Automatic predictions in the Georgi-Machacek model at next-to-leading order accuracy

Abstract

We study the phenomenology of the Georgi-Machacek model at next-to-leading order in QCD matched to a parton shower, using a fully automated tool chain based on MadGraph5_aMC@NLO and FeynRules. We focus on the production of the fermiophobic custodial fiveplet scalars ${H}_{5}^{0}$, ${H}_{5}^{\ifmmode\pm\else\textpm\fi{}}$, and ${H}_{5}^{\ifmmode\pm\else\textpm\fi{}\ifmmode\pm\else\textpm\fi{}}$ through vector boson fusion (VBF), associated production with a vector boson ($V{H}_{5}$), and scalar pair production (${H}_{5}{H}_{5}$). For these production mechanisms we compute next-to-leading order corrections to production rates as well as to differential distributions. Our results demonstrate that the Standard Model overall $K$-factors for such processes cannot in general be directly applied to beyond-the-Standard-Model distributions, due both to differences in the scalar electroweak charges and to the variation of the $K$-factors over the differential distributions.