Random Energy Model

In statistical physics of disordered systems the Random Energy Model is a toy model of a system with quenched disorder. It concerns the statistics of a system of N particles, such that the number of possible states for the systems grow as 2^N, while the energy of such states is a Gaussian stochastic variable. The model has an exact solution. Its simplicity makes this model suitable for pedagogical introduction of concepts like quenched disorder and replica symmetry.