Heavy Higgs-boson lifetime at two loops

Abstract

The standard-model Higgs boson with a mass ${M}_{H}\ensuremath{\gg}2{M}_{Z}$ 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 $1+14.6%{({M}_{H}/\mathrm{TeV})}^{2}+16.9%{({M}_{H}/\mathrm{TeV})}^{4}$, 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.