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Optimization of event selection and fake background estimation in a search for heavy scalars in dilepton final states with the ATLAS detector

Burman Ingeberg, Marius LU (2021) FYSM60 20202
Particle Physics
Department of Physics
Abstract
The discovery of the Higgs boson h in 2012 further confirmed the remarkable accuracy of the Standard Model (SM). Despite this, some compelling excesses in multi-lepton final states were recorded in both major runs of the Large Hadron Collider (LHC). The excesses can be explained by the introduction of a model where a heavy boson X decays into a SM Higgs boson h and a singlet scalar S with Higgs-like couplings. The h and S subsequently produce opposite-sign different flavor lepton final states. Due to the plethora of SM processes producing similar final states, an accurate selection of events produced in the LHC is essential. This thesis investigates the optimization of the event selection using the full LHC Run 2 data recorded using the... (More)
The discovery of the Higgs boson h in 2012 further confirmed the remarkable accuracy of the Standard Model (SM). Despite this, some compelling excesses in multi-lepton final states were recorded in both major runs of the Large Hadron Collider (LHC). The excesses can be explained by the introduction of a model where a heavy boson X decays into a SM Higgs boson h and a singlet scalar S with Higgs-like couplings. The h and S subsequently produce opposite-sign different flavor lepton final states. Due to the plethora of SM processes producing similar final states, an accurate selection of events produced in the LHC is essential. This thesis investigates the optimization of the event selection using the full LHC Run 2 data recorded using the ATLAS detector at a centre-of-mass energy of 13 TeV, with the corresponding luminosity of 139 fb−1. An investigation of the lepton isolation is conducted, where the highest performing working point is selected. In order to further suppress background, an event selection is constructed using a multidimensional signal significance scan. Finally, the background due to misidentified leptons is estimated using a data-driven method. (Less)
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author
Burman Ingeberg, Marius LU
supervisor
organization
course
FYSM60 20202
year
type
H1 - Master's Degree (One Year)
subject
keywords
Physics, Particle physics, ATLAS, Standard Model, CERN, LHC, Higgs boson, Exotic Higgs Boson, Dilepton final states, Optimization
language
English
id
9036845
date added to LUP
2021-01-22 10:17:46
date last changed
2021-01-22 10:17:46
@misc{9036845,
  abstract     = {{The discovery of the Higgs boson h in 2012 further confirmed the remarkable accuracy of the Standard Model (SM). Despite this, some compelling excesses in multi-lepton final states were recorded in both major runs of the Large Hadron Collider (LHC). The excesses can be explained by the introduction of a model where a heavy boson X decays into a SM Higgs boson h and a singlet scalar S with Higgs-like couplings. The h and S subsequently produce opposite-sign different flavor lepton final states. Due to the plethora of SM processes producing similar final states, an accurate selection of events produced in the LHC is essential. This thesis investigates the optimization of the event selection using the full LHC Run 2 data recorded using the ATLAS detector at a centre-of-mass energy of 13 TeV, with the corresponding luminosity of 139 fb−1. An investigation of the lepton isolation is conducted, where the highest performing working point is selected. In order to further suppress background, an event selection is constructed using a multidimensional signal significance scan. Finally, the background due to misidentified leptons is estimated using a data-driven method.}},
  author       = {{Burman Ingeberg, Marius}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Optimization of event selection and fake background estimation in a search for heavy scalars in dilepton final states with the ATLAS detector}},
  year         = {{2021}},
}