Searching For Supersymmetry With The Atlas Detector At The Large Hadron Collider
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Electroweak Physics At The Large Hadron Collider With The Atlas Detector
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Author : Elodie Resseguie
language : en
Publisher: Springer Nature
Release Date : 2020-11-03
Electroweak Physics At The Large Hadron Collider With The Atlas Detector written by Elodie Resseguie and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-11-03 with Science categories.
This thesis discusses searches for electroweakly produced supersymmetric partners of the gauge and the Higgs bosons (gauginos and higgsinos) decaying to multiple leptons, using pp collisions at sqrt(s) = 13 TeV. The thesis presents an in-depth study of multiple searches, as well as the first 13 TeV cross section measurement for the dominant background in these searches, WZ production. Two searches were performed using 36.1/fb of data: the gaugino search, which makes use of a novel kinematic variable, and the higgsino search, which produced the first higgsino limits at the LHC. A search using 139/fb of data makes use of a new technique developed in this thesis to cross check an excess of data above the background expectation in a search using a Recursive Jigsaw Reconstruction technique. None of the searches showed a significant excess of data, and limits were expanded with respect to previous results. These searches will benefit from the addition of luminosity during HL-LHC; however, the current detector will not be able to withstand the increase in radiation. Electronics for the detector upgrade are tested and irradiated to ensure their performance.
Searching For Supersymmetry With The Atlas Detector At The Large Hadron Collider
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Author : Sky Trillium French
language : en
Publisher:
Release Date : 2011
Searching For Supersymmetry With The Atlas Detector At The Large Hadron Collider written by Sky Trillium French and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Third Generation Susy And T T Z Production
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Author : Josh McFayden
language : en
Publisher: Springer
Release Date : 2014-06-06
Third Generation Susy And T T Z Production written by Josh McFayden and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-06-06 with Science categories.
This thesis describes searches for new particles predicted by the super symmetry (SUSY) theory, a theory extending beyond the current Standard Model of particle physics, using the ATLAS detector at the CERN Large Hadron Collider. The thesis focuses on searches for stop and sbottom squarks, the SUSY partners of the top and bottom quarks, which are expected to be lighter than the partners of the first and second generation quarks and therefore good candidates for the first evidence of SUSY. It describes novel techniques for estimating and rejecting the Standard-Model backgrounds to searches for these particles. It also includes an independent analysis seeking to constrain the Standard Model ttZ background process, which also represents the first ATLAS search for this rare process at the LHC. The stop squark analysis described, with substantial leading contributions from the author, is the first search for these particles at the LHC to use the jets plus missing transverse energy plus 0-lepton signature and provides the world's best limits on the stop mass for light neutralino LSPs. All in all, the thesis describes three different world-leading analyses in both Standard Model and SUSY physics and therefore represents a major contribution to the field.
The Search For Supersymmetry In Hadronic Final States Using Boosted Object Reconstruction
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Author : Giordon Stark
language : en
Publisher: Springer Nature
Release Date : 2020-03-13
The Search For Supersymmetry In Hadronic Final States Using Boosted Object Reconstruction written by Giordon Stark and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-03-13 with Science categories.
This thesis represents one of the most comprehensive and in-depth studies of the use of Lorentz-boosted hadronic final state systems in the search for signals of Supersymmetry conducted to date at the Large Hadron Collider. A thorough assessment is performed of the observables that provide enhanced sensitivity to new physics signals otherwise hidden under an enormous background of top quark pairs produced by Standard Model processes. This is complemented by an ingenious analysis optimization procedure that allowed for extending the reach of this analysis by hundreds of GeV in mass of these hypothetical new particles. Lastly, the combination of both deep, thoughtful physics analysis with the development of high-speed electronics for identifying and selecting these same objects is not only unique, but also revolutionary. The Global Feature Extraction system that the author played a critical role in bringing to fruition represents the first dedicated hardware device for selecting these Lorentz-boosted hadronic systems in real-time using state-of-the-art processing chips and embedded systems.
Search For Supersymmetry Using Heavy Flavour Jets With The Atlas Detector At The Large Hadron Collider
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Author : Alan Tua
language : en
Publisher:
Release Date : 2013
Search For Supersymmetry Using Heavy Flavour Jets With The Atlas Detector At The Large Hadron Collider written by Alan Tua and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
The Standard Model of particle physics, despite being extremely successful, is not the ultimate description of physics. The nature of dark matter is not well described, unification of the forces is not achieved and the theory is plagued by a hierarchy problem. One of the proposed solutions to these issues is supersymmetry. This thesis describes numerous searches for supersymmetry carried out using the ATLAS detector at the Large Hadron Collider. In scenarios where R-parity is conserved, supersymmetric final states contain large amounts of missing transverse energy. Furthermore, should supersymmetry correctly describe Nature, the scalar partners of the third generation quarks might be the lightest scalar quarks. The searches reported here exploit these possibilities and make use of signatures which are rich in missing transverse energy and jets coming from heavy flavour quarks. Searches are carried out for direct pair production of third generation scalar quarks as well as gluino-mediated production of these particles. A data driven technique to estimate the backgrounds coming from multijet production is described and shown to work in analyses targeting heavy flavour quarks. No significant excesses are observed in a number of analyses. In each case limits are set on the allowed masses of supersymmetric particles in a variety of phenomenological models and in specific supersymmetry breaking scenarios.
Searching For Squarks
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Author : Samuel Jones
language : en
Publisher: Springer Nature
Release Date : 2020-08-27
Searching For Squarks written by Samuel Jones and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-08-27 with Science categories.
This thesis focuses on searches for squarks with the ATLAS detector in "compressed" scenarios where the scalar top is very close in mass to the lightest supersymmetric particle. These models are theoretically appealing because the presence of a quasi-degenerate scalar top enhances the self-annihilation cross-section of the lightest supersymmetric particle, acting therefore as a regulator of the dark matter relic density. Two main analyses are presented: the first is a search for scalar tops decaying to charm quarks. The identification of jets originating from the charm quark is very challenging due to its short lifetime. The calibration of tools for charm-tagging has paved the way to measuring the decay of the Higgs boson to pairs of charm quarks. The second analysis presented is the development of a novel technique for reconstructing low momentum b-hadrons. This tool has enabled the ATLAS collaboration to explore topologies that were previously inaccessible.
Search For Supersymmetry Using A Higgs Boson In The Decay Cascade With The Atlas Detector At The Large Hadron Collider
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Author : Claire David
language : en
Publisher:
Release Date : 2016
Search For Supersymmetry Using A Higgs Boson In The Decay Cascade With The Atlas Detector At The Large Hadron Collider written by Claire David and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
The Standard Model of particle physics is a successful theory, yet it is incomplete. Supersymmetry is one of the favoured extensions of the Standard Model, elegantly addressing several unresolved issues. This thesis presents a search for the pair production of supersymmetric particles chargino one and neutralino two, where the neutralino two decays to the lightest neutralino and the 125 GeV Higgs boson. The final states considered for the search have large missing transverse momentum, an isolated lepton and two jets identified as originating from bottom quarks. The analysis is based on 20.3 inverse femtobarns of 8 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. No excess over Standard Model predictions is observed. The analysis has been combined with three independent searches that probe other decay modes of the Standard Model Higgs boson. Limits are set at 95% confidence level in the context of a simplified supersymmetric model. Common masses of chargino one and neutralino two are excluded up to 250 GeV for a massless neutralino one. The analysis of this dissertation has been reinterpreted in the context of a large scan of the phenomenological Minimal Supersymmetric Standard Model, along with 22 other ATLAS Run 1 searches. The resulting summary paper represents the most comprehensive assessment of the ATLAS constraints on Supersymmetry models to date.
Search For Dark Matter With The Atlas Detector
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Author : Johanna Gramling
language : en
Publisher: Springer
Release Date : 2018-08-01
Search For Dark Matter With The Atlas Detector written by Johanna Gramling and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-08-01 with Science categories.
This book discusses searches for Dark Matter at the CERN’s LHC, the world’s most powerful accelerator. It introduces the relevant theoretical framework and includes an in-depth discussion of the Effective Field Theory approach to Dark Matter production and its validity, as well as an overview of the formalism of Simplified Dark Matter models. Despite overwhelming astrophysical evidence for Dark Matter and numerous experimental efforts to detect it, the nature of Dark Matter still remains a mystery and has become one of the hottest research topics in fundamental physics. Two searches for Dark Matter are presented, performed on data collected with the ATLAS experiment. They analyze missing-energy final states with a jet or with top quarks. The analyses are explained in detail, and the outcomes and their interpretations are discussed, also in view of the precedent analysis of theoretical approaches. Given its depth of coverage, the book represents an excellent reference guide for all physicists interested in understanding the theoretical and experimental considerations relevant to Dark Matter searches at the LHC.
A Search For Displaced Leptons In The Atlas Detector
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Author : Lesya Horyn
language : en
Publisher: Springer Nature
Release Date : 2022-02-07
A Search For Displaced Leptons In The Atlas Detector written by Lesya Horyn and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-02-07 with Science categories.
This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters. This signature provides unique sensitivity to the production of theoretical lepton-partners, sleptons. These particles are a feature of supersymmetric theories, which seek to address unanswered questions in nature. The signature searched for in this thesis is difficult to identify, and in fact, this is the first time it has been probed at the Large Hadron Collider (LHC). It covers a long-standing gap in coverage of possible new physics signatures. This thesis describes the special reconstruction and identification algorithms used to select leptons with large impact parameters and the details of the background estimation. The results are consistent with background, so limits on slepton masses and lifetimes in this model are calculated at 95% CL, drastically improving on the previous best limits from the Large Electron Positron Collider (LEP).
Searches For Supersymmetric Particles In Final States With Multiple Top And Bottom Quarks With The Atlas Detector
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Author : Chiara Rizzi
language : en
Publisher: Springer Nature
Release Date : 2020-09-01
Searches For Supersymmetric Particles In Final States With Multiple Top And Bottom Quarks With The Atlas Detector written by Chiara Rizzi and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-09-01 with Science categories.
This PhD thesis documents two of the highest-profile searches for supersymmetry performed at the ATLAS experiment using up to 80/fb of proton-proton collision data at a center-of-mass energy of 13 TeV delivered by the Large Hadron Collider (LHC) during its Run 2 (2015-2018). The signals of interest feature a high multiplicity of jets originating from the hadronisation of b-quarks and large missing transverse momentum, which constitutes one of the most promising final state signatures for discovery of new phenomena at the LHC. The first search is focused on the strong production of a pair of gluinos, with each gluino decaying into a neutralino and a top-antitop-quark pair or a bottom-antibottom-quark pair. The second search targets the pair production of higgsinos, with each higgsino decaying into a gravitino and a Higgs boson, which in turn is required to decay into a bottom-antibottom-quark pair. Both searches employ state-of-the-art experimental techniques and analysis strategies at the LHC, resulting in some of the most restrictive bounds available to date on the masses of the gluino,neutralino, and higgsino in the context of the models explored.