# The 27th International Conference on Atomic Physics

17-22 July 2022
Royal Conservatory of Music, Toronto
America/Toronto timezone

## Systematic effects in eEDM searches with BaF

19 Jul 2022, 17:00
1h 30m
Hart House (Hart House)

### Hart House

#### Hart House

7 Hart House Cir, Toronto, ON M5S 3H3
Poster presentation Precision measurement and tests of fundamental physics

### Description

A promising way to explore physics beyond the Standard Model of particle physics is doing high-precision measurements on molecules. One such measurement is the search for the P,T-violating electric dipole moment of the electron (eEDM). In diatomic molecules with one heavy atom, the effect of the eEDM is expected to be strongly enhanced, because of small rotational splittings and an enhanced electron density near a highly charged nucleus, with currently the best limit of $d_e<1.1×10^{-29}$ e cm measured in ThO [1]. In the NL-eEDM collaboration, the eEDM induced contribution to the ground state of BaF is investigated [2]. The eEDM manifests itself as an extra splitting between the magnetic substates due to the electric field, in addition to the Zeeman effect in magnetic fields. To measure the effect of a possible eEDM, a spin precession experiment is set up in well-controlled electric and magnetic fields. We use a two-photon transition to create a superposition of two hyperfine substates. In the magnetic and electric field, a phase difference between the two hyperfine states is accumulated, which has an extra contribution due to the electric field if the eEDM exists. The contributions to this phase from known-physics, in particular from the magnetic moment, require understanding of the molecular structure. The derived value for the eEDM is limited by statistics and the understanding of systematic effects.
To increase the statistical sensitivity, an intense source of ultracold BaF molecules will be used, produced in a cryogenic source. The molecules will be transversely laser cooled and decelerated with a Stark decelerator [3].
To have control over the systematics, it is crucial to understand how the eEDM signal depends on the experimental parameters, such as the magnetic field and laser intensities. For this we developed a description of the dynamics of our spin-precession experiment, based on the Optical Bloch Equations. With this tool we can calculate to which precision we need to control and measure the experimental parameters during the experiment.

[1] ACME Collaboration. Improved limit on the electric dipole moment of the electron, Nature 562, 355–360 (2018).
[2] The NL-eEDM collaboration., Aggarwal, P., Bethlem, H.L. et al. Measuring the electric dipole moment of the electron in BaF. Eur. Phys. J. D 72, 197 (2018).
[3] P. Aggarwal, Y. Yin, K. Esajas, H. L. Bethlem, A. Boeschoten, A. Borschevsky, S. Hoekstra, K. Jungmann, V. R. Marshall, T. B. Meijknecht, M. C. Mooij, R. G. E. Timmermans, A. Touwen, W. Ubachs, and L. Willmann (NL−eEDMCollaboration) Phys. Rev. Lett. 127, 173201

Presenter name Boeschoten, Alexander I am planning on in-person attendance

### Primary authors

Alexander Boeschoten (Van Swinderen Institute) Prof. Hendrick L. Bethlem (LaserLab, VU, Amsterdam) Prof. Anastasia Borschevsky (Van Swinderen Institute, University of Groningen) Prof. Steven Hoekstra (Van Swinderen Institute, University of Groningen) Mr Joost W.F. van Hofslot (Van Swinderen Institute, University of Groningen) Prof. Klaus Jungmann (Van Swinderen Institute, University of Groningen) Ms Virginia Marshall (Van Swinderen Institute, University of Groningen) Mr Thomas B. Meijknecht (Van Swinderen Institute, University of Groningen) Mr Maarten C. Mooij (LaserLab, VU, Amsterdam) Prof. Rob G.E. Timmermans (Van Swinderen Institute, University of Groningen) Mr Anno Touwen (Van Swinderen Institute, University of Groningen) Prof. Wim Ubachs (LaserLab, VU, Amsterdam) Prof. Lorenz Willmann (Van Swinderen Institute, University of Groningen)

### Presentation Materials

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