From analysis of data produced by the BABAR experiment, the first upper bounds (90% C.L.) were obtained on the branching ratios $\mathrm{Br}(\tau \to e\gamma \gamma )<2.5\times {10}^{-4}$ and $\mathrm{Br}(\tau \to \mu \gamma \gamma )<5.8\times {10}^{-4}$. In addition, improved upper bounds (95% C.L.) were found on branching ratios $\mathrm{Br}(\tau \to eX)<1.4\times {10}^{-3}$ and $\mathrm{Br}(\tau \to \mu X)<2.0\times {10}^{-3}$, where $X$ is an undetected weakly interacting boson with mass $m_X<1.6\mathrm{GeV}/c^2$.

中文翻译：

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轻子-风味违反衰变的支化率上限τ→ℓγγ和τ→ℓX

根据对BABAR实验产生的数据的分析，获得了支化率的第一个上限（90% CL）$溴(\tau \to \mathrm{电子}\gamma \gamma )<2.5\times {10}^{-4}$ 和 $溴(\tau \to \mu \gamma \gamma )<5.8\times {10}^{-4}$. 此外，在支化率上发现了改进的上限 (95% CL)$溴(\tau \to \mathrm{电子}X)<1.4\times {10}^{-3}$ 和 $溴(\tau \to \mu X)<2.0\times {10}^{-3}$， 在哪里 $X$ 是一种未被发现的与质量弱相互作用的玻色子 ${米}_X<1.6\mathrm{电子伏特}/C^2$.