Scalar Hint from the Diboson Excess?

International audienceThe possibility of testing the presence of new resonances in the Large HadronCollider (LHC) data has attracted a lot of attention after the preliminaryresults indicating possible excesses in the Run 1 data by both ATLAS and CMSCollaborations in the diboson channels, including also the more recent diphotonexcess at 750 GeV. In the following I discuss the possibility that a weaksinglet pseudo-scalar particle, η WZ , decays into two weak bosons after beingproduced in gluon fusion at the LHC. The couplings to the gauge bosons arise inthis case from a Wess-Zumino-Witten anomaly term which is calculable explicitly(not a free parameter) in models where the pseudo-scalar arises as a compositestate, as the coefficients of the anomalous couplings can be related to thefermion components of the underlying dynamics. I provide simple examples ofthese composite realisations. When such hints will be tested in more detail inthe Run 2 analyses of the LHC data it will be possible either to pinpoint inmore detail the structure of the composite electroweak sector or to give boundson it