On the fixed-point structure of PHI4 theory in four dimensions

A real space renormalization of PHI4 theory is performed. Starting with different values of the bare PHI4-coupling on lattice size 164 at the critical point block-spin transformations to size 84 and 44 are performed. The values of the corresponding coupling constants for 24 types of even interactions are determined following a method recently proposed by Swendsen. It turns out that already after 2 block-spin transformations the theories are very close to each other. The fixed point appears to be independent of the bare PHI4-coupling and of gaussian nature. (orig.)