Searching for Fundamental Symmetry Violation with Cold YbOH Molecules

Heavy, polar molecules in the gas-phase are sensitive experimental probes of symmetry violating physics beyond the Standard Model (BSM). The large internal fields in these molecules amplify the effects of possible Parity (P) and Time reversal (T) violating observables, such as the electron’s electric dipole moment (eEDM) or a nuclear magnetic quadrupole moment (NMQM). Recent eEDM measurements in a cold molecular beam, by the ACME Collaboration, constrain P,T violating leptonic physics at the 10 TeV scale. Molecular beam measurements of a NMQM would provide a complimentary probe in the hadronic sector. Additionally, molecular laser-cooling and trapping can improve coherence times and extend leptonic and hadronic constraints to PeV energies. Our lab is currently constructing two experiments to probe BSM physics in YbOH, a laser-coolable, polyatomic molecule. One experiment is a measurement on a cold beam of  ¹⁷³YbOH, which is sensitive to the NMQM of the ¹⁷³Yb nucleus. The second experiment seeks to cool and trap ¹⁷⁴YbOH, enabling measurements of the eEDM with significantly enhanced sensitivity. We present progress on the prerequisite spectroscopic study of YbOH, including characterization of the origin band of ¹⁷³YbOH and the vibronically perturbed excited states of ¹⁷⁴YbOH.