Optical clocks based on molecular vibrations as probes of variation of the proton-to-electron mass ratio

TL;DR

This paper explores the potential of molecular vibrational transitions at optical frequencies as highly accurate clocks to detect possible variations in the proton-to-electron mass ratio, which could indicate new physics beyond the Standard Model.

Contribution

It introduces the concept of using optical molecular clocks based on vibrational transitions to probe fundamental constant variations, highlighting experimental developments and their potential sensitivity.

Findings

Molecular vibrational transitions can serve as precise probes for fundamental constant variations.

Current experiments aim to detect drifts or oscillations in the proton-to-electron mass ratio.

Projected uncertainties make these experiments promising for next-generation tests.

Abstract

Some new physics models of quantum gravity or dark matter predict drifts or oscillations of the fundamental constants. A relatively simple model relates molecular vibrations to the proton-to-electron mass ratio $\mu$. Many vibrational transitions are at optical frequencies with prospects for use as highly accurate optical clocks. We give a brief summary of new physics models that lead to changes in $\mu$ and the current limits on drifts and oscillation amplitudes. After an overview of laboratory procedures, we give examples of molecules with experiments currently in development or underway. These experiments' projected systematic and statistical uncertainties make them leading candidates in next-generation searches for time-variation of $\mu$.