Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Exploration of extended Higgs sectors, development of a displaced track trigger, and improvements in GRID middleware
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.ORCID iD: 0000-0003-1630-6664
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Two possible solutions to the Standard Model (SM) fine-tuning problem are presented in this thesis, MSSM and Compositeness. The Higgs sector of the MSSM can be tested by searching for charged Higgs bosons. Two direct searches for charged Higgs bosons decaying into a top- and bottom-quark are performed using 13.2 and 36.1 fb¹ respectively of pp collision data collected at √s = 13 TeV with the ATLAS detector. No significant excess over the SM background is observed and upper limits on σ(pp→tbH+B(H+→tb) between 0.07 and 2.9 pb are set at a 95% confidence level in the charged Higgs boson mass range 200–2000 GeV using the CLs method. The phenomenology of a vector-like top-partner decaying into a BSM (pseudo-) scalar is explored and interpreted in 2HDM and Compositeness models. The experimental reach is evaluated using γγ and Zγ final states, and the LHC is determined to be sensitive to top-partner and (pseudo-) scalar masses in the 1–2 TeV range both in the Run 2 and expected Run 3 datasets. Two hardware based hit collection methods targeting long-lived particles are studied for a regional track trigger in anticipation of the HL-LHC upgrade. The efficiency is estimated to be ~20% for a wide range of track parameters for tracks originating from a displaced vertex. The prospect of using GPU-computing on the LHC GRID is considered. Extensions of the ARC middleware Information Providers integrating local GPU information are demonstrated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. , p. 95
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1829
Keywords [en]
BSM, Supersymmetry, Standard Model, Higgs, 2HDM, Charged Higgs, Compositeness, Pattern Matching, GRID
National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
URN: urn:nbn:se:uu:diva-389896ISBN: 978-91-513-0700-8 (print)OAI: oai:DiVA.org:uu-389896DiVA, id: diva2:1339734
Public defence
2019-09-20, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2019-08-28 Created: 2019-07-31 Last updated: 2019-09-17
List of papers
1. Search for charged Higgs bosons in the H → tb decay channel in pp collisions at s = √13 TeV using the ATLAS detector.
Open this publication in new window or tab >>Search for charged Higgs bosons in the H → tb decay channel in pp collisions at s = √13 TeV using the ATLAS detector.
2016 (English)Conference paper, Published paper (Other academic)
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-329226 (URN)
Conference
38th International Conference on High Energy Physics (ICHEP) 2016
Available from: 2017-09-11 Created: 2017-09-11 Last updated: 2019-07-31
2. Search for charged Higgs bosons decaying into top and bottom quarks at √s=13TeV with the ATLAS detector
Open this publication in new window or tab >>Search for charged Higgs bosons decaying into top and bottom quarks at √s=13TeV with the ATLAS detector
Show others...
2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 11, article id 085Article in journal (Refereed) Published
Abstract [en]

A search for charged Higgs bosons heavier than the top quark and decaying via H-+/- tb is presented. The data analysed corresponds to 36.1 fb(-1) of pp collisions at TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, pp tbH(+/-), is explored in the mass range from m(H)+/- = 200 to 2000 GeV using multi-jet final states with one or two electrons or muons. Events are categorised according to the multiplicity of jets and how likely these are to have originated from hadronisation of a bottom quark. Multivariate techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching ratio of a charged Higgs boson as a function of its mass, which range from 2.9 pb at m(H)+/- = 200 GeV to 0.070 pb at m(H)+/- = 2000 GeV. The results are interpreted in two benchmark scenarios of the Minimal Supersymmetric Standard Model.

Keywords
Beyond Standard Model, Hadron-Hadron scattering (experiments), Higgs physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-372715 (URN)10.1007/JHEP11(2018)085 (DOI)000450508300001 ()
Funder
Swedish Research CouncilEU, European Research CouncilEU, Horizon 2020
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP11(2018)085

Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-07-31Bibliographically approved
3. Signatures of vector-like top partners decaying into new neutral scalar or pseudoscalar bosons
Open this publication in new window or tab >>Signatures of vector-like top partners decaying into new neutral scalar or pseudoscalar bosons
Show others...
2019 (English)In: Article in journal (Other academic) Epub ahead of print
Abstract [en]

We explore the phenomenology of models containing one Vector-Like Quark (VLQ), t′, which can decay into the Standard Model (SM) top quark, t, and a new spin-0 neutral boson, S, the latter being either a scalar or pseudoscalar state. We parametrise the underlying interactions in terms of a simplified model which enables us to capture possible Beyond the SM (BSM) scenarios. We discuss in particular three such scenarios: one where the SM state is supplemented by an additional scalar, one which builds upon a 2-Higgs Doublet Model (2HDM) framework and another which realises a Composite Higgs Model (CHM) through partial compositeness. Such exotic decays of the t′ can be competitive with decays into SM particles, leading to new possible discovery channels at the Large Hadron Collider (LHC). Assuming t′ pair production via strong interactions, we design signal regions optimised for one t′→St transition (while being inclusive on the other \bar{t'} decay, and vice versa), followed by the decay of S into the two very clean experimental signatures S→γγ and S→Z(→ℓ+ℓ−)γ. We perform a dedicated signal-to-background analysis in both channels, by using Monte Carlo (MC) event simulations modelling the dynamics from the proton-proton to the detector level. Under the assumption of BR(t′→St)=100%, we are therefore able to realistically quantify the sensitivity of the LHC to both the t′ and S masses, assuming both current and foreseen luminosities. This approach paves the way for the LHC experiments to surpass current VLQ search strategies based solely on t′ decays into SM bosons (W±,Z, h).

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-389895 (URN)
Available from: 2019-07-31 Created: 2019-07-31 Last updated: 2019-08-15Bibliographically approved
4. To catch a long-lived particle: hit selection towards a regional hardware track trigger implementation
Open this publication in new window or tab >>To catch a long-lived particle: hit selection towards a regional hardware track trigger implementation
Show others...
2019 (English)In: Article in journal (Refereed) Submitted
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-389892 (URN)
Available from: 2019-07-31 Created: 2019-07-31 Last updated: 2019-08-08
5. Extending the ARC Information Providers to report information on GPU resources
Open this publication in new window or tab >>Extending the ARC Information Providers to report information on GPU resources
2019 (English)In: Article in journal (Other academic) Epub ahead of print
National Category
Other Computer and Information Science Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-389893 (URN)
Available from: 2019-07-31 Created: 2019-07-31 Last updated: 2019-07-31

Open Access in DiVA

fulltext(2629 kB)48 downloads
File information
File name FULLTEXT01.pdfFile size 2629 kBChecksum SHA-512
5948c191c5e45f0cacdf64ad46dc3bed46806e35c291eca3ee4fc9f3d459e5db9825abe4ed3af81176ef2abd589dd4ca76063f17bfa8b6076b7c3675d1a78910
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Isacson, Max
By organisation
High Energy Physics
Subatomic Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 48 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 298 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf