Observing Strongly Interacting Vector Boson Systems at the CERN Large Hadron Collider

TL;DR

The study evaluates the LHC’s ability to access strongly interacting electroweak symmetry breaking through weak boson scattering in VVjj final states. It compares two unitarization paradigms—a heavy scalar resonance and a Warped Higgsless model with vector KK resonances—using exact tree-level matrix elements and double forward jet tagging to optimize signal over backgrounds. The analysis shows that, after tailored inclusive and VBF cuts plus leptonic selections, observable excesses can appear in multiple channels (notably ZZjj and WWjj for scalars, and WZjj/WWjj for KK vectors), enabling discrimination between scalar and vector mechanisms. The work highlights the practical potential of central jet veto enhancements and multi-channel strategies for probing strong EWSB at the LHC with realistic luminosities.

Abstract

We explore the potential of the CERN Large Hadron Collider to access a strongly interacting electroweak symmetry breaking sector via weak boson scattering with WWjj, ZZjj and WZjj final states. As examples of models with scalar or vector resonances we concentrate on a scenario with a heavy Higgs boson and on a Warped Higgsless Kaluza-Klein model of narrow spin-one resonances. The signal and the most prominent background processes are evaluated using exact tree-level matrix elements including full off-shell and finite width effects for final states with two tagging jets and four leptons. Using double forward jet-tagging techniques, we derive dedicated cuts on the observable jets and charged leptons to suppress Standard Model backgrounds. We demonstrate that the LHC has substantial sensitivity to strong interactions in the electroweak symmetry breaking sector.

Figures (6)

• Figure 1: Examples of Feynman-graph topologies contributing to EW $W^+W^-jj$ production at $\mathcal{O}(\alpha^6)$.
• Figure 2: Modified weak boson fusion topology. The shaded area contains different Kaluza-Klein intermediate states.
• Figure 7: Invariant mass distribution of the two charged leptons (a) and cluster transverse mass distribution of the $W^{+}W^{-}$ system (b) for the $pp \rightarrow W^{+}W^{-} jj$ process after imposing all levels of cuts.
• Figure 8: Invariant mass distribution of the four charged leptons (a) and of the two tagging jets (b) for the $pp \rightarrow ZZ jj \rightarrow 4\ell\,jj$ process after imposing all levels of cuts.
• Figure 9: Invariant mass distribution of the two tagging jets (a) and cluster transverse mass distribution of the $ZZ$ system (b) for the $pp \rightarrow ZZ jj\rightarrow 2\ell 2\nu\,jj$ process after imposing all levels of cuts.