Interference in the $gg\rightarrow h \rightarrow \gamma\gamma$ On-Shell Rate and the Higgs Boson Total Width

Understand

We consider interference between the Higgs signal and QCD background in $gg\rightarrow h \rightarrow \gamma\gamma$ and its effect on the on-shell Higgs rate.

• The existence of sizable strong phases leads to destructive interference of about 2% of the on-shell cross section in the Standard Model.
• This effect can be enhanced by beyond the standard model physics.
• In particular, since it scales differently from the usual rates, the presence of interference allows indirect limits to be placed on the Higgs width in a novel way, using on-shell rate measurements.