Drell-Yan production of multi $Z'$-bosons at the LHC within Non-Universal ED and 4D Composite Higgs Models

International audienceThe Drell-Yan di-lepton production at hadron colliders is by far thepreferred channel to search for new heavy spin-1 particles. Traditionally, suchsearches have exploited the Narrow Width Approximation (NWA) for the signal,thereby neglecting the effect of the interference between the additionalZ'-bosons and the Standard Model Z and {\gamma}. Recently, it has beenestablished that both finite width and interference effects can be dealt within experimental searches while still retaining the model independent approachensured by the NWA. This assessment has been made for the case of popularsingle Z'-boson models currently probed at the CERN Large Hadron Collider(LHC). In this paper, we test the scope of the CERN machine in relation to theabove issues for some benchmark multi Z'-boson models. In particular, weconsider Non-Universal Extra Dimensional (NUED) scenarios and the 4-DimensionalComposite Higgs Model (4DCHM), both predicting a multi-Z' peaking structure. Weconclude that in a variety of cases, specifically those in which the leptonicdecays modes of one or more of the heavy neutral gauge bosons are suppressedand/or significant interference effects exist between these or with thebackground, especially present when their decay widths are significant,traditional search approaches based on the assumption of rather narrow andisolated objects might require suitable modifications to extract the underlyingdynamics