Enhanced sensitivity to variation of the fine structure constant and m_p/m_e in diatomic molecules

TL;DR

This paper discusses how certain diatomic molecules can be used to detect tiny variations in fundamental constants by exploiting near-degenerate energy levels, with potential for highly sensitive measurements.

Contribution

It introduces a method to enhance sensitivity to fundamental constant variations using near-degenerate molecular energy levels, applicable to various molecules.

Findings

Enhanced sensitivity due to near-degenerate levels in molecules

Suitable for microwave frequency measurements with high precision

Potential to detect small variations in fundamental constants

Abstract

Sensitivity to temporal variation of the fundamental constants may be strongly enhanced in transitions between narrow close levels of different nature. This enhancement may be realized in a large number of molecules due to cancelation between the ground state fine structure omega_f and vibrational interval omega_v (omega=omega_f - n omega_v is close to zero, delta omega/omega= K (2 delta alpha/alpha +0.5 delta mu/mu), K >>1, mu=m_p/m_e). The intervals between the levels are conveniently located in microwave frequency range and the level widths are very small. Required accuracy of the shift measurements is about 0.01-1 Hz. As examples, we consider molecules Cl_2+, CuS, IrC, SiBr and HfF+.