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Balazs Konya

Researcher

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Search for top-quark decays t → Hq with 36 fb−1 of pp collision data at √s = 13 TeV with the ATLAS detector

Author

  • M Aaboud
  • Torsten Åkesson
  • Simona Bocchetta
  • Lene Bryngemark
  • Eric Corrigan
  • Caterina Doglioni
  • Kristian Gregersen
  • Eva Brottmann Hansen
  • Vincent Hedberg
  • Göran Jarlskog
  • Charles Kalderon
  • Edgar Kellermann
  • Balazs Konya
  • Else Lytken
  • Katja Mankinen
  • Caterina Marcon
  • Ulf Mjörnmark
  • Geoffrey Mullier
  • Ruth Pöttgen
  • Trine Poulsen
  • Oxana Smirnova
  • L Zwalinski
Show all

Summary, in English

A search for flavour-changing neutral current decays of a top quark into an up-type quark (q = u, c) and the Standard Model Higgs boson, t → Hq, is presented. The search is based on a dataset of pp collisions at s = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 36.1 fb−1. Two complementary analyses are performed to search for top-quark pair events in which one top quark decays into Wb and the other top quark decays into Hq, and target the H→ bb¯ and H → τ+τ− decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying τ-leptons, is exploited in the two analyses respectively. Multivariate techniques are used to separate the signal from the background, which is dominated by top-quark pair production. No significant excess of events above the background expectation is found, and 95% CL upper limits on the t → Hq branching ratios are derived. The combination of these searches with ATLAS searches in diphoton and multilepton final states yields observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 1.1 × 10−3 (8.3 × 10−4) and 1.2 × 10−3 (8.3 × 10−4), respectively. The corresponding combined observed (expected) upper limits on the |λtcH| and |λtuH| couplings are 0.064 (0.055) and 0.066 (0.055), respectively.[Figure not available: see fulltext.] © 2019, The Author(s).

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration

Publishing year

2019

Language

English

Publication/Series

Journal of High Energy Physics

Volume

2019

Issue

5

Document type

Journal article

Publisher

Springer

Topic

  • Subatomic Physics

Keywords

  • Hadron-Hadron scattering (experiments)
  • Rare decay
  • Top physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 1029-8479