3-DIMENSIONAL MASSIVE SCALAR FIELD-THEORY AND THE DERIVATIVE EXPANSION OF THE RENORMALIZATION-GROUP

We show that non-perturbative fixed points of the exact renormalizatio n group, their perturbations and corresponding massive field theories can all be determined directly in the continuum - without using bare a ctions or any tuning procedure. As an example, we estimate the univers al couplings of the non-perturbative three-dimensional one-component m assive scalar field theory in the Ising model universality class, by u sing a derivative expansion (and no other approximation). These are co mpared to the recent results from other methods. At order derivative-s quared approximation, the four-point coupling at zero momentum is bett er determined by other methods, but factoring this out appropriately, all our other results are in very close agreement with the most powerf ul of these methods. In addition we provide for the first time, estima tes of the n-point couplings at zero momentum, with n = 12, 14, and th e order momentum-squared parts with n = 2,..., 10. (C) 1997 Elsevier S cience B.V.