Abstract
The Drell-Yan di-lepton production at hadron colliders is by far the preferred channel to search for new heavy spin-1 particles. Traditionally, such searches have exploited the Narrow Width Approximation (NWA) for the signal, thereby neglecting the effect of the interference between the additional Z'-bosons and the Standard Model Z and {\gamma}. Recently, it has been established that both finite width and interference effects can be dealt with in experimental searches while still retaining the model independent approach ensured by the NWA. This assessment has been made for the case of popular single 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 the above issues for some benchmark multi Z'-boson models. In particular, we consider Non-Universal Extra Dimensional (NUED) scenarios and the 4-Dimensional Composite Higgs Model (4DCHM), both predicting a multi-Z' peaking structure. We conclude that in a variety of cases, specifically those in which the leptonic decays modes of one or more of the heavy neutral gauge bosons are suppressed and/or significant interference effects exist between these or with the background, especially present when their decay widths are significant, traditional search approaches based on the assumption of rather narrow and isolated objects might require suitable modifications to extract the underlying dynamics.
Highlights
The Drell-Yan di-lepton production at hadron colliders is by far the preferred channel to search for new heavy spin-1 particles
We have analysed the phenomenology of the Non-Universal ED and 4D Composite Higgs Models which are representative of two generic classes of multi-Z scenarios, weakly and strongly interacting respectively
We have examined the consequences of both FW and interference effects on the signal shape and rate and, eventually, on the interpretation of the data analysis results, as such effects are not generally included in the time-honoured Narrow Width Approximation (NWA) approach adopted by the experimental collaborations in searching for narrow spin-1 resonances
Summary
One of the flawed parts of the SM concerns the understanding of the gravitational interactions. In the class of NUED models in 5D, KK modes exist only for the gauge bosons, while fermions have no KK states, obviously, the particle content is very different from the ordinary SM inventory. In the more recent NUED(EW) construct, only the SU(2) × U(1) EW gauge bosons can propagate in the compactified ED and acquire KK excitations [26] In both models the fermionic content is totally confined on the 3D brane. The ensuing diagonalisation to determine the mass eigenvalues leads to a model dependent redefinition of gauge boson masses and couplings, which receive additional corrections from the KK states due to the rotation in state space The strength of these corrections depends on the contribution of the brane Higgs field, being proportional to powers of sin β. In particular, perform this analysis taking into account FW and interference effects as mentioned in the introduction
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