the prediction for BR$(K^+\to\pi^+\nu\bar\nu})$ can be brought to better agreement with experiment. Further strategies to explore this scenario with the help of $B_{d,s}\to\mu^+\mu^-$ decays are discussed as well. Show Chinese abstract

Abstract: 在一大类NP模型中，这些模型可以通过一般性论证以及在超对称框架内得到解释，我们得到了对$B^0_d$--$\bar B^0_d$混合的大贡献，但不对$\Delta B=1$过程产生大的贡献。 如果我们假设这样的场景，由$A_{CP}^{mix}(B_d\to J/\psi K_S)$推导出的$\phi_d\sim 47^\circ\lor 133^\circ$对于$B^0_d$--$\bar B^0_d$混合相的解无法直接转化为$\rho$--$\eta$平面中的约束。 然而，我们可以将$\phi_d$与$|V_{ub}/V_{cb}|$以及最近测量的$B_d\to\pi^+ \pi^-$中的 CP 异常性结合起来，以确定单位三角形，其角度为$\alpha$、$\beta$和$\gamma$。 为此，我们也必须控制 penguin 效应，我们通过$B_d\to\pi^\mp K^\pm$的分支比来实现这一点。 有趣的是，目前的数据不仅对于“标准”解$\phi_d\sim 47^\circ$，而且对于$\phi_d\sim 133^\circ$都显示出完全一致的图景。在后一种情况下，单位三角形顶点的首选区域位于第二象限，使我们能够方便地容纳$\gamma>90^\circ$，这也被其他非轻子B衰变如$B\to\pi K$所支持。此外，BR$(K^+\to\pi^+\nu\bar\nu})$的预测也可以与实验更好地一致。还讨论了利用$B_{d,s}\to\mu^+\mu^-$衰变探索此情景的进一步策略。