Search for exotic Higgs boson decays to four leptons with the ATLAS detector

Searches for exotic Higgs boson decays are well motivated by various theoretical models, as well as the constraints from Higgs boson measurement results. The focus is on exotic Higgs boson decays to a pair of beyond-the-Standard-Model spin-0 particles $a$. This dissertation conducts two analyses for exotic Higgs bosons decaying into leptons, which are H\rightarrow2a\rightarrow4μ and $H\rightarrow2a\rightarrow4\tau$, and target the mass ranges of 1<m_a<15\text{ GeV} and 15<m_a<60\text{ GeV}. Various data-driven techniques are developed and used to estimate the background that cannot be well modeled with the standard simulation in ATLAS. The searches use proton-proton collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 139\text{ fb}^-1 and a center of mass energy $\sqrt{s}=13\text{ TeV}$. No significant excess has been observed. Therefore, this dissertation summarizes the $95\%$ confidence-level upper limits of the branching ratio of exotic Higgs decays to a pair of beyond-the-Standard-Model light scalars in the lepton final states

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2020

Author dc:creator

• Cai, Huacheng

Contributors dc:contributor

• Martinez Outschoorn, Verena Ingrid
• Pitts, Kevin
• Peng, Jen-Chieh
• Shelton, Jessie
• Coelho Lopes de Sa, Rafael

• high energy physics experiments
• Higgs physics
• beyond Standard Model physics
• LHC physics
• ATLAS detector

Statement dc:rights

• Copyright 2020 Huacheng Cai

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/107860

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/107860