Probing Top Quark And Higgs Boson Production In Multijet Events At The Lhc With The Atlas Detector
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Probing Top Quark And Higgs Boson Production In Multijet Events At The Lhc With The Atlas Detector
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Author : Claudia Bertella
language : en
Publisher:
Release Date : 2013
Probing Top Quark And Higgs Boson Production In Multijet Events At The Lhc With The Atlas Detector written by Claudia Bertella 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.
Probing top quark and Higgs boson production in multi-jet avents at the LHC with the Atlas detector.The Atlas detector is a general purpose detector located at the Large Hadron Collider (LHC). It aims at the discovery af new physics phenomena and improving our knowledge of the standart Model (SM).
Search For Scalar Top Quarks And Higgsino Like Neutralinos
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Author : Takuya Nobe
language : en
Publisher: Springer
Release Date : 2015-11-30
Search For Scalar Top Quarks And Higgsino Like Neutralinos written by Takuya Nobe and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-11-30 with Science categories.
This book reports a search for theoretically natural supersymmetry (SUSY) at the Large Hadron Collider (LHC). The data collected with the ATLAS detector in 2012 corresponding to 20 /fb of an integrated luminosity have been analyzed for stop pair production in proton–proton collisions at a center-of-mass energy of 8 TeV at the Large Hadron Collider (LHC) in the scenario of the higgsino-like neutralino. The author focuses on stop decaying into a bottom quark and chargino. In the scenario of the higgsino-like neutralino, the mass difference between charginos and neutralinos (Δm) is expected to be small, and observable final-state particles are likely to have low-momentum (soft). The author develops a dedicated analysis with a soft lepton as a probe of particles from chargino decay, which suppresses the large amount of backgrounds. As a result of the analysis, no significant SUSY signal is observed. The 95% confidence-level exclusion limits are set to masses of stop and neutralino assuming Δm = 20 GeV. The region with ΔM (the mass difference between stop and neutralino) 70 GeV is excluded for the first time at stop mass of less than 210 GeV. The author also excludes the signals with ΔM 120 GeV up to 600 GeV of stop mass with neutralino mass of less than 280 GeV. The author clearly shows very few remaining parameter spaces for light stop (e.g., topology of stop decay is extremely similar to the SM top quark) by combining his results and previous ATLAS analyses. His results provide a strong constraint to searches for new physics in the future.
Phenomena Beyond The Standard Model What Do We Expect For New Physics To Look Like
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Author : Roman Pasechnik
language : en
Publisher: Frontiers Media SA
Release Date : 2020-09-03
Phenomena Beyond The Standard Model What Do We Expect For New Physics To Look Like written by Roman Pasechnik and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-09-03 with Science categories.
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Cern Courier
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Author :
language : en
Publisher:
Release Date : 2016
Cern Courier written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Nuclear energy categories.
Search For New Physics In Tt Final States With Additional Heavy Flavor Jets With The Atlas Detector
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Author : Javier Montejo Berlingen
language : en
Publisher: Springer
Release Date : 2016-07-20
Search For New Physics In Tt Final States With Additional Heavy Flavor Jets With The Atlas Detector written by Javier Montejo Berlingen and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-07-20 with Science categories.
This doctoral thesis focuses on the search for new phenomena in top-antitop quark (tt) final states with additional b-quark jets at the LHC. It uses the full Run 1 dataset collected by the ATLAS experiment in proton-proton collisions at √s=8 TeV. The final state of interest consists of an isolated lepton, a neutrino and at least six jets with at least four b-tagged jets, a challenging experimental signature owing to the large background from tt+heavy-flavor production. This final state is characteristic of ttH production, with the Higgs boson decaying into bb, a process that allows direct probing of the top-Higgs Yukawa coupling. This signature is also present in many extensions of the Standard Model that have been proposed as solutions to the hierarchy problem, such as supersymmetry or composite Higgs models, which predict the pair production of bosonic or fermionic top quark partners, or the anomalous production of four-top-quark events. All these physics processes have been searched for using an ambitious search strategy that has been developed on the basis of a combination of state-of-art theoretical predictions and a sophisticated statistical analysis to constrain in-situ the large background uncertainties. As a result, the most restrictive bounds to date on the above physics processes have been obtained.
Atlas Measurements Of The Higgs Boson Coupling To The Top Quark In The Higgs To Diphoton Decay Channel
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Author : Jennet Elizabeth Dickinson
language : en
Publisher: Springer
Release Date : 2021-11-17
Atlas Measurements Of The Higgs Boson Coupling To The Top Quark In The Higgs To Diphoton Decay Channel written by Jennet Elizabeth Dickinson and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-11-17 with Science categories.
During Run 2 of the Large Hadron Collider, the ATLAS experiment recorded proton-proton collision events at 13 TeV, the highest energy ever achieved in a collider. Analysis of this dataset has provided new opportunities for precision measurements of the Higgs boson, including its interaction with the top quark. The Higgs-top coupling can be directly probed through the production of a Higgs boson in association with a top-antitop quark pair (ttH). The Higgs to diphoton decay channel is among the most sensitive for ttH measurements due to the excellent diphoton mass resolution of the ATLAS detector and the clean signature of this decay. Event selection criteria were developed using novel Machine Learning techniques to target ttH events, yielding a precise measurement of the ttH cross section in the diphoton channel and a 6.3 $\sigma$ observation of the ttH process in combination with other decay channels, as well as stringent limits on CP violation in the Higgs-top coupling.
Search For The Associated Production Of Higgs Boson And Top Quark Pairs In Multijet Events And Calibration Of The B Jet Trigger For The Atlas Detector At The Lhc
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Author : Giovanni Bartolini
language : en
Publisher:
Release Date : 2020
Search For The Associated Production Of Higgs Boson And Top Quark Pairs In Multijet Events And Calibration Of The B Jet Trigger For The Atlas Detector At The Lhc written by Giovanni Bartolini and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Search For New Phenomena In Top Antitop Quarks Final States With Additional Heavy Flavour Jets With The Atlas Detector
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Author : Daiki Yamaguchi
language : en
Publisher: Springer Nature
Release Date : 2019-10-30
Search For New Phenomena In Top Antitop Quarks Final States With Additional Heavy Flavour Jets With The Atlas Detector written by Daiki Yamaguchi and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-10-30 with Science categories.
This book reports on the search for a new heavy particle, the Vector-Like Top quark (VLT), in the Large Hadron Collider (LHC) at CERN. The signal process is the pair production of VLT decaying into a Higgs boson and top quark (TT→Ht+X, X=Ht, Wb, Zt). The signal events result in top–antitop quarks final states with additional heavy flavour jets. The book summarises the analysis of the data collected with the ATLAS detector in 2015 and 2016. In order to better differentiate between signals and backgrounds, exclusive taggers of top quark and Higgs boson were developed and optimised for VLT signals. These efforts improved the sensitivity by roughly 30%, compared to the previous analysis. The analysis outcomes yield the strongest constraints on parameter space in various BSM theoretical models. In addition, the book addresses detector operation and the evaluation of tracking performance. These efforts are essential to properly collecting dense events and improving the accuracy of the reconstructed objects that are used for particle identification. As such, they represent a valuable contribution to data analysis in extremely dense environments.
Search For The Higgs Boson Produced In Association With Top Quarks With The Cms Detector At The Lhc
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Author : Cristina Martin Perez
language : en
Publisher: Springer Nature
Release Date : 2022-02-09
Search For The Higgs Boson Produced In Association With Top Quarks With The Cms Detector At The Lhc written by Cristina Martin Perez and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-02-09 with Science categories.
In this work, the interaction between the Higgs boson and the top quark is studied with the proton-proton collisions at 13 TeV provided by the LHC at the CMS detector at CERN (Geneva). At the LHC, these particles are produced simultaneously via the associate production of the Higgs boson with one top quark (tH process) or two top quarks (ttH process). Compared to many other possible outcomes of the proton-proton interactions, these processes are very rare, as the top quark and the Higgs boson are the heaviest elementary particles known. Hence, identifying them constitutes a significant experimental challenge. A high particle selection efficiency in the CMS detector is therefore crucial. At the core of this selection stands the Level-1 (L1) trigger system, a system that filters collision events to retain only those with potential interest for physics analysis. The selection of hadronically decaying τ leptons, expected from the Higgs boson decays, is especially demanding due to the large background arising from the QCD interactions. The first part of this thesis presents the optimization of the L1 τ algorithm in Run 2 (2016-2018) and Run 3 (2022-2024) of the LHC. It includes the development of a novel trigger concept for the High-Luminosity LHC, foreseen to start in 2027 and to deliver 5 times the current instantaneous luminosity. To this end, sophisticated algorithms based on machine learning approaches are used, facilitated by the increasingly modern technology and powerful computation of the trigger system. The second part of the work presents the search of the tH and ttH processes with the subsequent decays of the Higgs boson to pairs of τ lepton, W bosons or Z bosons, making use of the data recorded during Run 2. The presence of multiple particles in the final state, along with the low cross section of the processes, makes the search an ideal use case for multivariant discriminants that enhance the selectivity of the signals and reject the overwhelming background contributions. The discriminants presented are built using state-of-the-art machine learning techniques, able to capture the correlations amongst the processes involved, as well as the so-called Matrix Element Method (MEM), which combines the theoretical description of the processes with the detector resolution effects. The level of sophistication of the methods used, along with the unprecedented amount of collision data analyzed, result in the most stringent measurements of the tH and ttH cross sections up to date.
Top Quark Pair Production
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Author : Anna Christine Henrichs
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-10-04
Top Quark Pair Production written by Anna Christine Henrichs and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-04 with Science categories.
Before any kind of new physics discovery could be made at the LHC, a precise understanding and measurement of the Standard Model of particle physics' processes was necessary. The book provides an introduction to top quark production in the context of the Standard Model and presents two such precise measurements of the production of top quark pairs in proton-proton collisions at a center-of-mass energy of 7 TeV that were observed with the ATLAS Experiment at the LHC. The presented measurements focus on events with one charged lepton, missing transverse energy and jets. Using novel and advanced analysis techniques as well as a good understanding of the detector, they constitute the most precise measurements of the quantity at that time.