A new simple version of the replica method

The moments of the partition function of a disordered system are used to de termine the probability distribution of the free energy. The relation betwe en them is essentially given by a Legendre transformation. A cut-off must b e introduced to ensure the normalization of the distribution function. The method yields reasonable approximations or even rigorous results for the me an free energy without taking into account replica symmetry breaking (RSB). It therefore represents a conceptually and technically simple alternative to Parisi's RSB-scheme. Investigated examples are the random-energy model a nd the Sherrington-Kirkpatrick model of spin glasses.