Lasercooled RaF as a promising candidate to measure molecular parity violation

TL;DR

This paper predicts that radium fluoride (RaF) has a large parity-violation parameter and favorable electronic structure, making it a promising candidate for laser cooling and high-precision measurements of fundamental symmetry violations.

Contribution

The study provides the first calculation of the parity-violation parameter $W_ ext{a}$ for RaF using advanced relativistic quantum chemistry methods, highlighting its suitability for experimental tests.

Findings

RaF has one of the largest predicted $W_ ext{a}$ values.

RaF's electronic structure allows for efficient laser cooling.

RaF is suitable for high-precision parity violation experiments.

Abstract

The parameter $W_\mathrm{a}$, which characterizes nuclear spin-dependent parity violation effects within the effective molecular spin-rotational Hamiltonian, was computed for the electronic ground state of radium fluoride (RaF) and found to be one of the largest absolute values predicted so far. These calculations were performed with the complex generalised Hartree-Fock method within a two-component (quasi-relativistic) zeroth-order regular approximation framework. Peculiarities of the molecular electronic structure of RaF lead to highly diagonal Franck-Condon matrices between vibrational states of the electronic ground and first excited states, which renders the molecule in principle suitable for direct laser cooling. As a trapped gas of cold molecules offers a superior coherence time, RaF can be considered a promising candidate for high-precision spectroscopic experiments aimed at the search of molecular parity-violation effects.