The Search for Electric Dipole Moments of Charged Particles in Storage Rings

Permanent electric dipole moments (EDMs) of charged particles are a sensitive probe of physics beyond the Standard Model and are directly related to additional sources of CP violation that may explain the matter-antimatter asymmetry of the universe. In storage-ring experiments, the EDM of a charged particle is accessed by measuring a small tilt of the invariant spin axis relative to the plane of the ring. In this contribution, an experimental determination of the invariant spin axis at the COoler SYnchrotron (COSY), performed using an radio frequency Wien filter in combination with a superconducting Siberian snake and the 2 MV electron-cooler solenoid, is presented. The observed tilts are of the order of a few milliradians and are dominated by systematic effects which are currently under investigation. This result demonstrates the feasibility of EDM searches using storage rings and provides a basis for future dedicated facilities.