Abstract
We propose a new search strategy for heavy top partners at the early stages of the LHC run-II, based on lepton-jet final states. Our results show that final states containing a boosted massive jet and a hard lepton, in addition to a top quark and possibly a forward jet, offer a new window to both detecting and measuring top partners of mass ∼ 2TeV. Our resulting signal significance is comparable or superior to the same sign dilepton channels for top partner masses heavier than roughly 1 TeV. Unlike the di-lepton channel, the selection criteria we propose are sensitive both to 5/3 and 1/3 charge top partners and allow for full reconstruction of the resonance mass peak. Our search strategy utilizes a simplified b-tagging procedure and the Template Overlap Method to tag the massive boosted objects and reject the corresponding backgrounds. In addition, we propose a new, pileup insensitive method, to tag forward jets which characterize our signal events. We consider full effects of pileup contamination at 50 interactions per bunch crossing. We demonstrate that even in the most pessimistic pileup scenarios, the significance we obtain is sufficient to claim a discovery over a wide range of top partner parameters. While we focus on the minimal natural composite Higgs model, the results of this paper can be easily translated into bounds on any heavy partner with a $$ t\overline{t}Wj $$ final state topology.
Highlights
Though the SM cannot explain several experimental observations such as the neutrino masses, the baryon asymmetry of the universe and the origin of dark matter one cannot deduce with any certainty the energy scale at which the extensions of the SM would be relevant, with the exceptions of the Planck scale and the scale of the Landau pole of the hyper charge interactions
While we focus on the minimal natural composite Higgs model, the results of this paper can be translated into bounds on any heavy partner with a ttW j final state topology
We propose a novel approach to forward jet tagging, which addresses the effects of pileup contamination
Summary
We use the Minimal Composite Higgs Model (MCHM) [19] as a benchmark for illustrating the performance of our event selection searches for top partners. We give a brief overview of the model features important for our phenomenological study. The low energy description of the strongly coupled sector with “weakly coupled” deformations is expected to contain additional scalar, fermionic and vector resonances, typically at a scale g∗f , where f is the scale of compositeness and g∗ is a strong coupling, O(1) ≤ g∗ ≤ 4π. A generic feature of composite Higgs models is that the 5/3 charge partner (X5/3) is the lightest state amongst the partners in the 4. Where cR is a right-handed strong sector coupling between the partners in the 1 and 4.4
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