Renormalization group for spin glasses

A renormalization group transformation suitable for spin glasses, and more generally for disordered systems, is prsented. The approach is non-standard for two reasons. 1. The coarse graining transformation is performed on the distribution of site overlaps, which clearly is not a. Boltzmann-Gibbs dis tribution. 2. The additional interactions are realized introducing a gauge- field disorder distribution, while the Hamiltonian is kept fixed. Universal ity classes are thus naturally defined on a large set of models, going from Zz and Gaussian spin glasses to Ising and fully frustrated models, and oth ers. The role of frustration and of the deconfinement transition can also b e analysed in terms of fixed points. The proposed analysis is tested numeri cally on the Z(3) Edwards-Anderson model in d = 4. Good estimates of the cr itical index nu and of T-c are obtained, and an RG flow diagram is sketched for the first time.