Effective potential for scalar λϕ4 theory is obtained using the exact renormalization group method which includes both the usual one-loop contribution as well as the dominant higher loop effects. Our numerical calculation indicates a breakdown of naive one-loop result for sufficiently large renormalized coupling constant.
@article{arxiv.hep-th/9404086,
title = {Renormalization Group Approach to Scalar Theory},
author = {Sen-Ben Liao and Chengqian Gong},
journal= {arXiv preprint arXiv:hep-th/9404086},
year = {2009}
}