We report on a new measurement of the CP-violating permanent Electric Dipole Moment (EDM) of the neutral $^{ 129}$Xe atom. Our experimental approach is based on the detection of the free precession of co-located nuclear spin-polarized $^3$He and $^{ 129}$Xe samples. The EDM measurement sensitivity benefits strongly from long spin coherence times of several hours achieved in diluted gases and homogeneous weak magnetic fields of about 400~nT. A finite EDM is indicated by a change in the precession frequency, as an electric field is periodically reversed with respect to the magnetic guiding field. Our result, $\left(-4.7\pm6.4\right)\cdot 10^{ -28}$ ecm, is consistent with zero and is used to place a new upper limit on the $^{ 129}$Xe EDM: $|d_\text{ Xe}|<1.5 \cdot 10^{ -27}$ ecm (95% C.L.). We also discuss the implications of this result for various CP-violating observables as they relate to theories of physics beyond the standard model.
Categories: physics.atom-ph