A search for varying fundamental constants using Hz-level frequency measurements of cold CH molecules

Abstract

Many modern theories predict that the fundamental constants depend on time, position, or the local density of matter. We develop a spectroscopic method for pulsed beams of cold molecules, and use it to measure the frequencies of microwave transitions in CH with accuracy down to 3 Hz. By comparing these frequencies with those measured from sources of CH in the Milky Way, we test the hypothesis that fundamental constants may differ between the high and low density environments of the Earth and the interstellar medium. For the fine structure constant we find Δα/α= (0.3 +/- 1.1)*10^{-7}, the strongest limit to date on such a variation of α. For the electron-to-proton mass ratio we find Δμ/μ= (-0.7 +/- 2.2) * 10^{-7}. We suggest how dedicated astrophysical measurements can improve these constraints further and can also constrain temporal variation of the constants.

8 pages, 3 figures

References in corpus (6)

• Environmental Dependence of Masses and Coupling Constants
• New Limits on Coupling of Fundamental Constants to Gravity Using ${}^{87}$Sr Optical Lattice Clocks
• Stability of the proton-to-electron mass ratio
• Bounds on the fine structure constant variability from FeII absorption lines in QSO spectra
• $\Lambda$-doublet spectra of diatomic radicals and their dependence on fundamental constants
• Precision measurements with polar molecules: the role of the black body radiation

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