Radioactive molecules for fundamental physics

Possessing a large sensitivity to violations of the fundamental symmetries of nature, certain molecules can be engineered to answer some of the biggest open questions in physics, such as the origin of the matter-antimatter asymmetry and the nature of Dark Matter. Radioactive molecules containing octupole-deformed nuclei, such as radium monofluoride (RaF), are expected to be particularly sensitive to symmetry-violating nuclear properties and can probe energy scales beyond hundreds of TeV. In this talk, I will present pioneering results in the study of radioactive molecules obtained from a series of laser spectroscopy experiments performed on short-lived RaF molecules at the ISOLDE facility at CERN. These measurements allowed us to establish a highly effective laser cooling scheme for these molecules and to observe, for the first time, the effects of minuscule electroweak nuclear effects on the molecular energy levels. These results opened the way for future precision studies and new physics searches using radioactive molecules. I will then discuss ongoing efforts in developing a novel precision experiment to measure parity-violating nucleon-nucleon weak interactions using single molecular ions inside a Penning trap. This technique is predicted to provide enhancements in the sensitivity to the sought-for signals of more than 12 orders of magnitude compared to atoms. The method is particularly suited for radioactive species, which can often be produced only in minuscule amounts, but where the signal is expected to be significantly enhanced.