Parity ($\mathcal{P}$)–violating pseudoscalar or pseudovector cosmic fields are invoked in different models for cold dark matter or in the standard model extension that allows for Lorentz invariance violation. A direct detection of the timelike component of such fields requires a direct measurement of $\mathcal{P}$-odd potentials or their evolution over time. Herein, advantageous properties of chiral molecules, in which $\mathcal{P}$-odd potentials lead to resonance frequency differences between enantiomers, for direct detection of such $\mathcal{P}$-odd cosmic field interactions are demonstrated. Scaling behavior of electronic structure enhancements of such interactions with respect to nuclear charge number and the fine-structure constant is derived analytically. This allows a simple estimate of the effect sizes for arbitrary molecules. The analytical derivation is supported by quasirelativistic numerical calculations in the molecules ${\mathrm{H}}_2{X}_2$ and ${\mathrm{H}}_{2}X\mathrm{O}$ with $X =$ O, S, Se, Te, or Po. Parity-violating effects due to cosmic fields on the C–F stretching mode in CHBrClF are compared to electroweak parity violation and influences of nonseparable anharmonic vibrational corrections are discussed. On this basis, Gaul et al. [Phys. Rev. Lett. 125, 123004 (2020)] estimated from a 20-year-old experiment with CHBrClF that bounds on Lorentz invariance violation as characterized by the parameter $|b_0^{\mathrm{e}}|$ can be pushed down to the order of ${10}^{-17}\mathrm{GeV}$ in modern experiments with suitably selected molecular system, which will be an improvement of the current best limits by at least two orders of magnitude. This serves to highlight the particular opportunities that precision spectroscopy of chiral molecules provides in the search for new physics beyond the standard model.

• Received 11 May 2020
• Accepted 12 August 2020

DOI:https://doi.org/10.1103/PhysRevA.102.032816