Force correlations and arch formation in granular assemblies

In the context of a simple microscopic schematic scalar model we study the effects of spatial correlations in force transmission in granular assemblies. We show that the parameters of the normalized weight distribution function, P(nu) similar to nu(alpha) exp(-nu/phi), strongly depend on the spatial extensions, xi(V), of such correlations. In particular , we evaluate the functions phi(xi(V)) and alpha(xi(V)) . If xi(V) --> infinity then phi similar to xi(V) and weights are power law distributed.