Traces of a triboson resonance

TL;DR

This paper proposes that certain excesses in high-mass diboson searches can be explained by a new triboson resonance involving an additional particle, suggesting new decay channels and discovery strategies.

Contribution

It introduces a novel triboson resonance model that accounts for observed excesses and null results, expanding the understanding of potential new physics signals.

Findings

Compatibility of excesses with a triboson decay model

Identification of candidate intermediate particles like $Y^0$

Strategies for discovering triboson resonances with existing searches

Abstract

We show that the relatively small but coincident excesses observed around 2 TeV in the ATLAS Run 1 and Run 2 hadronic diboson searches --- when a cut on the number of tracks in the fat jets is not applied --- and the null results of all remaining high-mass diboson searches are compatible with the decay of a triboson resonance $R$ into $WZ$ plus an extra particle $X$. These decays can take place via new neutral ($Y^0$) or charged ($Y^\pm$) particles, namely $R \to Y^0 \, W$, with $Y^0 \to Z X$, or $R \to Y^\pm Z$, with $Y^\pm \to W X$. An obvious candidate for such intermediate particle is a neutral one $Y^0$, given a $3.9\sigma$ excess found at 650 GeV by the CMS Collaboration in searches for intermediate mass diboson resonances decaying to $ZV$, with $V=W,Z$. We discuss discovery strategies for triboson resonances with small modifications of existing hadronic searches.