Order of Magnitude Smaller Limit on the Electric Dipole Moment of the Electron

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Science  19 Dec 2013:
DOI: 10.1126/science.1248213

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The Standard Model (SM) of particle physics is known to be incomplete. Extensions to the SM, such as weak-scale Supersymmetry, posit the existence of new particles and interactions that are asymmetric under time-reversal (T), and nearly always predict a small, yet potentially measurable (10−27-10−30 e cm) electron electric dipole moment (EDM, (EDM, Embedded Image). The EDM an asymmetric charge distribution along the spin (Embedded Image) that is also asymmetric under T. Using the polar molecule thorium monoxide (ThO), we measure Embedded Image = (–2.1 ± 3.7stat ± 2.5syst) × 10−29 e cm. This corresponds to an upper limit of Embedded Image < 8.7 × 10−29 e cm with 90 percent confidence, an order of magnitude improvement in sensitivity compared to the previous best limit. Our result constrains T-violating physics at the TeV energy scale.

  • * The collaboration consists of all listed authors. There are no additional collaborators.

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