Non-Gaussian corrections to higgs mass in autonomous λφ {3+1/4}

Recent calculations in one-loop and Gaussian approximation, using the so-called autonomous renormalization scheme, indicate a comparatively massive, narrow Higgs excitation at about 2 TeV. Here I show that this result persists in the framework of a post-Gaussian variational approximation for the pure O(N)-symmetric φ⁴-theory for N>1. The method is based on nonlinear transformations of path-integral variables, and the optimization amounts to a Schwinger-Dyson-type summation of diagrams. In the case of O(4), for example, I find M _Higgs=2.3 TeV, compared with 1.9 TeV and 2.1 TeV in one-loop and Gaussian approximation, respectively. My results are also consistent with the Consoli-Stevenson conjecture that the Gaussian and one-loop results for N=1 are exact and may even hold for general N.