Skip to Content

Is the electron round?

We have made a new measurement of the electron’s electric dipole moment (EDM) using a beam of YbF molecules. [1] [2] By measuring atto-eV energy shifts in a molecule, this experiment probes new physics at the tera-eV energy scale. According to the standard model, this EDM is dₑ ≈10 -38 e. cm – some eleven orders of magnitude below the current experimental limit. However, most extensions to the standard model predict much larger values, potentially accessible to measurement [3] .  Hence, the search for the electron EDM is a search for physics beyond the standard model. I will describe our experimental method, our current results and their implications for particle physics.  I will also outline the prospects for further major improvement in sensitivity.



[1] J. J. Hudson, D. M. Kara, I. J. Smallman, B. E. Sauer, M. R. Tarbutt, E. A. Hinds, “Improved measurement of the shape of the electron”, Nature 473 , 493 (2011). doi:10.1038/nature10104

[2] D.M. Kara, I.J. Smallman, J.J. Hudson, B.E. Sauer, M.R. Tarbutt, and E.A. Hinds, “Measurement of the electron's electric dipole moment using YbF molecules: methods and data analysis”,  N. J. P . 14 103051 (2012).

[3] E. D. Commins, Electric dipole moments of leptons , in Advances in Atomic, Molecular, and Optical Physics, Vol. 40, B. Bederson and H.Walther (Eds.), Academic Press, New York, pp. 1-56 (1999).

HInds: Graphic 1
HInds: Graphic 1
Hinds: Graphic 2
Hinds: Graphic 2