A new search for flavor-conserving hadronic CP violation using ultracold assembled ²²³FrAg molecules

We present a new approach to search for flavor-conserving hadronic CP violation (FCH-CPV) by measuring the ²²³Fr nuclear Schiff moment. The ²²³Fr nucleus (t_1/2 = 22 minutes) is believed to have a static octupole deformation that leads to a ~300-fold enhancement in the size of its Schiff moment, for a given strength of FCH-CPV interactions [1]. The observable CP-violating energy shift induced when electrons interact with the Schiff moment is further amplified (relative to the shift in Fr atoms) when ²²³Fr is bound in a strongly ionic molecule. Binding Fr and Ag to form francium-silver (FrAg) creates such a polar molecule [2,3]. Because both species have alkali-like atomic structures, all modern atomic physics techniques such as laser cooling, controllable interactions via Feshbach resonances, and optical trapping can be applied to them. This will enable the assembly of ultracold ²²³FrAg molecules using well-established methods [4]. Assuming experimental parameters for molecule number, nuclear spin coherence time, and detection efficiency that have already been demonstrated in other experiments that use ultracold assembled molecules, we project a factor of ~1000 improvement in underlying FCH-CPV physics for the first generation of an experiment. In this talk, we present progress towards creating ²²³FrAg by demonstrating magneto-optical trapping of silver atoms and studies towards measuring ultracold Ag-Ag scattering properties. We also present progress towards developing an offline ²²³Fr source.

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[2] Fleig, T., & DeMille, D. (2021). Theoretical aspects of radium-containing molecules amenable to assembly from laser-cooled atoms for new physics searches. New J. Phys., 23(11), 113039.

[3] Śmiałkowski, M., & Tomza, M. (2021). Highly polar molecules consisting of a copper or silver atom interacting with an alkali-metal or alkaline-earth-metal atom. Phys. Rev. A, 103(2), 022802.

[4] Kłos, J., et al. (2022). Prospects for assembling ultracold radioactive molecules from laser-cooled atoms. New J. Phys., 24(2), 025005.