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

Collaboration
Jul 20, 2023
46 pages
Published in:
  • JHEP 10 (2023) 009
  • Published: Oct 3, 2023
e-Print:
Report number:
  • CERN-EP-2023-125
Experiments:

Citations per year

2022202320240112
Abstract: (Springer)
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 fb1^{−1} recorded at a centre-of-mass energy of s \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.[graphic not available: see fulltext]
Note:
  • 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