arXiv 2211.016162022-11-03hep-ph

识别中微子振荡背后的最小味对称性

Towards identifying the minimal flavor symmetry behind neutrino oscillations

Zhi-zhong Xing

备注：: 6 pages, 2 figures. Contribution to ICHEP2022

摘要：

目前的中微子振荡数据表明，$3\times 3$ Pontecorvo-Maki-Nakagawa-Sakata矩阵$U$表现出$μ$ - $τ$味交换对称性$|U^{}_{μi}| = |U^{}_{τi}|$（对于$i = 1, 2, 3$）作为一个很好的近似。特别地，T2 K测量意味着最大中微子混合角$θ^{}_{23}$和CP破坏相$δ$应该分别接近于$π/4$和$-π/2$。这些观测结果的背后是一个最小的味对称性- -有效Majorana中微子质量项在$ν^{}_{e \rm L} \to (ν^{}_{e \rm L})^c$，$ν^{}_{μ\rm L} \to (ν^{}_{τ\rm L})^c$和$ν^{}_{τ\rm L} \to (ν^{}_{μ\rm L})^c$变换下保持不变。将这种味对称性推广到正则跷跷板机制，我们发现描述重Majorana中微子弱荷电相互作用强度的$R$矩阵满足$|R^{}_{μi}| = |R^{}_{τi}|$，这是$|U^{}_{μi}| = |U^{}_{τi}|$的结果.这个结果可以用来设置一个新的上限，这是约三个数量级更严格的比以前，与带电轻子的味道违反衰变模式$τ^- \to e^- + γ$的味道混合因子。

英文摘要：

Current neutrino oscillation data indicate that the $3\times 3$ Pontecorvo-Maki-Nakagawa-Sakata matrix $U$ exhibits a $μ$-$τ$ flavor interchange symmetry $|U^{}_{μi}| = |U^{}_{τi}|$ (for $i = 1, 2, 3$) as a good approximation. In particular, the T2K measurement implies that the maximal neutrino mixing angle $θ^{}_{23}$ and the CP-violating phase $δ$ should be close to $π/4$ and $-π/2$, respectively. Behind these observations lies a minimal flavor symmetry -- - the effective Majorana neutrino mass term keeps invariant under the transformations $ν^{}_{e \rm L} \to (ν^{}_{e \rm L})^c$, $ν^{}_{μ\rm L} \to (ν^{}_{τ\rm L})^c$ and $ν^{}_{τ\rm L} \to (ν^{}_{μ\rm L})^c$. Extending this flavor symmetry to the canonical seesaw mechanism, we find that the $R$-matrix describing the strength of weak charged-current interactions of heavy Majorana neutrinos satisfies $|R^{}_{μi}| = |R^{}_{τi}|$ as a consequence of $|U^{}_{μi}| = |U^{}_{τi}|$. This result can be used to set a new upper bound, which is about three orders of magnitude more stringent than before, on the flavor mixing factor associated with the charged-lepton-flavor-violating decay mode $τ^- \to e^- + γ$.

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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英文摘要：

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