P, T-odd Faraday Effect: a New Approach to Improve the Sensitivity of the Search for Time-reflection-noninvariant Interactions in Nature
Year: 2021
Type: conference-paper
Abstract: A search for the time-noninvariant ($\mathcal{T}$-odd) interactions is one of the most fundamental not yet resolved problems in physics. The existence of the electric dipole moment (EDM) for any particle violates both $\mathcal{P}$- and $\mathcal{T}$-invariances ($\mathcal{P}$ is the space parity). The search for the EDMs continues for more than half a century without any success. The present constraint on the $\mathcal{P}$- and $\mathcal{T}$-violating effects is based on the observation of the electron-spin precession in an external electric field using the ThO molecule (ACME collaboration, USA). This experiment sets the upper bound for the electron EDM ($e$EDM) $d_e<1.1\times 10^{-29}$~$e$~cm ($e$ is the electron charge)\footnote{V. Andreev et al. (ACME collaboration), Nature \textbf{562}, 355 (2018)}. An accurate evaluation of the $e$EDM within the standard model is still absent. The maximum estimated value is $d_e \sim 10^{-38}$~$e$~cm\footnote{M. Pospelov, I. Khriplovich, Sov.Nucl.Phys. \textbf{53}, 638 (1991)}. No signs of ``new physics'' inside this gap between the theory and experiment have not yet been found. This encourages to suggest the new, more sensitive methods for observation of the $e$EDM in low-energy physics. We suggest considering the $\mathcal{P}$, $\mathcal{T}$-odd Faraday effect (rotation of the polarization plane for the light propagating through a medium in presence of an external electric field). The experiment is assumed to be performed with the modern intra-cavity/cavity-enhanced absorption spectroscopy techniques in combination with a molecular beam crossing the cavity\footnote{D.V. Chubukov, L.V. Skripnikov, L.N. Labzowsky, JETP Letters \textbf{110}, 382 (2019); D.V. Chubukov, L.V. Skripnikov, A.N. Petrov, V.N. Kutuzov, L.N. Labzowsky, PRA~(2021) [Accepted, to be published; Preprint: arXiv:2102.05157]}. Theoretical simulations of the proposed experiment with the PbF and ThO molecular beams together with accurate molecular structure calculations show that the present constraint on the $e$EDM in principle can be improved by a few orders of magnitude. An advantage of the $\mathcal{P}$, $\mathcal{T}$-odd Faraday experiment is that the $\mathcal{P}$, $\mathcal{T}$-odd effect is cumulated on the light, while in the ACME-like experiment it is cumulated on the molecules. For the shot-noise limited measurement, it is much easier to have a larger number of photons than a larger number of molecules.
Author: Dmitry Chubukov
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G2276964601, G3512009933
OpenAlex ID: W3203671344