Description
We present a new approach to search for hadronic CP violation by measuring the $^{223}$Fr nuclear Schiff moment in ultracold assembled FrAg (francium silver) molecules. The $^{223}$Fr nucleus is known to have octupole deformation that leads to a factor of ~300 enhancement in the size of its Schiff moment for a given strength of CP-violating hadronic 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 $^{223}$Fr is bound in a strongly ionic molecule that produces a large internal electric field. Binding Fr and Ag forms such a polar molecule [2,3]. Furthermore, both atoms have alkali-like atom structures, making them accessible to laser cooling, controllable interactions via Feshbach resonances, and optical trapping. Recent calculations have shown that the FrAg electronic structure is highly amenable to optical transfer of molecules from weakly-bound magneto-associated “Feshbach molecule” states, into the rovibronic ground state [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 CP-violating physics for the first generation of an experiment with $^{223}$FrAg. Work is underway to form a magneto-optic trap of silver and then study ultracold Ag-Ag scattering properties. We also present plans to laser cool francium using an offline source.
[1] Spevak, V., Auerbach, N., & Flambaum, V. V. (1997). Enhanced T-odd, P-odd electromagnetic moments in reflection asymmetric nuclei. Physical Review C, 56(3), 1357.
[2] Fleig, T., & DeMille, D. (2021). Theoretical aspects of radium-containing molecules amenable to assembly from laser-cooled atoms for new physics searches. New Journal of Physics, 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. Physical Review A, 103(2), 022802.
[4] Kłos, J., Li, H., Tiesinga, E., & Kotochigova, S. (2022). Prospects for assembling ultracold radioactive molecules from laser-cooled atoms. New Journal of Physics, 24(2), 025005.
| Presenter name | Mohit Verma |
|---|---|
| How will you attend ICAP-27? | I am planning on in-person attendance |
