Sensitivity of microwave and FIR spectra to variation of fundamental constants

TL;DR

This paper evaluates how microwave and FIR spectral lines in molecules like CH and NH2D are sensitive to changes in fundamental constants alpha and mu, aiding the search for their possible variation.

Contribution

It provides calculated sensitivity coefficients for specific molecular transitions, highlighting their dependence on quantum numbers and potential for fundamental constant variation detection.

Findings

Large sensitivity coefficients identified for specific molecular transitions.

Sensitivity strongly depends on quantum numbers of the transitions.

Results support using these transitions in fundamental constant variation searches.

Abstract

We estimate sensitivity coefficients to variation of the fine-structure constant alpha and electron-to-proton mass ratio mu for microwave Lambda-type transitions in CH molecule and for inversion-rotational transitions in partly deuterated ammonia NH2D. Sensitivity coefficients for these systems are large and strongly depend on the quantum numbers of the transition. This can be used for the search for possible variation of alpha and mu.