Low-scale warped extra dimension and its predilection for multiple top quarks

TL;DR

This paper explores low-scale warped extra dimension models that predict multiple top quarks at the LHC, focusing on signatures like four-top events and their detection prospects with different lepton channels.

Contribution

It introduces a scenario with a lower Kaluza-Klein scale compatible with constraints, emphasizing four-top production as a key signature and analyzing detection strategies at the LHC.

Findings

Like-sign dilepton signature has high discovery potential at 2-2.5 TeV KK scale.

Single lepton channel is effective when left-handed top couples strongly.

Four top production via KK gluons is promising in a broad parameter space.

Abstract

Within warped extra dimension models that explain flavor through geometry, flavor changing neutral current constraints generally force the Kaluza-Klein scale to be above many TeV. This creates tension with a natural electroweak scale. On the other hand, a much lower scale compatible with precision electroweak and flavor changing neutral current constraints is allowed if we decouple the Kaluza-Klein states of Standard Model gauge bosons from light fermions $c_{\rm light}\simeq c_b\simeq 0.5$ bulk mass parameters). The main signature for this approach is four top quark production via the Kaluza-Klein excitations' strong coupling to top quarks. We study single lepton, like-sign dilepton, and trilepton observables of four-top events at the Large Hadron Collider. The like-sign dilepton signature typically has the largest discovery potential for a strongly coupled right-handed top case ($M_{KK} \sim 2-2.5 \TeV$), while single lepton is the better when the left-handed top couples most strongly ($M_{KK} \sim 2 \TeV$). We also describe challenging lepton-jet collimation issues in the like-sign dilepton and trilepton channels. An alternative single lepton observable is considered which takes advantage of the many bottom quarks in the final state. Although searches of other particles may compete, we find that four top production via Kaluza-Klein gluons is most promising in a large region of this parameter space.