Traces of a triboson resonance

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 (Y0) or charged (Y±) particles, namely R → Y0 W, with Y0 → ZX, or R → Y± Z, with Y± → WX. An obvious candidate for such intermediate particle is a neutral one Y0, given a 3.9σ 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.