It is widely believed that a new symmetry linking bosons and fermions, so-called supersymmetry exists. In order to solve the problems in the Standard Model Higgs sector, the particles predicted by the supersymmetric models should not be heavier than of the order of 1 TeV. Supersymmetry is also an integral element in attempts to unify the theories of particle physics, both if one considers the unification of Standard Model gauge couplings and if one wishesto unify all the forces of Nature, including gravity, as an essential ingredient of superstring models.

Of prime importance in supersymmetric theories is the R-parity violation and its phenomenological consequnces. Many supersymmetric models either allow explicit R-parity breaking or it is spontaneously broken in the model. The phenomenology may be quite different in R-parity preserving models. A major motivation for future accelerators is supersymmetry. Therefore, it is important to understand the phenomenological differences in the models.

Another important topic in the supersymmetric theories is the method of supersymmetry breaking. Lately an interesting possibility has emerged, namely te breaking via gauge mediation. The advantage of this method is that flavour changing interactions are naturally suppressed. Viable models and their consequences at colliders are examined.

(A short introduction to supersymmetry in Finnish is given in Basics in particle physics.)