Precision spectroscopy studies of radioactive molecules for fundamental physics

Precision molecular experiments provide a unique tool in the search for physics beyond the Standard Model (SM) and exploration of the fundamental forces of nature. Compared to atoms, certain molecules can offer more than eleven orders of magnitude enhanced sensitivity to violations of fundamental symmetries, enabling precision tests of the SM and the possibility to probe energy scales beyond hundreds of TeV. Containing octupole-deformed nuclei, radium monofluoride (RaF) is expected to be particularly sensitive to symmetry violating nuclear properties. In this talk, I will present the latest results obtained from a series of laser spectroscopy experiments performed on short-lived RaF molecules at the ISOLDE facility at CERN. Using a collinear resonant ionization setup, the rotational and hyperfine structure of ²²⁵RaF and ²²⁶RaF were measured with high precision. This allowed us to establish a laser cooling scheme for these molecules, and to explore nuclear structure effects at the molecular level. Our new results represent an increase in precision of almost 3 orders of magnitude compared to our previous studies, being the first of their kind performed on radioactive, short-lived molecules and opening the way for future precision studies and new physics searches in these systems.