Abstract

The theories beyond the Standard Model and General Relativity allow space-time variability of fundamental constants [1]. Such variability imply a dependence of the frequencies of atomic and molecular transitions that may be constrained in laboratory by repetitive frequency ratios measurements of two clocks. The strategy for improving the constraint is to increase the accuracy of the clock transitions, to exploit transitions highly sensitive to a variation of fundamental constants, and to perform measurements during a long period of time. The molecular spectra are primarily sensitive to proton-electron mass ratio (µ) variations. The absolute frequency measurements of a rovibrational transition of SF₆ constrained µ-variation at 5.6×10⁻¹⁴ yr^-1 [2]. This contribution discusses progress towards laboratory measurements of electronic transitions of the molecular iodine in the optical domain to constrain a time-variation of fundamental constants.

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