Rare decays of neutral kaons

This report summarises results on rare decays of neutral kaons. Three different classes of decays are discussed. Most of the examples were taken from results of the NA31 experiment. Therefore, the experiment is described in the first chapter. Subject of the second chapter are decays allowing to measure the CP-violation (i.e. $K_{L} \to \pi^{0}e^{+}e^{−}$) and some related decays (i.e. $K_{L} \to \gamma\gamma e^{+}e^{−}$ as the worst background process to $K_{L} \to \pi^{0}e^{+}e^{−}$). In the third chapter searches for decays which are forbidden or highly suppressed in the Standard model are discussed. The forth chapter describes the measurements of decays allowing to test low energy QCD. The last chapter lists the prospects for the future of studying rare decays of neutral kaons.