Dark Matter and how to find it: a search for low-mass leptophobic Dark Matter mediators and the development of mass-decorrelated jet taggers with the ATLAS experiment
dc.contributor.advisor
Leonidopoulos, Christos
en
dc.contributor.advisor
Clark, Philip
en
dc.contributor.author
Søgaard, Andreas
en
dc.contributor.sponsor
other
en
dc.date.accessioned
2019-09-25T10:58:52Z
dc.date.available
2019-09-25T10:58:52Z
dc.date.issued
2019-11-26
dc.description.abstract
A search for low-mass leptophobic Dark Matter (DM) mediator particles in 36 fb-1 of pp collision data at √s = 13 TeV collected by the ATLAS experiment is presented. The search is performed in final states where the mediator decay into a quark pair is reconstructed as a single, large-radius jet produced in association with a photon or a jet. No deviations from the Standard Model expectation are observed, and limits are placed on the production cross-section of leptophobic mediator particles and their coupling to quarks for mediator masses between 100 and 220 GeV. At the time of publication, this result constituted the lowest limits on leptophobic DM mediator masses for high-mass DM particles reported by ATLAS. Adversarial neural networks (ANN) are presented as a way to train jet taggers which decorrelates them from the invariant mass of the jet. An extensive study of five different approaches to constructing mass-decorrelated jet taggers is presented. The ANN tagger is found to provide the largest QCD multijet rejection at similar levels of mass-decorrelation.
en
dc.identifier.uri
http://hdl.handle.net/1842/36202
dc.language.iso
en
dc.publisher
The University of Edinburgh
en
dc.relation.hasversion
A. Søgaard, adversarial, https://github.com/asogaard/adversarial/tree/PUBNOTE, 2018
en
dc.relation.hasversion
ATLAS Collaboration, Search for light resonances decaying to boosted quark pairs and produced in association with a photon or a jet in proton–proton collisions at ps = 13 TeV with the ATLAS detector, Phys. Lett. B 788 (2019) 316, arXiv:1801.08769 [hep-ex].
en
dc.relation.hasversion
ATLAS Collaboration, Performance of mass-decorrelated jet substructure observables for hadronic two-body decay tagging in ATLAS, ATL-PHYS-PUB-2018-014, 2018, https://cds.cern.ch/record/2630973.
en
dc.subject
Standard Model
en
dc.subject
Dark Matter
en
dc.subject
mediator particle
en
dc.subject
high-energy proton–proton collisions
en
dc.subject
DM mediator particles
en
dc.subject
DM mediator decay
en
dc.subject
machine learning
en
dc.subject
jet identification observables
en
dc.title
Dark Matter and how to find it: a search for low-mass leptophobic Dark Matter mediators and the development of mass-decorrelated jet taggers with the ATLAS experiment
en
dc.type
Thesis or Dissertation
en
dc.type.qualificationlevel
Doctoral
en
dc.type.qualificationname
PhD Doctor of Philosophy
en
Files
Original bundle
1 - 1 of 1
- Name:
- Søgaard2019.pdf
- Size:
- 21.13 MB
- Format:
- Adobe Portable Document Format
This item appears in the following Collection(s)