LHC Signals from Warped Extra Dimensions

TL;DR

This paper investigates the detection prospects of Kaluza-Klein gluons in warped extra dimension models at the LHC, highlighting challenges due to suppressed production and broad decay widths, but also identifying potential signals for masses up to 4 TeV.

Contribution

It demonstrates that KK gluons with masses below 4 TeV can be discovered at the LHC using polarization asymmetries and energetic top-jets, despite suppressed couplings and broad decay widths.

Findings

KK gluons with mass a0a0 4 TeV are detectable at 100 fb^{-1}

Polarization asymmetry enhances signal significance

Highly energetic top-jets are key signatures

Abstract

We study production of Kaluza-Klein gluons (KKG) at the Large Hadron Collider (LHC) in the framework of a warped extra dimension with the Standard Model (SM) fields propagating in the bulk. We show that the detection of KK gluon is challenging since its production is suppressed by small couplings to the proton's constituents. Moreover, the KK gluon decays mostly to top pairs due to an enhanced coupling and hence is broad. Nevertheless, we demonstrate that for m_{KKG} \lesssim 4 TeV, 100 fb^{-1} of data at the LHC can provide discovery of the KK gluon. We utilize a sizeable left-right polarization asymmetry from the KK gluon resonance to maximize the signal significance, and we explore the novel feature of extremely highly energetic "top-jets". We briefly discuss how the detection of electroweak gauge KK states (Z/W) faces a similar challenge since their leptonic decays (``golden'' modes) are suppressed. Our analysis suggests that other frameworks, for example little Higgs, which rely on UV completion via strong dynamics might face similar challenges, namely (1) Suppressed production rates for the new particles (such as Z'), due to their ``light-fermion-phobic'' nature, and (2) Difficulties in detection since the new particles are broad and decay predominantly to third generation quarks and longitudinal gauge bosons.