论文标题
$ b \ tosτ^+τ^ - $物理$ z $工厂
$b\to sτ^+τ^-$ Physics at Future $Z$ Factories
论文作者
论文摘要
$ b \ tosτ^+τ^ - $测量值是解决Lepton-Favor-Universality（LFU） - 侵略难题，例如$ r_ {k^{（\ ast）}} $ ANOMALIES。 $ r_ {d^{（*）}} $和$ r_ {j/ψ} $的异常进一步增强了它们的必要性和重要性，因为这两者都涉及第三代lept子。未来的$ z $工厂$ e^-e^+$ colliders处于一个很好的位置，可以进行此类测量，因为它们的生产率相对较高，并且在$ z $ pole的$ b $ ersons的相对较高的生产率和重建效率。为了充分探索这种潜力，我们在四个$ b \中进行一项专门的敏感性研究，以sτ^+τ^ - $基准频道，即$ b^0 \ to k^{\ ast 0}τ^+τ^+τ^ - $，$，$，$ b_s \ toxt τ^+τ^ - $，在未来的$ z $工厂。我们开发了一种完全基于跟踪器的方案，用于重建信号$ b $介子，并引入一种半定量方法来估计其主要背景。模拟表明，可以以精确的$ \ sim \ Mathcal O（10^{ - 7} -10^{ - 6} $的精确度测量的前三个通道的分支比率，以及$ b_s \ toτ^+τ^^ - $的精确$ \ sim \ sim \ sim \ sim \ mathcal o（10^{ - 5} { - 5} $ Z $ at tera $，探索了光度和跟踪器分辨率对预期灵敏度的影响。还提出了这些结果的解释。
$b\to sτ^+τ^-$ measurements are highly motivated for addressing lepton-flavor-universality (LFU)-violating puzzles such as $R_{K^{(\ast)}}$ anomalies. The anomalies of $R_{D^{(*)}}$ and $R_{J/ψ}$ further strengthen their necessity and importance, given that the LFU-violating hints from both involve the third-generation leptons directly. $Z$ factories at the future $e^-e^+$ colliders stand at a great position to conduct such measurements because of their relatively high production rates and reconstruction efficiencies for $B$ mesons at the $Z$ pole. To fully explore this potential, we pursue a dedicated sensitivity study in four $b\to sτ^+τ^-$ benchmark channels, namely $B^0\to K^{\ast 0} τ^+ τ^-$, $B_s\toϕτ^+ τ^-$, $B^+ \to K^+ τ^+ τ^- $ and $B_s \to τ^+ τ^-$, at the future $Z$ factories. We develop a fully tracker-based scheme for reconstructing the signal $B$ mesons and introduce a semi-quantitative method for estimating their major backgrounds. The simulations indicate that branching ratios of the first three channels can be measured with a precision $\sim \mathcal O(10^{-7} - 10^{-6})$ and that of $B_s \to τ^+ τ^-$ with a precision $\sim \mathcal O(10^{-5})$ at Tera-$Z$. The impacts of luminosity and tracker resolution on the expected sensitivities are explored. The interpretations of these results in effective field theory are also presented.
