Anatomy of the ATLAS diboson anomaly

Abstract

We perform a general analysis of new physics interpretations of the recent ATLAS diboson excesses over Standard Model expectations in LHC Run I collisions. Firstly, we estimate a likelihood function for the true signal in the $WW$, $WZ$, and $ZZ$ channels, finding that the maximum has zero events in the $WZ$ channel, though the likelihood is sufficiently flat to allow other scenarios. Secondly, we survey the possible effective field theories containing the Standard Model plus a new resonance that could explain the data, finding just two possibilities, viz., a vector that is either a left- or right-handed $SU(2)$ triplet. Finally, we compare these models with other experimental data and determine the parameter regions in which they provide a consistent explanation.