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 ($Y^0$) or charged ($Y^{\pm }$) particles, namely $R\to Y^{0}W$, with $Y^0\to ZX$, or $R\to Y^{\pm }Z$, with $Y^{\pm }\to WX$. 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.

Comments: LaTeX 32 pages, 38 figures. v2: Figs. 6, 9 and 11 modified. v3: added VH search in hadronic final state. v4: final published version