We investigate the structure of Polchinski’s formulation of the flow equations for the continuum Wilson effective action. Reinterpretations in terms of I.R. cutoff Green’s functions are given. A promising nonperturbative approximation scheme is derived by carefully taking the sharp cutoff limit and expanding in “irrelevancy” of operators. We illustrate with two simple models of four-dimensional λφ4 theory: the cactus approximation, and a model incorporating the first irrelevant correction to the renormalized coupling. The qualitative and quantitative behaviour give confidence in a fuller use of this method for obtaining accurate results.
International Journal of Modern Physics A
- Pub Date:
- High Energy Physics - Phenomenology;
- High Energy Physics - Theory
- 49 pages (with figures), Plain TeX, uses psfig, 7 postscript figures appended as uuencoded compressed tar file, SHEP 92/93-27, CERN-TH.6977/93, Note Added with more complete comparison to earlier work