Selecting μ→e conversion targets to distinguish lepton flavour-changing operators
Selecting μ→e conversion targets to distinguish lepton flavour-changing operators
复制标题
选择μ→e转换目标来区分轻子变味算子
DOI：
10.1016/j.physletb.2019.01.042
复制
发表时间：
2019
影响因子：
4.4
通讯作者：
M. Yamanaka
中科院分区：
文献类型：
--
作者：
S. Davidson;Y. Kuno;M. Yamanaka
未来几年，原子核 μ→ e 转换的实验灵敏度将提高四个数量级。然而，各种算子系数在 μ→ e 转换的幅度中连贯地相加，并由核相关函数加权，因此在检测时，识别相关的新物理场景可能很困难。使用核目标作为系数空间中的向量的表示（其分量是加权函数），我们量化了不同核目标可能给出不同约束的期望。我们表明，除了 10 个自旋无关（SI）系数的两种组合外，所有组合都可能受到未来测量的限制，但区分有助于自旋相关（SD）过程的轴、张量和伪标量算子将需要专门的核计算。我们预计 μ→ e 转换可以限制 10 到 14 种系数组合；如果 μ→ e γ 和 μ→ e é e 约束另外 8 个，则在 QED× QCD 不变算子的基础上留下 60 到 64 个“平坦方向”，这些算子描述 μ→ e 低于 m W 的风味变化。
The experimental sensitivity to μ→ e conversion on nuclei is set to improve by four orders of magnitude in coming years. However, various operator coefficients add coherently in the amplitude for μ→ e conversion, weighted by nucleus-dependent functions, and therefore in the event of a detection, identifying the relevant new physics scenarios could be difficult. Using a representation of the nuclear targets as vectors in coefficient space, whose components are the weighting functions, we quantify the expectation that different nuclear targets could give different constraints. We show that all but two combinations of the 10 Spin-Independent (SI) coefficients could be constrained by future measurements, but discriminating among the axial, tensor and pseudoscalar operators that contribute to the Spin-Dependent (SD) process would require dedicated nuclear calculations. We anticipate that μ→ e conversion could constrain 10 to 14 combinations of coefficients; if μ→ e γ and μ→ e e¯ e constrain eight more, that leaves 60 to 64 “flat directions” in the basis of QED× QCD-invariant operators which describe μ→ e flavour change below m W.