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Journal of High Energy Physics

, 2019:157 | Cite as

The emergence of multi-lepton anomalies at the LHC and their compatibility with new physics at the EW scale

  • Stefan von BuddenbrockEmail author
  • Alan S. Cornell
  • Yaquan Fang
  • Abdualazem Fadol Mohammed
  • Mukesh Kumar
  • Bruce Mellado
  • Kehinde G. Tomiwa
Open Access
Regular Article - Experimental Physics
  • 44 Downloads

Abstract

A recent study [1] has shown that a simplified model predicting a heavy scalar of mass 270 GeV (H ) that decays to a Standard Model (SM) Higgs boson in association with a scalar singlet of mass 150 GeV (S) can accommodate several anomalous multi-lepton results in proton-proton collisions at the Large Hadron Collider (LHC). With this in mind, the goal of this article is to provide a more formal study of a wider set of LHC results pertaining to the production of multiple leptons. We find that a combination of such results lead to strong discrepancies between the data and SM Monte Carlo predictions. These discrepancies appear in corners of the phase-space where different SM processes dominate, indicating that the potential mismodeling of a single SM process is unlikely to explain them. Systematic uncertainties from the prediction of SM processes evaluated with currently available tools seem unable to explain away these discrepancies. A combination is able to constrain the simplified model’s single degree of freedom β2, related to the size of the Yukawa coupling of H to the top quark, to a value of 2.92 ± 0.35. This is in contrast to the absence of signal, where βg = 0. This result is discussed in the independent contexts of both potential for new physics in the existing LHC data as well as the limitations of our current understanding of the SM. That being said, QCD NNLO and EW NLO corrections in di-lepton final states are not expected to change the conclusions of this study. New results pertaining to the production of two opposite sign different flavour charged leptons with a full jet veto further confirm the presence of anomalies in similar corners of the leptonic phase-space.

Keywords

Hadron-Hadron scattering (experiments) 

Notes

Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited

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Copyright information

© The Author(s) 2019

Authors and Affiliations

  1. 1.School of Physics and Institute for Collider Particle PhysicsUniversity of the WitwatersrandJohannesburgSouth Africa
  2. 2.Institute of High Energy PhysicsBeijingChina
  3. 3.University of Chinese Academy of SciencesBeijingChina
  4. 4.iThemba LABSNational Research FoundationSomerset WestSouth Africa

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