Loopholes in Z′ searches at the LHC: exploring supersymmetric and leptophobic scenarios

Searching for heavy vector bosons Z', predicted in models inspired by Grand Unification Theories, is among the challenging objectives of the LHC. The ATLAS and CMS collaborations have looked for Z' bosons assuming that they can decay only into Standard Model channels, and have set exclusion limits by investigating dilepton, dijet and, to a smaller extent, top-antitop final states. In this work we explore possible loopholes in these Z' searches, by studying supersymmetric as well as leptophobic scenarios. We demonstrate the existence of realizations in which the Z' boson automatically evades the typical bounds derived from the analyses of the Drell-Yan invariant-mass spectrum. Dileptonic final states can in contrast only originate from supersymmetric Z' decays and are thus accompanied by additional effects. This feature is analyzed in the context of judiciously chosen benchmark configurations, for which visible signals could be expected in future LHC data with a 4 sigma-7 sigma significance. Our results should hence motivate an extension of the current Z' search program to account for supersymmetric and leptophobic models.