Colloquium Seminar: Search for a static or oscillating electric dipole moment of the neutron at PSI
Speaker: Philipp Schmidt-Wellenburg, PSI
Why is there so much matter and even more dark matter and so little anti-matter observed in our Universe? One necessary condition to create a matter/antimatter asymmetric universe from symmetric starting conditions is a sufficiently strong source of charge/parity violation (CPV) in the fundamental physics describing the early Universe, while Axion like particles are viable dark matter candidates. A discovery of a permanent nEDM value larger than the SM prediction (< 1e-31ecm) would be an indication for a yet unknown source of CPV and might help to explain the matter/antimatter asymmetry of the Universe, or shed light on to the strong CP problem. While a discovery of an oscillating nEDM would be the signal of an Axion background field coupling to the QCD theta term. At the Paul Scherrer Institute (PSI) in Switzerland a collaboration of 15 institutions is searching for an nEDM using ultracold neutrons (UCN). We intend to either discover an EDM or improve the current upper limit, dn < 3e-26ecm @90% C.L. [J.M. Pendlebury et al. PRD 92, 092003 (2015)], by using the same but improved and upgraded spectrometer connected to the solid-deuterium-based UCN source at PSI. Data taking has concluded in end of 2016 at PSI, while this year was dedicated for the analysis and the study of possible systematic effects. In my talk I will first discuss the applied methods and techniques and then present the current status of analysis and new results.