We formulate a method of performing non-perturbative calculations in quantum field theory, based upon a derivative expansion of the exact renormalization group. We then proceed to apply this method to the calculation of critical exponents for three dimensional O(N) symmetric theory. Finally we discuss how the approximation scheme manages to reproduce some exactly known solutions in critical phenomena.
@article{arxiv.hep-th/0108031,
title = {The derivative expansion of the exact renormalization group},
author = {Michael D. Turner},
journal= {arXiv preprint arXiv:hep-th/0108031},
year = {2007}
}