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arXiv 1912.01720hep-phphysics.acc-ph
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Belle和Belle II实验对四体τ轻子衰变的灵敏度

Sensitivity for four-body tau-lepton decays at Belle and Belle II experiments

I. Domínguez, P. S. Mares Damas, P. L. M. Podesta Lerma, D. Rodríguez Pérez

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摘要：

我们研究了在Belle和Belle II实验室中对四体$τ^\mp \to X^\pm l^\mp l^\mp ν_τ$衰变的预期灵敏度，其中$l=e$或$μ$和$X=π$，$K$，$ρ$和$K^*$介子。这些衰变过程违反了总轻子数（PDMATHAMT），它们可以由Majorana中微子的交换引起。特别是，我们认为在$τ_N$ = 5，100 ps的可访问范围内的寿命和提取的限制$|V_{\ell N}|^2$没有任何额外的假设上的混合矩阵元素的相对大小。对于在Belle收集的1 ab $^{-1}$的综合光度，我们发现BR（$τ^\mp \to X^\pm l^\mp l^\mp ν_τ$）$\sim 10^{-8}$阶的分支分数具有显着的敏感性。对于预期的50 ab $^{-1}$和10 ab $^{-1}$的中间光度的综合光度在美女II，我们发现显着的灵敏度上的分支分数的顺序BR（$τ^\mp \to X^\pm l^\mp l^\mp ν_τ$）$\sim 10^{-9}-10^{-8}$。我们使用这些灵敏度设置限制的排斥区域的参数空间$(m_N, |V_{\ell N}|^2)$与重中微子;这样，对于一个$|V_{\ell N}|^2 \sim \mathcal{O}(10^{-5})$在$τ_N = 100$ ps，我们发现的界限为$0.140 < m_N < 1.776$ GeV的$τ^- \to X^+ e^- e^- ν_τ$和$0.245 < m_N < 1.671 $ GeV的$τ^- \to X^+ μ^- μ^- ν_τ$。

英文摘要：

We study the expected sensitivity at Belle and Belle II for four-body $τ^\mp \to X^\pm l^\mp l^\mp ν_τ$ decays where $l=e$ or $μ$ and $X=π$, $K$, $ρ$ and $K^*$ mesons. These decay processes violate the total lepton number ($|ΔL|=2$ ) and they can be induced by the exchange of Majorana neutrinos. In particular, we consider lifetimes in the accessible ranges of $τ_N$ = 5, 100 ps and extract the limits on $|V_{\ell N}|^2$ without any additional assumption on the relative size of the mixing matrix elements. For an integrated luminosity collected of 1 ab$^{-1}$ at Belle, we found significant sensitivity on branching fractions of the order BR($τ^\mp \to X^\pm l^\mp l^\mp ν_τ$) $\sim 10^{-8}$. For an integrated luminosity expected of 50 ab$^{-1}$ and intermediate luminosity of 10 ab$^{-1}$ at the Belle II, we found significant sensitivity on branching fractions of the order BR($τ^\mp \to X^\pm l^\mp l^\mp ν_τ$) $\sim 10^{-9}-10^{-8}$. We use these sensitivities to set limits for the exclusion regions on the parameter space $(m_N, |V_{\ell N}|^2)$ associated with the heavy neutrino; such that for a $|V_{\ell N}|^2 \sim \mathcal{O}(10^{-5})$ at $τ_N = 100$ ps, we find the bounds as $0.140 < m_N < 1.776$ GeV for $τ^- \to X^+ e^- e^- ν_τ$ and $0.245 < m_N < 1.671 $ GeV for $τ^- \to X^+ μ^- μ^- ν_τ$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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