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Search for periodic resonances at √s = 13 TeV with ATLAS detector
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- Author / Creator
- Lau, Ho Chun
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Integrating gravity into the Standard Model (SM) of particle physics presents a chal- lenge in formulating a unified theory of all interactions. Quantum gravity inherits a principle from quantum field theories. Here, gravity is interpreted as a field. This conceptualization leads to the quantization of the gravitional field, which necessitates the hypothesis of a tensor spin-2 particle, known as the graviton (G), as the gravi- tational force carrier. Previous models such as the Arkani-Dimopoulos-Dvali (ADD) large extra dimensions model and the Randall-Sundrum (RS) wrapped extra dimen- sion model attempted to unify gravity with other forces and predict the existence of gravitons. However, the absence of experimental evidence to support the predictions of these models has halted their success. The clockwork/linear dilaton (CW/LD) model which is a variation of two models offers an alternative approach. It predicts a series of massive gravitons that may be produced at Large Hadron Collider colli- sion energies, and appear in the detectors through 2-body graviton decays, such as G → e+e− and G → γγ. The graviton resonance pattern is different from predictions of the ADD and RS models.
This thesis presents an analysis of the e+e− and γγ invariant mass spectrums acquired by the ATLAS experiment during 2015 to 2018 with an integrated luminosity of 140 fb−1 at √s = 13 TeV. A Fourier transform tailored to the CW/LD model’s periodic signal hypothesis, is used to search for graviton resonances. An invariant mass range of [250, 4182] GeV for e+e−, and [150, 2360] GeV for γγ has been searched. The investigation reveals no significant deviations from SM expectations. The most pronounced signal appears with a period of 1 TeV(0.6 TeV) in the e+e−(γγ) invariant
mass spectrum with a global significance of 0.14(0.20) standard deviations. In the absence of a significant excess, we constrain the parameter space of the CW/LD model by setting exclusion limits. -
- Graduation date
- Spring 2024
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.