Fully automated precision predictions for heavy neutrino production mechanisms at hadron colliders

Abstract

Motivated by TeV-scale neutrino mass models, we propose a systematic treatment of heavy neutrino ($N$) production at hadron colliders. Our simple and efficient modeling of the vector boson fusion (VBF) ${W}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\gamma}\ensuremath{\rightarrow}N{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}$ and $N{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}+nj$ signal definitions resolve collinear and soft divergences that have plagued past studies, and is applicable to other color-singlet processes, e.g., associated Higgs $({W}^{\ifmmode\pm\else\textpm\fi{}}h)$, sparticle $({\stackrel{\texttildelow{}}{\ensuremath{\ell}}}^{\ifmmode\pm\else\textpm\fi{}}\stackrel{\texttildelow{}}{{\ensuremath{\nu}}_{\ensuremath{\ell}}})$, and charged Higgs $({h}^{\ifmmode\pm\else\textpm\fi{}\ifmmode\pm\else\textpm\fi{}}{h}^{\ensuremath{\mp}})$ production. We present, for the first time, a comparison of all leading $N$ production modes, including both gluon fusion (GF) $gg\ensuremath{\rightarrow}{Z}^{*}/{h}^{*}\ensuremath{\rightarrow}N\stackrel{(\ensuremath{-})}{{\ensuremath{\nu}}_{\ensuremath{\ell}}}$ and VBF. We obtain fully differential results up to next-to-leading order (NLO) in QCD accuracy using a Monte Carlo tool chain linking feynrules, nloct, and madgraph5_amc@nlo. Associated model files are publicly available. At the 14 TeV LHC, the leading order GF rate is small and comparable to the NLO $N{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}+1j$ rate; at a future 100 TeV Very Large Hadron Collider, GF dominates for ${m}_{N}=300--1500\text{ }\text{ }\mathrm{GeV}$, beyond which VBF takes the lead.