Precision spectroscopy of atoms and molecules allows one to search for and to put stringent limits on the variation of fundamental constants. These experiments are typically interpreted in terms of variations of the fine structure constant α and the electron‐to‐proton mass ratio $\mu =m_e/m_p$. Atomic spectroscopy is usually less sensitive to other fundamental constants, unless the hyperfine structure of atomic levels is studied. However, the number of possible dimensionless constants increases when allowed for fast variations of the constants, where “fast” is determined by the time scale of the response of the studied species or experimental apparatus used. In this case, the relevant dimensionless quantity is, for example, the ratio $m_e/⟨m_e⟩$ and $⟨m_e⟩$ is the time average. In this sense, one may say that the experimental signal depends on the variation of dimensionful constants ( $m_e$ in this example).

中文翻译：

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基本常数的快速表观振荡

原子和分子的精密光谱学使人们能够寻找和限制基本常数的变化。这些实验通常用精细结构常数α和电子质子质量比的变化来解释$\mu ={米}_{Ë}/{米}_p$。除非研究原子级的超精细结构，否则原子光谱通常对其他基本常数不太敏感。但是，当允许常数快速变化时，可能的无量纲常数的数量会增加，其中“快速”由所研究物种或所用实验装置的响应时间尺度决定。在这种情况下，相关的无量纲数量例如是比率${米}_{Ë}/⟨{米}_{Ë}⟩$ 和 $⟨{米}_{Ë}⟩$是平均时间。在这种意义上，可以说实验信号取决于尺寸常数的变化（${米}_{Ë}$ 在此示例中）。