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Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector

ContributorsATLAS Collaboration
Published inThe journal of high energy physics, vol. 2023, no. 10, 9
Publication date2023
First online date2023-10-03
Abstract

A search for a new heavy scalar particle X decaying into a Standard Model (SM) Higgs boson and a new singlet scalar particle S is presented. The search uses a proton-proton (pp) collision data sample with an integrated luminosity of 140 fb$^{−1}$ recorded at a centre-of-mass energy of $ \sqrt{s} $ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The most sensitive mass parameter space is explored in X mass ranging from 500 to 1500 GeV, with the corresponding S mass in the range 200–500 GeV. The search selects events with two hadronically decaying τ-lepton candidates from H → τ$^{+}$τ$^{−}$ decays and one or two light leptons (ℓ = e, μ) from S → VV (V = W, Z) decays while the remaining V boson decays hadronically or to neutrinos. A multivariate discriminant based on event kinematics is used to separate the signal from the background. No excess is observed beyond the expected SM background and 95% confidence level upper limits between 72 fb and 542 fb are derived on the cross-section σ(pp → X → SH) assuming the same SM-Higgs boson-like decay branching ratios for the S → VV decay. Upper limits on the visible cross-sections σ(pp → X → SH → WWττ) and σ(pp → X → SH → ZZττ) are also set in the ranges 3–26 fb and 6–33 fb, respectively.

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Keywords
  • Hadron-Hadron Scattering
  • p p: scattering
  • p p: colliding beams
  • scalar particle: heavy
  • scalar particle: singlet
  • scalar particle: decay modes
  • vector boson: pair production
  • vector boson: decay modes
  • scalar particle: mass
  • singlet: scalar
  • new particle
  • background
  • ATLAS
  • Higgs particle: leptonic decay
  • tau: pair production
  • tau: hadronic decay
  • electron
  • muon
  • scalar particle: branching ratio
  • CERN LHC Coll
  • kinematics
  • channel cross section: upper limit
  • data analysis method
  • experimental results
  • 13000 GeV-cms
Citation (ISO format)
ATLAS Collaboration. Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector. In: The journal of high energy physics, 2023, vol. 2023, n° 10, p. 9. doi: 10.1007/jhep10(2023)009
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ISSN of the journal1029-8479
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