Abstract
We present a systematic comparison of doubly charged Higgs boson production mechanisms at hadron colliders in the context of the Type II Seesaw model, emphasizing the importance of higher-order corrections and subdominant channels. We consider the Drell-Yan channel at next-to-leading order in QCD, photon fusion at leading order, gluon fusion with resummation of threshold logarithms up to next-to-next-to-next-to-leading logarithmic accuracy, and same-sign weak boson fusion at next-to-leading order in QCD. For Drell-Yan processes, we study the impact of a static jet veto at next-to-leading order matched to the resummation of jet veto scale logarithms at next-to-next-to-leading logarithmic accuracy. For the photon fusion channel, the dependence on modeling photon parton distribution functions is definitively assessed. To model vector boson fusion at next-to-leading order, we include all interfering topologies at $\mathcal{O}(\alpha^4)$ and propose a method for introducing generator-level cuts within the MC@NLO formalism. Our results are obtained using a Monte Carlo tool chain linking the \textsc{FeynRules}, \textsc{NloCT} and \textsc{MadGraph5\_aMC@NLO} programs and have necessitated the development of new, publicly available, Universal FeynRules Output libraries that encode the interactions between the Type II Seesaw scalars and Standard Model particles. Libraries are compatible with both the normal and inverted ordering of Majorana neutrino masses.
Highlights
The type II seesaw mechanism hypothesizes extending the Standard Model (SM) of particle physics by a single scalar multiplet Δin the ð1; 3Þ1 representation its SUð3Þc × SUð2ÞL × Uð1ÞY gauge symmetry [1,2,3,4,5]
For the Drell-Yan process, we study the impact of a static jet veto at next-to-leading order matched to the resummation of jet veto scale logarithms at next-to-next-to-leading logarithmic accuracy
We note that when the above procedure is matched to parton showers that support QED and photon parton distribution functions (PDFs) evolution, such as PYTHIA8,8 initial-state photons can be matched to initial-state q → qγà splittings
Summary
The type II seesaw mechanism hypothesizes extending the Standard Model (SM) of particle physics by a single scalar multiplet Δin the ð1; 3Þ1 representation its SUð3Þc × SUð2ÞL × Uð1ÞY gauge symmetry [1,2,3,4,5]. Both the ATLAS and CMS collaborations report 95% confidence level (CL) exclusion limits on triplet scalar masses up to about 400 GeV in multileptonic channels [39,40] and about 200 GeV in bosonic channels [41], assuming a degenerate mass spectrum Most of these works extract their sensitivity or exclusion limits from leading-order (LO) descriptions matched with parton showers, and consider ΔÆÆΔÆ associated production or ΔþþΔ−− pair production via the charged current (CC) and neutral current (NC) Drell-Yan (DY) mechanisms i.e., quark-antiquark annihilation. Studies and searches for type II scalars using these tools are blind to significant, qualitative differences in jet activity between triplet scalar signal events and the leading background processes, and cannot reliably exploit selection cuts that discriminate e.g., jet vetoes This is noteworthy as recent investigations show that event-based jet vetoes can substantially increase the discovery prospects of anomalous multileptonic events [48,49,50]. The triplet Yukawa Lagrangian is given by LYΔ 1⁄4 −YΔL · Δ L þ H:c:; ð2:5Þ
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