Discovery potential of top-partners in a realistic composite Higgs model with early LHC data

TL;DR

The study investigates a realistic composite Higgs model with two top-partner multiplets, predicting light quarks such as a charge-5/3 state that could be observed with early LHC data at $\sqrt{s}=7$ TeV$. It implements the model in MadGraph, simulates signal and SM backgrounds, and analyzes multi-lepton final states, identifying same-sign dileptons and opposite-sign trileptons as the most promising discovery channels with about 200 pb$^{-1}$. The authors propose a novel mass-reconstruction technique for the charge-5/3 quark using the tail of the same-sign dilepton invariant-mass distribution, and demonstrate that a few tens of pb$^{-1}$ could yield a 5$\sigma$ signal for representative benchmark points. The results indicate that early LHC data could not only discover light top-partners but also provide evidence for the presence of multiple top-partners by analyzing kinematic distributions and cross-section patterns. These findings have significant implications for testing the composite Higgs framework and for guiding early LHC searches in multi-lepton channels.

Abstract

Composite Higgs models provide a natural, non-supersymmetric solution to the hierarchy problem. In these models, one or more sets of heavy top-partners are typically introduced. Some of these new quarks can be relatively light, with a mass of a few hundred GeV, and could be observed with the early LHC collision data expected to be collected during 2010. We analyse in detail the collider signatures that these new quarks can produce. We show that final states with two (same-sign) or three leptons are the most promising discovery channels. They can yield a 5 sigma excess over the Standard Model expectation already with the 2010 LHC collision data. Exotic quarks of charge 5/3 are a distinctive feature of this model. We present a new method to reconstruct their masses from their leptonic decay without relying on jets in the final state.