Effect of alpha variation on the vibrational spectrum of Sr_2

TL;DR

This paper investigates how variations in the fine-structure constant alpha affect the vibrational spectrum of Sr₂ molecules, relevant for experiments testing fundamental constant stability.

Contribution

It provides an analysis of the sensitivity of Sr₂ vibrational spectra to alpha variation, comparing it to sensitivity to mu variation in the context of planned experiments.

Findings

Experiment less sensitive to alpha variation than to mu variation by a factor of 3-4.

Results suggest alpha variation may be neglected or require explicit consideration.

Analysis informs interpretation of precision measurements of fundamental constants.

Abstract

We consider the effect of $\alpha$ variation on the vibrational spectrum of Sr$_2$ in the context of a planned experiment to test the stability of $\mu\equiv m_e/m_p$ using optically trapped Sr$_2$ molecules [Zelevinsky et al., Phys. Rev. Lett. {\bf 100}, 043201; Kotochigova et al., Phys. Rev. A {\bf 79}, 012504]. We find the prospective experiment to be 3 to 4 times less sensitive to fractional variation in $\alpha$ as it is to fractional variation in $\mu$. Depending on the precision ultimately achieved by the experiment, this result may give justification for the neglect of $\alpha$ variation or, alternatively, may call for its explicit consideration in the interpretation of experimental results.