The Standard Model has been successfully tested both at high and low energies and at present the only hint of a deviation from its predictions are the neutrino oscillations mentioned above. It is generally expected that phenomena outside the Standard Model will be found at the TeV scale, which may answer some of the above questions. However, supersymmetry also implies the existence of many additional particles, the supersymmetric partners to the known fermions and bosons. They have not been seen experimentally up to now but are searched for in present and future colliders. Experiments at high energy colliders where heavy particles like the top quark, the Higgs boson or any other new particle can be directly produced and detected.
PSI has a long tradition in searching for particle decay modes forbidden in the standard model.
The occurrence of these decays would indicate mixing among lepton families. Examples are a running experiment on muon-electron conversion , or a new project to measure the decay of the muon into a positron and a gamma ray . See also other experiments at PSI .