Effect of alpha variation on a prospective experiment to detect variation of m_e/m_p in diatomic molecules

TL;DR

This paper analyzes how variations in the fine structure constant alpha could affect a proposed experiment to detect changes in the electron-to-proton mass ratio mu using diatomic molecules, highlighting potential sensitivity to alpha variation.

Contribution

It demonstrates that the vibrational level splitting in diatomic molecules is sensitive to alpha variation, suggesting the experiment can also probe alpha changes alongside mu.

Findings

Splitting may be equally sensitive to alpha and mu variations.

Alpha variation could influence the experimental results significantly.

The method could serve as a competitive probe for alpha variation.

Abstract

We consider the influence of variation in the fine structure constant alpha on a promising experiment proposed by DeMille et al. to search for variation in the electron-to-proton mass ratio mu using diatomic molecules [DeMille et al., Phys. Rev. Lett. 100, 043202 (2008)]. The proposed experiment involves spectroscopically probing the splitting between two nearly-degenerate vibrational levels supported by different electronic potentials. Here we demonstrate that this splitting may be equally or more sensitive to variation in alpha as to variation in mu. For the anticipated experimental precision, this implies that the alpha variation may not be negligible, as previously assumed, and further suggests that the method could serve as a competitive means to search for alpha variation as well.