LHC Signals for Warped Electroweak Neutral Gauge Bosons

Abstract: We study signals at the Large Hadron Collider (LHC) for Kaluza-Klein (KK) excitations of the electroweak gauge bosons in the framework with the Standard Model (SM) gauge and fermion fields propagating in a warped extra dimension. Such a framework addresses both the Planck-weak and flavor hierarchy problems of the SM. Unlike the often studied Z' cases, in this framework, there are three neutral gauge bosons due to the underlying SU(2)_L x SU(2)_R x U(1)_X gauge group in the bulk. Furthermore, couplings of these KK states to light quarks and leptons are suppressed, whereas those to top and bottom quarks are enhanced compared to the SM gauge couplings. Therefore, the production of light quark and lepton states is suppressed relative to other beyond the SM constructions, and the fermionic decays of these states are dominated by the top and bottom quarks, which are, though, overwhelmed by KK gluons dominantly decaying into them. However, as we emphasize in this paper, decays of these states to longitudinal W, Z and Higgs are also enhanced similarly to the case of top and bottom quarks. We show that the W, Z and Higgs final states can give significant sensitivity at the LHC to 2 (3) TeV KK scale with an integrated luminosity of 100 invfb (1 invab). Since current theoretical framework(s) favor KK masses greater than about 3 TeV, luminosity upgrade of LHC is likely to be crucial in observing these states.

Overview of "LHC Signals for Warped Electroweak Neutral Gauge Bosons"

This paper explores the phenomenology of Kaluza-Klein (KK) excitations of electroweak gauge bosons within a framework where Standard Model (SM) fields propagate in a warped extra dimension. This approach addresses the hierarchy problems in the SM, particularly the disparities between Planck-weak and flavor scales. Unlike traditional studies focusing on singular $Z^{\prime}$ scenarios, this model predicts three neutral gauge bosons stemming from the bulk $SU(2)_L \times SU(2)_R \times U(1)_X$ gauge group. The unique structure of this model suppresses KK state interactions with light quarks and leptons while enhancing interactions with top and bottom quarks. These interactions significantly influence the decay patterns, steering towards longitudinal $W$, $Z$, and Higgs channels, with potential detection sensitivity at the LHC.

Model Framework and Collider Signatures

The paper centralizes the concept of warped extra dimensions ala Randall-Sundrum (RS1) models, where SM fields operate within the bulk. This approach not only mitigates hierarchy issues but also constructs a natural mechanism for flavor hierarchies through field localization. The neutral gauge boson KK states differ structurally from common $Z^{\prime}$ setups, as their decay processes are dominated by top and bottom quarks. Moreover, the light quark and lepton channels are inherently suppressed, posing challenges yet yielding distinct collider signatures.

Particularly notable are KK gluons, whose decay into top quarks provides a robust collider signal, exploring production via longitudinal $W$ or $Z$ fusion. These enhanced decay channels lay out significant detection potential at mass scales of around 3 TeV, contingent on an upgraded LHC luminosity.

Numerical Results and Theoretical Implications

The authors rigorously calculate various decay widths and branching fractions for these KK modes. Key observations include sensitivity to KK scales approaching 2-3 TeV with integrated luminosities stretching from 100 fb$^{-1}$ to 1 ab$^{-1}$. These findings stimulate discussions on prospective theoretical models and collider designs crucial for confirming such predictions.

The paper maintains a formal stance, emphasizing how current theoretical models favor heavier KK masses close to or exceeding 3 TeV, suggesting that augmenting the luminosity of LHC is pivotal for observing these unique states.

Future Perspectives in AI and Beyond

The findings presented unearth pathways for future theoretical explorations and experimental implementations. As AI evolves, the data analysis and computational aspects within collider physics can further enhance the understanding and detection capabilities for these KK states. The paper posits a future where AI-driven algorithms improve signal extraction and event reconstruction amidst vast datasets, propelling theoretical investigations and experimental confirmations alike.

In sum, this paper presents a detailed exploration of the interactions and detectability of warped electroweak KK modes at the LHC. It delineates theoretical constraints and experimental avenues, offering insights that may steer both collider physics and AI applications in future scientific research.