论文标题
$ cp $不对称$τ\至k_sπν_τ$衰减的角度分布
$CP$ asymmetry in the angular distribution of $τ\to K_Sπν_τ$ decays
论文作者
论文摘要
在这项工作中，我们研究了$ CP $不对称的$τ\至K_Sπν_τ$衰减的角度分布，考虑到已知的$ cp $违规行为$ k^0- \ bar {k}^0 $混合。可以首次指出，一旦调用了中性kaon系统中的$ CP $违规，即使在标准模型中，也会在所考虑的衰减的角度观察到非零$ CP $不对称。通过采用倒数基础，当$ k_ {s（l）} $涉及最终状态时，这是最方便的，$ cp $ accpulation Asservable可观察得出的两倍是时间相关$ cp $ abymmetry in $ k \ to $ k \ toπ^+π^+π^ - $和$ pp pp^pp^$ the $ cp^pp^^use的平均值。 k^0（\ bar {k}^0）π^\ pm \barν_τ（ν_τ）$衰减。与在$kπ$不变质量的四个不同仓中测量的美女结果相比，我们的预测位于这些测量值的边缘内，除了最低质量箱的$ 1.7〜σ $偏差。虽然低于$ \ MATHCAL {O}（10^{ - 3}）$的当前Belle检测敏感性，但预计我们的预测将在Belle II实验中可检测到，其中$ \ sqrt {70} $ timper timerm timpers更敏感的结果将获得$ 50〜 \ text text〜\ text ab ab} ab {ab} $ 1} $ 1} $ 1} $ 1}。
In this work, we study the $CP$ asymmetry in the angular distribution of $τ\to K_Sπν_τ$ decays, taking into account the known $CP$ violation in $K^0-\bar{K}^0$ mixing. It is pointed out for the first time that, once the well-measured $CP$ violation in the neutral kaon system is invoked, a non-zero $CP$ asymmetry would appear in the angular observable of the decays considered, even within the Standard Model. By employing the reciprocal basis, which is most convenient when a $K_{S(L)}$ is involved in the final state, the $CP$-violating angular observable is derived to be two times the product of the time-dependent $CP$ asymmetry in $K\to π^+π^-$ and the mean value of the angular distribution in $τ^\pm\to K^0(\bar{K}^0)π^\pm\barν_τ(ν_τ)$ decays. Compared with the Belle results measured in four different bins of the $Kπ$ invariant mass, our predictions lie within the margins of these measurements, except for a $1.7~σ$ deviation for the lowest mass bin. While being below the current Belle detection sensitivity that is of $\mathcal{O}(10^{-3})$, our predictions are expected to be detectable at the Belle II experiment, where $\sqrt{70}$ times more sensitive results will be obtained with a $50~\text{ab}^{-1}$ data sample.
