Scalar mass dependence of angular variables in \( t\overline{t}\phi \) production

Abstract

In this paper we explore CP discrimination in the associated production of top-quark pairs (\( t\overline{t} \)) with a generic scalar boson (𝜙) at the LHC. We probe the CP-sensitivity of several observables for a varying scalar boson mass and CP-number, either CP-even (𝜙 = H ) or CP-odd (𝜙 = A), using dileptonic final states of the \( t\overline{t}\phi \) system, with 𝜙 → \( b\overline{b} \). We show that CP-searches are virtually impossible for 𝜙 boson masses above a few hundred GeV in this channel. A full phenomenological analysis was performed, using Standard Model background and signal events generated with MadGraph5_aMC@NLO and reconstructed using a kinematic fit. The most sensitive CP-observables are used to compute Confidence Levels (CLs), as a function of luminosity, for the exclusion of different signal hypotheses with scalar and pseudoscalar boson masses that range from m𝜙 = 40 GeV up to 200 GeV. We finalize by analysing the impact of a measurement (or limit) of the CP-violating angle in the parameter space of a complex two-Higgs doublet model known as the C2HDM.

A preprint version of the article is available at ArXiv.

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Azevedo, D., Capucha, R., Onofre, A. et al. Scalar mass dependence of angular variables in \( t\overline{t}\phi \) production. J. High Energ. Phys. 2020, 155 (2020). https://doi.org/10.1007/JHEP06(2020)155

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Keywords

  • Beyond Standard Model
  • CP violation