Crossover from directed percolation to mean field behavior in the diffusive contact process

Recently Dantas, Oliveira and Stilck (2007 J. Stat. Mech. P08009) studied how the one-dimensional diffusive contact process crosses over from the critical behavior of directed percolation to an effective mean field behavior when the diffusion rate is sent to infinity. They showed that this crossover can be described in terms of a crossover exponent phi finding the boundaries 3 <= phi <= 4 in one spatial dimension. In the present work we re. ne and extend this result up to four spatial dimensions by means of a field-theoretic calculation and extensive numerical simulations.