Observation of Single Top Quark with Associated Z Boson Production at the Large Hadron Collider Using the ATLAS Detector PDF Download
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Author: Dylan Frizzell
Publisher:
ISBN:
Category : Detectors
Languages : en
Pages : 154
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Book Description
Author: Dylan Frizzell
Publisher:
ISBN:
Category : Detectors
Languages : en
Pages : 154
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Book Description
Author: Bradley D. Schoenrock
Publisher:
ISBN: 9781369179101
Category : Electronic dissertations
Languages : en
Pages : 122
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Book Description
Author: Dag Gillberg
Publisher: Springer Science & Business Media
ISBN: 1441977996
Category : Science
Languages : en
Pages : 149
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Book Description
The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking—the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. It documents one of the flagship measurements of the D0 experiment, a collaboration of more than 600 physicists from around the world. It describes first observation of a physical process known as “single top quark production”, which had been sought for more than 10 years before its eventual discovery in 2009. Further, his thesis describes, in detail, the innovative approach Dr. Gillberg took to this analysis. Through the use of Boosted Decision Trees, a machine-learning technique, he observed the tiny single top signal within an otherwise overwhelming background. This Doctoral Thesis has been accepted by Simon Fraser University, Burnaby, BC, Canada.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
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Book Description
The cross-section for the production of a single top quark in association with a W boson in proton-proton collisions at √s = 8 is measured. The dataset corresponds to an integrated luminosity of 20.3 fb-1, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central b-jet are selected. The Wt signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of Wt events is observed with a significance of 7.7[sigma]. The cross-section is extracted in a profile likelihood fit to the classifier output distributions. The Wt cross-section, inclusive of decay modes, is measured to be 23.0±1.3(stat.)-3.5+3.2(syst.)±1.1(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element.
Author: Daiki Yamaguchi
Publisher: Springer Nature
ISBN: 9811509328
Category : Science
Languages : en
Pages : 279
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Book Description
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.
Author: Andre Milton Bach
Publisher:
ISBN:
Category :
Languages : en
Pages : 260
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Book Description
A search with the ATLAS detector for the pair production of a new b' quark in the Z boson plus b quark decay channel is reported. The pp collision data comprise 4.7 fb-1 of integrated luminosity at sqrt(s) = 7 TeV collected at the CERN Large Hadron Collider in 2011. This search complements recent searches for a b' decaying to a W boson and a top quark, and it is particularly important for new physics models containing vector-like quarks. From events containing both a Z boson reconstructed from electrons and a b tagged jet, any potential signal is enriched by selecting a subsample with large b' candidate pT. No evidence for a b' signal is found in this subsample; the invariant mass spectrum of the b' candidate agrees well with the Standard Model prediction. For the case of a b' that decays only to Z + b, masses mb'
Author: Amitava Datta
Publisher: Springer Science & Business Media
ISBN: 8184892950
Category : Science
Languages : en
Pages : 260
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Book Description
In an epoch when particle physics is awaiting a major step forward, the Large Hydron Collider (LHC) at CERN, Geneva will soon be operational. It will collide a beam of high energy protons with another similar beam circulation in the same 27 km tunnel but in the opposite direction, resulting in the production of many elementary particles some never created in the laboratory before. It is widely expected that the LHC will discover the Higgs boson, the particle which supposedly lends masses to all other fundamental particles. In addition, the question as to whether there is some new law of physics at such high energy is likely to be answered through this experiment. The present volume contains a collection of articles written by international experts, both theoreticians and experimentalists, from India and abroad, which aims to acquaint a non-specialist with some basic issues related to the LHC. At the same time, it is expected to be a useful, rudimentary companion of introductory exposition and technical expertise alike, and it is hoped to become unique in its kind. The fact that there is substantial Indian involvement in the entire LHC endeavour, at all levels including fabrication, physics analysis procedures as well as theoretical studies, is also amply brought out in the collection.
Author: Mesut Ünal
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis describes a search for new, heavy fermions using LHC data collected in 2015-2018 with the ATLAS detector. A search for single production of a vector-like top quark (VLT) decaying to a Z boson and a top quark in the dilepton final state is presented. This high statistics decay channel has high discovery potential thanks to the possibility of VLT mass reconstruction using the Z boson and top quark masses. The top quark decaying from a VLT is typically found in highly boosted, large-radius hadronic jets, which makes the identification challenging. To overcome this, novel top quark candidate identification techniques have been developed using the substructure information of variable-radius re-clustered jets. Variable-radius re-clustering uses large jets within a cone of momentum-dependent radius. The substructure information most sensitive to the top quark identification includes the mass, transverse momentum, and number of jet constituents. In this thesis, a detailed statistical analysis of the results of the search for VLT is presented. No deviation from the Standard Model is observed. The strongest to date observed and expected limits on the vector-like top mass as a function of coupling constant are set. In the case of VLT singlets with a coupling of kappa = 0.5, masses below 1810 GeV are excluded at the 95% confidence level
Author: Sebastian Mergelmeyer
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author: Herwig Schopper
Publisher: Springer Nature
ISBN: 3030382079
Category : Heavy ions
Languages : en
Pages : 632
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Book Description
This first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access
