Electric Dipole Moment

Experimental measurements of the validity of the discrete symmetries parity P (inversion of the spatial coordinates), time reversal T and charge conjugation C (exchange of particle and antiparticle) are powerful tools to test fundamental theories like the Standard Model (SM) of the electro weak interactions. Particularly sensitive are searches for violations of one or more of the symmetries C, P and T. Many experiments are underway worldwide. Objects like permanent electric dipole moments (EDMs) of a fundamental particle, which can e.g. arise from a spatial separation of positive and negative charges in an object would violate the symmetries P and T at the same time. Thus experimental searches for a nonzero EDM are provide unique input to the theoretical model building in nature. Almost all extensions to the SM include partially broken symmetries and consequently lead to EDMs. Fundamental EDMs can experience large amplifications in larger systems like nuclei, atoms or molecules. An EDM results in a linear shift of the energy levels in an electric field. Such shifts can be measured by precision frequency measurements using atomic physics methods. A search for a nonzero EDM requires the choice of a sensitive system.