NEMESIS · Neutron Experiments join Muon Experiments for Synergy in Investigation and Search for new physics

NEMESIS aims to conduct groundbreaking, high-sensitivity searches for particle physics Beyond the Standard Model (BSM) by combining the high-intensity frontiers of muons and ultracold neutrons while developing a new generation of detectors and high-intensity beams. This goal is pursued by strengthening and expanding the collaboration between EU, Swiss, and US researchers across three international laboratories: FNAL and BNL in the United States, and PSI in Switzerland. The search for the still unobserved Charged Lepton Flavour Violation (cLFV) processes in the muon sector will be pursued at Mu2e at FNAL and MEG-II and Mu3e at PSI, utilising the most intense muon sources available worldwide. The synergy among these experiments significantly enhances the discovery potential, improving sensitivity by up to four orders of magnitude to explore mass scales up to 10^4 TeV across most BSM models. This partnership also strengthens the physics interpretation should a cLFV discovery occur. PSI beams will be leveraged to enhance current measurements of the Electric Dipole Moment (EDM) by several orders of magnitude in both muon and neutron systems. muEDM will employ the new frozen-spin technique, while n2EDM will utilise high-intensity, ultra-cold neutrons. NEMESIS, playing a leading role in both experiments, will combine expertise and efforts to precisely determine the EDM. A non-zero value would provide unambiguous evidence of new physics related to the origin of the matter-antimatter asymmetry of the Universe. An ambitious platform for studying novel beam generation and detector technologies is also planned across the network, focusing on the development of innovative silicon and gas detectors and improving the handling, monitoring, and quality of high-intensity muon and cold neutron beams. The project’s innovations will extend to higher energy and intensity fields and beyond particle physics, with applications in material science, medical physics, and homeland security.