Heavy-Higgs Lifetime at Two Loops

Abstract

The Standard-Model Higgs boson with mass $M_H>>2M_Z$ decays almost exclusively to pairs of $W$ and $Z$ bosons. We calculate the dominant two-loop corrections of $O(G_F^2{M}_H^4)$ to the partial widths of these decays. In the on-mass-shell renormalization scheme, the correction factor is found to be $1+14.6$, where the second term is the one-loop correction. We give full analytic results for all divergent two-loop Feynman diagrams. A subset of finite two-loop vertex diagrams is computed to high precision using numerical techniques. We find agreement with a previous numerical analysis. The above correction factor is also in line with a recent lattice calculation.

Comments: 26 pages, 6 postscript figures. The complete paper including figures is also available via WWW at http://www.physik.tu-muenchen.de/tumphy/d/T30d/PAPERS/TUM-HEP-247-96.ps.gz