Ruby, Adam
(2023)
Searches for Axion-Like Particles in Rare Higgs Boson Decays with the ATLAS Detector.
PhD thesis, University of Liverpool.
|
Text
200940164_Feb2023.pdf - Author Accepted Manuscript Download (22MB) | Preview |
Abstract
This thesis presents a search for the decay of the Higgs boson to a Z boson and a light, pseudoscalar axion-like particle, where the Z boson decays to a pair of electrons or muons and the a particle decays to a pair of photons. The search is performed using 139 fb⁻¹ proton-proton LHC collision data at √s = 13 TeV collected by the ATLAS detector between 2015 and 2018. The mass of the ALP is assumed to be between 0.1 GeV and 10 GeV and the data are analysed in two selection categories; the merged category and the resolved category. Events are selected to the merged category if both photons from the ALP decay are reconstructed in the ATLAS calorimeter as a single cluster whereas resolved category events are such that they are separately reconstructed. The main background processes in this search are Z boson productions in association with photons or particle jets that are reconstructed as photons. No excess is observed for the ALP mass range chosen in this analysis. The data is in agreement with Standard Model predictions with upper limits on the branching ratio BR(h → Za) × BR(a → γγ) at 95 % confidence level found to vary from 0.1 % to 4 % depending on the mass value of the ALP.
| Item Type: | Thesis (PhD) |
|---|---|
| Divisions: | Faculty of Science and Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 24 Aug 2023 14:36 |
| Last Modified: | 01 Oct 2023 01:30 |
| DOI: | 10.17638/03171241 |
| Supervisors: |
|
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3171241 |
Dimensions
Dimensions
