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

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 $H_5^0$, $H_5^{\pm }$, and $H_5^{\pm \pm }$ 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.

Figure 1

Differential distributions for VBF production of the $H_5^{+}$ boson, with the VBF cuts of Eq. (25) (see the text for details). The distributions for other $H_5$ states are very similar, differing primarily in overall normalization.

Figure 2

Differential distributions for $W{H}_5^{+}$ associated production, with the cuts in Eq. (28). The distributions for other $H_5$ states or for associated production with a $Z$ boson are very similar, differing primarily in overall normalization.

Figure 3

Differential distributions for $H_5^{--}{H}_5^{+}$ associated production. The distributions for other $H_5$ states are very similar, differing primarily in overall normalization.