发表机构
Indian Association for the Cultivation of Science; Indian Institute of Technology Kanpur; Joint Institute for Nuclear Research; Indian Institute of Science（印度科学文化研究所; 坎普尔印度理工学院; 俄罗斯杜布纳联合核研究所; 印度科学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究在SMEFT中分析τ sector CLFV向μ→e sector的传播，识别三种μ→e可观测量诱导机制，发现需同时考虑六维RG跑动与八维混合贡献，且μ→e数据对τ味违反的探测灵敏度远高于直接τ衰变约束。
AI 中文摘要
我们在标准模型有效场论（SMEFT）框架内研究τ sector中产生的带电轻子味违反（CLFV）如何传播到μ→e sector。假设Λ≫v尺度下的新物理仅产生介导τ→e和τ→μ跃迁的六维算符，我们识别并比较诱导μ→e可观测量的三种机制，所有三种机制均源自两个τ→ℓ算符的双插入，标度为C₆^τe C₆^τμ / Λ⁴。（T1）重整化群混合使带电轻子质量矩阵失准，旋转到质量基产生六维μ→e算符；（T2）有限的非对数余项，我们发现其可忽略；（T3）整体发散对八维算符进行重整化，在电弱对称性破缺后产生贡献。由于T1和T3无Λ的相对幂次，在任何尺度下都不能忽略，只有比较二者才能揭示哪种机制（以及哪种μ→e可观测量）最能探测给定的算符对。我们对Warsaw基算符进行调研，将代表性（τ→e,τ→μ）对分为T1主导、T3主导及T1-T3相当的区域，并通过潜在混合链解释层级关系。将当前μ→eγ、μ→eee和μ→e转换的限制转化为对τ→ℓ威尔逊系数乘积的约束，我们发现这些限制比直接τ衰变约束高出10到数百倍。对某些算符对，排除T1或T3会使这些限制相差数个量级，对其他算符对则相差2到3倍。因此，将μ→e数据解释为τ味违反的探针需要同时考虑六维RG跑动和八维混合贡献。
英文摘要
We study how charged-lepton flavour violation (CLFV) generated in the $τ$ sector propagates into the $μ\to e$ sector within the Standard Model Effective Field Theory (SMEFT). Assuming that new physics at a scale $Λ\gg v$ produces only dimension-6 operators that mediate $τ\to e$ and $τ\toμ$ transitions, we identify and compare the three mechanisms that induce $μ\to e$ observables. All three originate from double insertions of the two $τ\to\ell$ operators and scale as $C_6^{τe}C_6^{τμ}/Λ^4$. (T1) Renormalization-group mixing misaligns the charged-lepton mass matrix, and the rotation to the mass basis generates dimension-6 $μ\to e$ operators. (T2) A finite, non-logarithmic remainder, which we find to be negligible. (T3) The overall divergence renormalizes dimension-8 operators, contributing after electroweak symmetry breaking. Since T1 and T3 carry no relative power of $Λ$, neither can be neglected at any scale, and only their comparison reveals which mechanism, and hence which $μ\to e$ observable, most strongly probes a given operator pair. Surveying the Warsaw-basis operators, we classify representative $(τ\to e,τ\toμ)$ pairs into T1-dominated, T3-dominated, and T1--T3-comparable regimes, and explain the hierarchy through the underlying mixing chains. Translating current $μ\to eγ$, $μ\to eee$ and $μ\to e$ conversion limits into bounds on products of $τ\to\ell$ Wilson coefficients, we find that they exceed the direct $τ$-decay constraints by factors of ten to several hundred. Excluding either T1 or T3 would miss these limits by orders of magnitude for some pairs, and shift them by factors of two to three in others. Interpreting $μ\to e$ data as a probe of $τ$ flavour violation therefore requires both the dimension-6 RG running and the dimension-8 mixing contributions.
Comments43 pages, 12 figures
