Two-photon vibrational transitions in ${\mathrm{O}}_2^{+}$ as probes of variation of the proton-to-electron mass ratio

Ryan Carollo, Alexander Frenett, David Hanneke

Vibrational overtones in deeply bound molecules are sensitive probes for variation of the proton-to-electron mass ratio $\mu$. In nonpolar molecules, these overtones may be driven as…