Constraining scalar resonances with top-quark pair production at the LHC

Diogo Buarque Franzosi,Federica Fabbri,Steffen Schumann

doi:10.1007/jhep03(2018)022

Diogo Buarque Franzosi, Federica Fabbri + Show 1 more

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https://doi.org/10.1007/jhep03(2018)022

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Abstract

Constraints on models which predict resonant top-quark pair production at the LHC are provided via a reinterpretation of the Standard Model (SM) particle level measurement of the top-anti-top invariant mass distribution, mleft(toverline{t}right) . We make use of state-of-the-art Monte Carlo event simulation to perform a direct comparison with measurements of mleft(toverline{t}right) in the semi-leptonic channels, considering both the boosted and the resolved regime of the hadronic top decays. A simplified model to describe various scalar resonances decaying into top-quarks is considered, including CP-even and CP-odd, color-singlet and color-octet states, and the excluded regions in the respective parameter spaces are provided.

Highlights

In order to theoretically describe top-quark pair production at the LHC, we make use of state-of-the-art event simulations provided by the Sherpa [10] event-generator framework
The uncertainties are still quite large, since only the 2015 data, corresponding to 3.2 fb−1, were used, but we expect that an update of the analysis will be available in the near future, with improved systematics and statistical uncertainty allowing to derive real exclusion limits
In this work we have provided a framework to reinterpret the Standard Model (SM) ttdifferential cross section measurements in terms of exclusion limits for signatures of NP scalar resonances decaying into tt

Summary

Introduction

In order to theoretically describe top-quark pair production at the LHC, we make use of state-of-the-art event simulations provided by the Sherpa [10] event-generator framework. This implies the usage of techniques to match leading and next-to-leading order QCD matrix elements with parton showers and merging different partonmultiplicity final states. These approaches are complementary to model-specific searches in the respective final states. They provide systematic methods for the theory community to derive more realistic exclusion limits for any particular model, not relying on the experiment-specific assumptions

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