The Standard Model of particle physics is known to be incomplete. Extensions to the Standard Model, 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 electron electric dipole moment (EDM), d(e), in the range of 10(-27) to 10(-30) e·cm. The EDM is an asymmetric charge distribution along the electron spin (S(→)) that is also asymmetric under T. Using the polar molecule thorium monoxide, we measured d(e) = (-2.1 ± 3.7stat ± 2.5syst) × 10(-29) e·cm. This corresponds to an upper limit of |d(e)| < 8.7 × 10(-29) e·cm with 90% confidence, an order of magnitude improvement in sensitivity relative to the previous best limit. Our result constrains T-violating physics at the TeV energy scale.

Calculations of Stark interference between E1 and M 1 transition amplitudes on the H 3 ∆1 to C 1 Π transition in ThO is performed. Calculations are required for estimations of systematic errors in the experiment for electron electric dipole (eEDM ) moment search due to imperfections in laser beams used to prepare the molecule and read out the eEDM signal.

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Precision searches for time-reversal symmetry violating interactions in polar molecules are extremely sensitive probes of high energy physics beyond the standard model. To extend the reach of these probes into the PeV regime, long coherence times and large count rates are necessary. Recent advances in laser cooling of polar molecules offer one important tool-optical trapping. However, the types of molecules that have been laser cooled so far do not have the highly desirable combination of features for new physics searches, such as the ability to fully polarize and the existence of internal comagnetometer states. We show that by utilizing the internal degrees of freedom present only in molecules with at least three atoms, these features can be attained simultaneously with molecules that have simple structure and are amenable to laser cooling and trapping. DOI: 10.1103/PhysRevLett.119.133002 Precision measurements of heavy atomic and molecular systems have proven to be a powerful probe of high energy scales in the search for new physics beyond the standard model (BSM) [1]. For example, the limit on the electron's electric dipole moment (EDM), set by the ACME Collaboration using ThO, is sensitive to T-violating BSM physics at the ≳TeV scale [2]. This sensitivity relies on the ability to experimentally access the large effective electromagnetic fields (>10 GV=cm) present in heavy polar molecules by fully polarizing them in the laboratory frame. This makes the experimental challenges of working with such a complex species worth the effort.Despite the success of ACME, a current limitation of that experiment and all present molecular beam experiments is that their coherence time is limited to a few milliseconds by the beam transit time through an apparatus of reasonable size. Since EDM sensitivity scales linearly with coherence time, trapping neutral molecules has the potential to increase sensitivity by many orders of magnitude. Trapped molecular ions have shown great power in EDM searches [3], primarily due to their long coherence time of ∼1 s. Neutral species offer the ability to increase the number of trapped molecules much more easily and essentially without limit compared to ions, while retaining strong robustness against systematic errors. Here we show that laser-cooled and trapped polyatomic molecules offer a combination of features not available in other systems, including long lifetimes, robustness against systematic errors, and scalability, and present a feasible approach to access PeV-scale BSM physics.A very promising route to trapping EDM-sensitive molecules is direct laser cooling and trapping from cryogenic buffer gas beams (CBGBs), which has advanced tremendously in the last few years [4][5][6][7][8][9][10][11]. The molecules that have been cooled so far posses an electronic structure that makes them amenable to laser cooling, but also precludes the existence of Ω doublets, such as the 3 Δ 1 molecular state used in the two most sensitive electron EDM measurements [2,3]. These doublets enable full po...