A scalar hint from the diboson excess?
Résumé
In view of the recent diboson resonant excesses reported by both ATLAS and CMS, we suggest that a new weak singlet pseudo-scalar particle, $\eta_{WZ}$, may decay into two weak bosons while being produced in gluon fusion at the LHC. The couplings to gauge bosons can arise as in the case of a Wess-Zumino-Witten anomaly term, thus providing an effective model in which the present observed excess in the diboson channel at the LHC can be studied in a well motivated phenomenological model. In models where the pseudo-scalar arises as a composite state, the coefficients of the anomalous couplings can be related to the fermion components of the underlying dynamics. We provide an example to test the feasibility of the idea.