Constraining scalar resonances with top-quark pair production at the LHC
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Springer
Received: November 10, Revised: February 7, Accepted: February 25, Published: March 6,
2017 2018 2018 2018
Diogo Buarque Franzosi,a Federica Fabbrib and Steffen Schumanna a
Institut f¨ ur Theoretische Physik, Universit¨ at G¨ ottingen, Friedrich-Hund-Platz 1, 37077 G¨ ottingen, Germany b Dipartimento di Fisica e Astronomia, Universit` a di Bologna and INFN, Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
E-mail: [email protected], [email protected], [email protected] 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, m(tt¯). We make use of stateof-the-art Monte Carlo event simulation to perform a direct comparison with measurements of m(tt¯) 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. Keywords: Beyond Standard Model, Perturbative QCD, Technicolor and Composite Models ArXiv ePrint: 1711.00102
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP03(2018)022
JHEP03(2018)022
Constraining scalar resonances with top-quark pair production at the LHC
Contents 1 Introduction
1
2 Simulation framework
2
3 Analysis framework
3 9 12
5 Results 5.1 Pseudo-scalar color octet 5.2 Pseudo-scalar singlet 5.3 Broad scalar color singlet
13 16 17 21
6 Conclusion
23
A Line-shapes samples
24
1
Introduction
With its mass being close to the electroweak scale the top quark is very special. It might intimately be connected to the underlying mechanism of electroweak symmetry breaking (EWSB). Consequently, studying top-quark production and decays at colliders might provide a portal to New Physics (NP). The Large Hadron Collider (LHC), providing protonproton collisions currently at 13 TeV centre-of-mass energy, can be seen as a top-quark factory. It allows to search for anomalous top-quark production and decay processes, considered as low energy modifications of the Standard Model (SM) parametrized by effective operators [1–6], or, as the direct production of intermediate resonances, which have been hunted for a long time at different experiments [7–9]. Heavy scalar resonances that decay into a pair of top quarks are predicted by several NP scenarios, in particular the Two Higgs Doublet Model (THDM), supersymmetric theories and models of dynamical EWSB. In this paper, we provide a framework to reinterpret the SM tt¯ differential cross section measurements as exclusion limits for signatures of NP resonances decaying into tt¯. The framework relies on the comparison between particle-level data with state-of-the-art event simulation and the interpretation of deviation
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