New Upper Limit on the Electron's Electric Dipole Moment

The ACME collaboration has measured the electron's electric dipole moment (eEDM) to be $d_e = (-2.1 \pm 3.7_{\mathrm{stat}} \pm 2.5_{\mathrm{syst}}) \times 10^{-29} \; e \cdot \mathrm{cm}$ [1,2]. This corresponds to an upper limit of $|d_e| < 8.7 \times 10^{-29} \; e \cdot \mathrm{cm}$ with 90 percent confidence, which represents an order of magnitude improvement on the previous best limit [3]. We describe our method of measuring the eEDM using a buffer gas cooled beam of thorium monoxide (ThO) and discuss our approach to finding and quantifying systematic effects. This results constrains T-violating physics at the TeV energy scale.\\[4pt] [1] The ACME Collaboration, \emph{Science} \textbf{343}, (2014) 269--272.\\[0pt] [2] L.~V.~Skripnikov, A.~N.~ Petrov, and A.~V.~Titov, \emph{J.~Chem.~Phys.} \textbf{139}, (2013) 221103.\\[0pt] [3] J.~J.~Hudson, D.~M.~Kara, I.~J.~Smallman, B.~E.~Sauer, M.~R.~Tarbutt, and E.~A.~Hinds, \emph{Nature} \textbf{473}, (2011) 493--496.