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.
Highlights
Source may well be different from the specific signature searched for
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 W Z plus an extra particle X
In the LHC Run 1 at a centre-of-mass (CM) energy of 8 TeV the most remarkable deviation from the SM prediction was a 3.4σ excess found by the ATLAS Collaboration [1] in the search for heavy resonances decaying into two SM gauge bosons V = W/Z — known as diboson resonances — with the bosons decaying hadronically, giving rise to two fat jets J
Summary
The ATLAS Collaboration found a 3.4σ excess in Run 1 data at 8 TeV with a luminosity of 20.3 fb−1. In order to explain the cleaning up of the bump in Run 2 data without resorting to large statistical fluctuations, a new physics signal would be required for which (i) the combination of cuts on jet the efficiency; (ii) but the cmoamsbs,inDat2ioanndofNcturktsfoornRje=t m1.a0ssj,et√s yinaRndunN2trskefvoerreRly decreases = 1.2 jets in Run 1 does not In this regard, we have explored in appendix B several W ZX triboson signals in several phase space regions and have found that, after the application of the remaining boson tagging cuts, the effect of the Ntrk cut is very similar for the Run 1 and Run 2 analyses. Effect in jet substructure variables, perhaps in Ntrk; (ii) some new physics signal far more complex than a triboson, in which case one would have to justify why the excesses seen in the ATLAS searches are localised
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