Enhanced sensitivity to variation of me/mp in molecular pectra

Abstract

We propose new experiments with high sensitivity to a possible variation of the electron-to-proton mass ratio μ me/mp. We consider a nearly degenerate pair of molecular vibrational levels, each associated with a different electronic potential. With respect to a change in μ, the change in the splitting between such levels can be large both on an absolute scale and relative to the splitting. We demonstrate the existence of such pairs of states in Cs2, where the narrow spectral lines achievable with ultracold molecules make the system promising for future searches for small variations in μ. © 2008 The American Physical Society.