Ultracold high-spin $\Sigma$-state polar molecules for new physics searches

TL;DR

This paper proposes using ultracold high-spin $ ext{YbCr}$ molecules to enhance searches for electric dipole moments, potentially revealing new physics beyond the Standard Model through improved sensitivity in fundamental symmetry tests.

Contribution

It introduces a new candidate molecule, $ ext{YbCr}$, for high-precision measurements of charge-parity violation, combining relativistic effects and high-spin states for increased sensitivity.

Findings

Predicts sensitivity of $ ext{6} imes 10^{-31} e ext{cm}$ for electron EDM detection.

Shows feasibility of using $ ext{YbCr}$ molecules in spin-precession experiments.

Discusses extensions to quantum control and other fundamental symmetry tests.

Abstract

We propose high-spin $\Sigma$-state polar molecules assembled from ultracold atoms to probe charge-parity violating physics beyond the Standard Model. We identify YbCr as a prime candidate to search for the electric dipole moment of the electron. We show that the combination of relativistic ytterbium and high-spin chromium, amenable to magneto-association, leads to molecules with easy-to-polarize parity doublets and large intramolecular electric fields. Based on \textit{ab initio} results for molecular constants, we predict a sensitivity of $\delta d_{\textrm{e}}= ( 6 \times 10^{-31} / \sqrt{n_{\mathrm{day}}})\,e\,\mathrm{cm}$ via standard spin-precession measurements, we assess the experimental feasibility, and discuss potential extensions to more advanced quantum control as well as searches of the nuclear magnetic quadrupole moment. This work paves the way to next-generation searches for new physics with ultracold molecules in both the leptonic and hadronic sectors.