Comparison of perturbative RG theory with lattice data for the 4d Ising model

Predictions for (phi(4))(4) theory from renormalization-group-improved perturbation theory, as formulated by Luscher and Weisz, are compared to published (and some unpublished) data from lattice Monte Carlo simulations of the 4-dimensional Ising model. Good agreement is found in all but one respect: the change in the wavefunction-renormalization constant (Z) over cap (R) across the phase transition is significantly greater than predicted. A related observation is that propagator data in the broken phase show deviations from free-propagator form-cleviations that become larger, not smaller, closer to the continuum limit. More data closer to the critical point are needed to clarify the situation. (c) 2005 Elsevier B.V. All rights reserved.