Indirect Searches for $Z'$-like Resonances at the LHC

TL;DR

This paper investigates the potential for detecting $Z'$-like particles indirectly at the LHC through Drell-Yan processes, concluding it's generally unlikely except in special extra-dimensional models with KK excitations.

Contribution

It provides a comprehensive analysis of indirect detection prospects for $Z'$-like resonances, highlighting the unique case of KK excitations where interference effects enhance sensitivity.

Findings

Indirect detection is unlikely for most models due to statistical limitations.

Degenerate KK excitations of photon and Z can be detected indirectly due to interference effects.

Standard Model background suppresses the signals except in special extra-dimensional scenarios.

Abstract

We explore the possibility of indirectly observing the effects of $Z'$-like particles with electroweak strength couplings in the Drell-Yan channel at the LHC with masses above the resonance direct search reach. We find that, mostly due to statistical limitations, this is very unlikely in almost all classes of models independently of the spin of the resonance. Not unexpectedly, the one possible exception to this general result is the case of degenerate Kaluza-Klein (KK) excitations of the photon and $Z$ that occur in some extra-dimensional models. In this special case, the strong destructive interference with the Standard Model (SM) exchanges below the resonance mass leads to a well-known significant suppression of the cross section and thus increased sensitivity to this particular new physics scenario.