Dissertations / Theses: 'S-TOP'

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Chavda, Vikash. "Measurement of the mass difference between top and anti-top quarksin top pair events from pp collisions at √s = 7 TeV." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/measurement-of-the-mass-difference-between-top-and-antitop-quarksin-top-pair-events-from-boldmathpp-collisions-at-boldmathsqrts--7tev(51cb834b-7dbb-4acd-b173-da025603dfc2).html.

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A measurement of the mass difference between top and anti-top quarks produced in $pp$ collisions at $\sqrt{s}=7$ TeV with the ATLAS detector at the LHC is presented. The analysis uses the full 2011 data sample, corresponding to an integrated luminosity of 4.7 fb$^{-1}$. An event-by-event mass difference is calculated for every event consistentwith $\ttbar$ production and decay in the semi-leptonic channel.A likelihood fit to the full double $b$-tagged data set yields a measured valueof $\Delta(m) = m_{t}-m_{\bar{t}} = 0.67 \pm{0.61}~(\mathrm{stat.}) \pm{0.19}~(\mathrm{syst.})~\mathrm{GeV}$, consistent with the Standard Model, and more generally, the CPT Theorem, prediction of no mass difference.

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Remiš, Ivo. "Marketingová strategie pro společnost TOP servis spol. s r.o." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2015. http://www.nusl.cz/ntk/nusl-225328.

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This master´s thesis focuses on the changes of marketing strategy for the company TOP servis s r. o. by using content marketing. The work describes realization of content marketing and there are also included amounts of money for publication of content. At the end there are discussed advantages and disadvantages of content marketing applied on this company.

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Farhat, Baber Khan. "Search for the top quark at [radical]s=1.8 TeV." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/26857.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1994.
On t.p., "[radical]" appears as the square root symbol.
Includes bibliographical references (leaves 157-162).
by Baber Khan Farhat.
Ph.D.

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Neep, Thomas James. "A measurement of spin correlation in top anti-top pairs and a search for top squarks at √s=8 TeV using the ATLAS detector." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/a-measurement-of-spin-correlation-in-top-antitop-pairs-and-a-search-for-top-squarks-at-sqrts8-tev-using-the-atlas-detector(cfb7f020-f0b5-4040-a17c-cde6dcc8d08d).html.

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The first measurement of the spin correlation strength in pairs of top quarks at √s=8 TeV is presented, using data collected using the ATLAS detector, corresponding to an integrated luminosity of 20.3 fb⁻¹. Dileptonically decaying tt^- events are selected with two high-pT leptons and at least two jets, one of which is required to be b-tagged. The azimuthal angle between the two charged leptons, Δφ, is used to measure the degree of spin correlation of top quark pairs. The extracted value of fSM, which is a measure of the spin-correlation strength, is fSM=1.20 ± 0.14. This is the most precise spin-correlation measurement to date. Using the Δφ distribution, a search for Supersymmetric top squarks is performed, with the assumption that the top squarks decay to a top quark and a neutralino. No excess of events is observed and top squarks with masses between the top quark mass and 191 GeV are excluded at 95% confidence level, extending previous limits.

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Manuitt, Alvaro Camacho. "CO₂ top of the line corrosion in the presence of H₂S." Ohio : Ohio University, 2006. http://www.ohiolink.edu/etd/view.cgi?ohiou1155043955.

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Hartwig, Fredrik. "Four Papers on Top Management´s Capital Budgeting and Accounting Choices in Practice." Doctoral thesis, Företagsekonomiska institutionen, Uppsala universitet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:du-12551.

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Rieck, Patrick. "Measurement of s-channel single top-quark production with the ATLAS detector using total event likelihoods." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17620.

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Es wird eine Messung der s-Kanal Einzel Top-Quark Produktion in Proton-Proton Kollisionen bei einer Schwerpunktsenergie von 8 TeV vorgestellt. Der verwendete Datensatz wurde mit dem ATLAS Detektor am LHC aufgenommen und entspricht einer integrierten Luminosität von 20.3 inversen Femtobarn. Kollisionsereignisse werden selektiert, sodass der resultierende Anteil der Signalereignisse relativ hoch ist. Selektierte Ereignisse enthalten ein isoliertes Elektron oder Myon, fehlenden Transversalimpuls und zwei Jets, die durch b-Quarks induziert wurden. Alle Objekte haben hohe transversalimpulse. Auch nach dieser Selektion überwiegen Untergrundprozesse, insbesondere die Paarproduktion von Top-Quarks und die Produktion von W-Bosonen begleitet von Jets. Um den Signalprozess weiter von den Untergründen zu trennen, werden mehrere Wahrscheinlichkeitsdichten näherungsweise berechnet. Sie unterscheiden sich hinsichtlich der Annahme des zugrundeliegenden Streuprozesses. Zusammen ergeben sie eine Funktion der gemessenen Impulse, mit deren Hilfe das Signal weiter von den Untergründen getrennt werden kann. Ein statistisches Modell der entsprechenden Verteilung wird an die Messdaten angepasst. Diese Messung ergibt eine Signifikanz des Signalprozesses von 3.4 Standardabweichungen und einen totalen Wirkungsquerschnitt von 5.3^+1.8_-1.6 Pikobarn. Dies ist die erste signifikante Messung der s-Kanal Einzel Top-Quark Produktion in Proton-Proton Kollisionen. Die Ergebnisse stimmen mit der Vorhersage des Standardmodells überein.
A measurement of s-channel single top-quark production in proton-proton collisions at a centre-of-mass energy of 8 TeV is presented. The data set has been recorded with the ATLAS detector at the LHC and corresponds to an integrated luminosity of 20.3 inverse femtobarn. Collision events are selected so that a subset of the data is obtained where the signal fraction is relatively high. Selected events contain one isolated electron or muon, missing transverse momentum and 2 jets, both of which are induced by b-quarks. All of these objects have large transverse momenta. The resulting set of events is still dominated by background processes, most notably top-quark pair production and the production of W bosons in association with jets. In order to further separate the signal from the backgrounds, several approximate event likelihoods are computed. They are based on different hypotheses regarding the scattering process at hand. Together they result in a function of the measured momenta which allows for the desired separation of the signal process. A statistical model of the corresponding distribution is used in a fit to the measured data. The fit results in a signal significance of 3.4 standard deviations and a total cross section of 5.3^+1.8_-1.6 picobarn. This is the first evidence for s-channel single top-quark production in proton-proton collisions. The results agree with the standard model prediction.

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Vlimant, Jean-Roch. "Mesure de la section efficace de production de paires de quarks top / anti-top dans des collisions protons / anti-protons à √s[racine de s] égale à 1. 96 TeV auprès de l'expérience DØ." Paris 6, 2005. https://tel.archives-ouvertes.fr/tel-00011503.

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Gadfort, Thomas. "Evidence for electroweak top quark production in proton-antiproton collisions at sqrt(s) = 1.96 TeV /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9684.

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Yaakob, Najmiddin. "Top of the Line Corrosion in CO₂/H₂S Environments." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457.

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Tavares, Patrícia Isabel Ramos Pego Nunes. "Values “On-Air” : how the top management espoused values enter the stakeholder´s ethical reputation formation process." Doctoral thesis, Instituto Superior de Economia e Gestão, 2021. http://hdl.handle.net/10400.5/21696.

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Doutoramento em Gestão
Corporate reputation is an increasingly valuable intangible organisational asset. Reputation is perceptual, multidimensional, specific, and varies from stakeholder to stakeholder. However, there is still a lack of research in understanding the reputation-formation process. The social construction approach to reputation uses stakeholder theory to understand the process of forming a corporate reputation. Stakeholder theory recovers the central role of values in organisational strategy and sets the tone for the development of responsible management and responsible leadership. The organisational values adopted by the organisation's top management (espoused values) influence organisational dynamics. Still, studies on the connections of the values adopted by the top corporate management and their effects on internal and external stakeholders are scarce. This study aims to understand how the values embraced by the top management play a role in the formation of corporate reputation. With a qualitative processual approach and a narrative construction strategy, 62 in-depth interviews were conducted with the management of the largest national radio group and various internal and external stakeholders. Also, I collected archival data on cases and events identified in the interviews, in a total of 28 cases. This study presents a process that reveals how the salience of the values adopted by the top management (espoused values) enter the orgnisation's ethical reputation formation process.
A reputação corporativa é um ativo organizacional intangível cada vez mais importante. A reputação é percetual, multidimensional, específica e varia de stakeholder para stakeholder. No entanto, o processo de formação da reputação carece de mais investigação. A abordagem de construção social da reputação recorre à teoria de stakeholders para compreender o processo de formação da reputação corporativa. A teoria de stakeholders recupera o papel central dos valores na estratégia organizacional e, desta forma, define o tom para o desenvolvimento da gestão e da liderança responsável. Os valores organizacionais adotados pela gestão da organização influenciam a dinâmica organizacional, mas ainda são escassos os estudos sobre as relações dos valores adotados pela gestão organizacional e os seus efeitos nos stakeholders internos e externos à organização. O objetivo deste estudo é compreender como os valores adotados pela gestão desempenham um papel na formação da reputação corporativa. Com uma abordagem processual qualitativa, e uma estratégia de construção de narrativas, realizaram-se 62 entrevistas em profundidade, aos membros da administração do maior grupo de rádio nacional, e a diversos stakeholders internos e externos. Recolheram-se também dados sobre casos e eventos identificados nas entrevistas, num total de 28 casos. Este estudo apresenta um processo que revela a saliência dos valores adotados pela gestão, na construção da reputação ética da organização.
info:eu-repo/semantics/publishedVersion

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Monini, Caterina. "Mesure de la section efficace de production électrofaible de quark top en voie S, dans l'expérience ATLAS." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY037/document.

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Le travail présenté dans cette thèse a pour sujet la mesure du seul mécanisme de production électrofaible de quark top qui n'ait pas encore été observé au collisionneur hadronique du CERN (LHC): la voie-s. L'intérêt réside dans la confirmation des prédictions du Modèle Standard, mais le but est aussi de contraindre plusieurs scénarios de nouvelle physique à partir de la combinaison de la section efficace voie-s avec celle des autres canaux de production single top, la voie-t et Wt. Après une introduction générale sur la physique du quark top et les dispositifs expérimentaux visant à la détection et la reconstruction des objets physiques, on présente deux analyses réalisées des données de collisions proton-proton enregistrées par le détecteur ATLAS `a une énergie dans le centre de masse de 7 et 8 TeV. Etant donné que la production de quark top en voie-s est caractérisée par une tr`es faible pureté et que, en même temps, elle est défavorisée au LHC puisque elle a lieu par annihilation quark-antiquark, une technique multi variée a été appliquée dans les deux cas afin de discriminer le signal. Pour l' étude à 7 TeV, relatif à une luminosité intégrée de 4.7 $fb^{-1}$, deux classificateurs basés sur des arbres de décision boostés sont entrainés contre les événements de bruits de fond principaux; une coupure appliquée sur un des discriminateurs met en oeuvre une sélection des événements, la distribution issue de l'autre discriminateur est ensuite employée dans un fit de maximum de vraisemblance. Cela permet de d'eriver une limite supérieure sur la section efficace voie-s de 21.5 pb (14.3 pb attendu), correspondant à une portée de 0.6 déviations standard (0.8 attendu). L'analyse à 8 TeV, qui est basée sur une luminosité intégrée de 20.3 $fb^{-1}$, repose sur une strat'egie plus simple: seulement un classificateur BDT est optimisé pour isoler le signal, après une préalable sélection des événements grâce `a de simples coupures. Sa distribution discriminante est ensuite ajustée aux données selon la même approche qu' `a 7 TeV, en considérant les incertitudes systématiques et statistiques pendant la génération de pseudo expériences. La portée de la mesure étant encore inférieure à trois déviations standard (1.5 $sigma$ observé et 1.4 attendu), seule une limite `a 95% C.L. peut être établie sur la section efficace; le résultat correspond `a 15.7 pb (7.9 pb attendu)
The work reported in this thesis is aimed at measuring with the ATLAS detector theonly mechanism of top quark electroweak production which has not yet been observedat the Large Hadron Collider: the s-channel. Its interest relies in the confirmationof the Standard Model predictions but, as well, in the possibility of constraining severalnew physics scenarios when comparing the s-channel cross section with the oneof the other single top production modes (the Wt and t-channel). After a generalintroduction upon top physics and the experimental setup employed for the detectionand the reconstruction of the physics objects, we present two analyses realizedwith proton-proton collisions collected by the ATLAS detector at a center of massenergy of 7 and 8 TeV. Since the s-channel production is characterized by a verylow purity and, at the same time, is not favoured at the LHC because it proceedsvia quark-antiquark annihilation, a multivariate approach is applied in both cases todiscriminate the signal. For the 7 TeV study, based on an integrated luminosity of4.7 fb−1, two boosted decision trees classifiers are optimized against the main sourcesof background; a cut realized on one of such discriminants implements a tight eventselection, after which the second output distribution is used for a maximum likelihoodfit to the data. This allows to set an upper limit on the s-channel cross section of21.5 pb (14.3 pb expected), corresponding to a significance of 0.6 standard deviations(0.8 expected). The 8 TeV analysis, based on an integrated luminosity of 20.3 fb−1,has a simpler strategy: only one boosted decision trees classifier is trained to isolatesignal after a preliminary cut-based selection; its output distribution is then fitted tothe data with the same approach than at 7 TeV, taking into account the systematicand statistical uncertainty via the generation of pseudoexperiments. The significanceof the s-channel measurement being lower than 3 σ (1.3 standard deviation observed,1.4 expected), only a 95% C.L. limit can be set on the cross section; the result ishowever improved and corresponds to 14.6 pb (7.9 pb expected).3

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Friedrich, Conrad. "Search for single top-quark production via flavour-changing neutral currents in strong interactions using s = 8 TeV ATLAS data." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2015. http://dx.doi.org/10.18452/17348.

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In dieser Dissertation werden Resultate einer Suche nach der Produktion von Einzel-Top-Quarks über flavour-verletzende neutrale Ströme (FCNCs) in starken Welchselwirkungen vorgestellt. Hierfür werden Daten aus Proton-Proton-Kollisionen am Large Hadron Collider bei einer Schwerpunktsenergie von 8TeV verwendet. Die Daten wurden mit dem ATLAS-Experiment im Jahr 2012 aufgenommen und entsprechen einer integrierten Luminosität von 14.1 fb−1. In der Analyse werden FCNC-Ereignisse selektiert, in denen ein leichtes Quark (u oder c) mit einem Gluon wechselwirkt, und ein einzelnes Top-Quark und potentiell ein weiterer einzelner Jet produziert wird. Mittels der Forderung nach genau einem Myon oder Elektron, großer fehlender Transversalenergie und exakt einem Bottom-Quark-Jet und eventuellem zusätzlichen Jet im Endzustand werden Kandidaten der gesuchten Ereignisse im leptonischen Zerfallskanal des Top-Quarks selektiert. Zur Unterscheidung zwischen Signal- und Untergrundereignissen werden multivariate Methoden herangezogen. Künstliche neuronale Netze werden verwendet, um diverse kinematische Variablen zu einem einzelnen Klassifikator zu kombinieren. Um die potentielle Produktion von Top-Quarks über FCNCs zu quantifizieren, werden die Ausgaben der neuronalen Netze einer Bayes''schen statistischen Analyse unterzogen. Da kein Überschuss an Signalereignissen festgestellt werden kann und die Ergebnisse den Erwartungen der theoretischen Vorhersagen entsprechen, werden neue obere Schranken auf den FCNC-Produktionswirkungsquerschnitt von Einzel-Top-Quarks ermittelt. Aus diesen werden unter Verwendung von modell-unabhängigen theoretischen Berechnungen neue obere Schranken auf die Kopplungskonstanten sowie auf die entsprechenden Verzweigungsverhältnisse ermittelt.
This thesis presents results of a search for single top-quark production via flavour-changing neutral currents (FCNCs) in strong interactions using data recorded with the ATLAS experiment at the Large Hadron Collider in 2012. A dataset from proton-proton collisions at a centre-of-mass energy of 8TeV and corresponding to an integrated luminosity of 14.1 fb−1 is used. It is searched for FCNC events in which a light quark (u or c) interacts with a gluon to produce a single top quark, either with or without the associated production of another light quark or gluon. Candidate events of leptonically decaying top-quarks are selected by requiring a single electron or muon, a substantial amount of missing transverse energy, and exactly one or two jets of which exactly one has to fulfil a b-tagging criterion. Multivariate techniques are employed in order to distinguish between signal- and background-like events by making use of artificial neural networks that combine multiple kinematic variables into a single classifier output. A Bayesian statistical analysis is performed on the classifier outputs in order to quantify potential signs of FCNC single top-quark production. No excess in signal events is observed and the results are in agreement with the theory predictions. Consequently a new upper limit is set on the FCNC single top-quark production cross-section multiplied by the t->Wb branching fraction. Using theory calculations within a model-independent effective theory framework, this limit is converted into upper limits on the coupling constants of the FCNC interactions as well as into respective upper limits on the branching fractions.

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Eckardt, Christoph. "Jet activity in top-quark events at √s = 13 TeV using 3.2 fb-1 data collected by the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21053.

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In dieser Arbeit wird die Messung des normalisierten differentiellen Wechselwirkungsquerschnitts von Top Quark Produktionen mit zusätzlichen Jets präsentiert. Es werden Proton-Proton Kollisionsdaten des ATLAS Experiments am Large Hadron Collider bei einer Schwerpunktsenergie von 13 TeV mit einer Luminosität von 3.2 fb-1 verwendet. Die Top Quark Ereignissen werden durch ein entgegengesetzt geladenes Elektron-Muon Paar und zwei b-tagged Jets selektiert. Der differentielle Wechselwirkungsquerschnitt wird als Funktion von Observablen, die sensitiv auf zusätzliche Jets sind, gemessen: der Jetmultiplizität, des transversalen Impulses der zusätzlichen Jets, der Summe der transversalen Impulse aller Objekte im Ereignis und räumlichen Korrelationen zwischen den zwei Jets mit dem größten Impulsen. Die gemessenen Daten werden auf Teilchen-Level korrigiert und mit verschiedenen Vorhersagen für detailierte Studien des Monte Carlo QCD Models verglichen.
In this thesis, the measurement of the normalised differential cross-sections of top quark pair production in association with jets using 3.2 fb-1 of proton-proton col- lision data at a centre-of-mass energy of 13 TeV by the ATLAS experiment at the LHC are presented. Jets are selected from top events which are defined by an opposite-charge electron-muon pair and two b-tagged jets in the final state. The cross-sections are measured as functions of several observables are sensitive to ad- ditional jets: jet multiplicities, transverse momentum of additional jets, transverse momentum sum of all objects in the event and spatial correlations of the two high- est momentum additional jets. The data are corrected to obtain particle-level fidu- cial cross-section. The resulting measurements are compared to several predictions allowing detailed studies of Monte Carlo QCD modelling.

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Vlimant, Jean-Roch. "Mesure de la section éfficace de production de paires de quarks top/anti-top dans des collisions protons/anti-protons à \/s égale à 1.96 TeV auprès de l'expérience D0." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00011503.

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Le quark top (t) découvert en 1995, pourrait être le sujet de la manifestation de nouvelles interactions et sa production en paires ttbar est un bruit de fond pour la recherche de processus rares.
Le Tevatron, collisionneur proton/anti-proton avec une énergie dans le centre de masse de 1.96 TeV, produit des paires top/anti-top avec une section efficace théorique de 7 pb.
La section efficace de production ttbar est mesurée dans le canal "électron+jets" en utilisant une luminosité intégrée de 360 pb-1 prise avec le détecteur D0. Dans un lot enrichi en désintégrations électronique de bosons W, le nombre d'évènments de signal est estimé grâce à des critères topologiques. La mesure est 9.0 +/- 2.0 +/- 1.7 +/- 0.- pb.
La calibration des gains et des non-linéarités de l'électronique du calorimètre, essentiel à cette mesure, est effectuée. L'algorithme T42 est présenté, il permet une suppression du bruit électronique du calorimètre en conservant les signaux de plus de 4sigma et leurs voisins directs de plus de 2.5sigma.

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Aad, G., Richard Brenner, Claus P. Buszello, Tord Ekelöf, Mattias Ellert, Arnaud Ferrari, Charlie Isaksson, Daniel Pelikan, and L. Zwalinski. "Measurements of top quark pair relative differential cross-sections with ATLAS in pp collisions at root s=7 TeV." Uppsala universitet, Högenergifysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-201934.

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Measurements are presented of differential cross-sections for top quark pair production in pp collisions at root s = 7 TeV relative to the total inclusive top quark pair production cross-section. A data sample of 2.05 fb(-1) recorded by the ATLAS detector at the Large Hadron Collider is used. Relative differential cross-sections are derived as a function of the invariant mass, the transverse momentum and the rapidity of the top quark pair system. Events are selected in the lepton (electron or muon) + jets channel. The background-subtracted differential distributions are corrected for detector effects, normalized to the total inclusive top quark pair production cross-section and compared to theoretical predictions. The measurement uncertainties range typically between 10 % and 20 % and are generally dominated by systematic effects. No significant deviations from the Standard Model expectations are observed.

ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-012-2261-1

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Walter, Thorsten. "Search for electroweak single top quark production with CDF in proton antiproton collisions at s = 1.96 T E V." [S.l. : s.n.], 2005. http://swbplus.bsz-bw.de/bsz118344536abs.htm.

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Mogg, Philipp [Verfasser], Christian [Akademischer Betreuer] Weiser, and Karl [Akademischer Betreuer] Jakobs. "The search for top-squark pair production with the ATLAS detector at √s = 13 TeV in the fully hadronic final state = The search for top-squark pair production with the ATLAS detector at [square root]s = 13 TeV in the fully hadronic final state." Freiburg : Universität, 2019. http://d-nb.info/1217193669/34.

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Levy, Mark. "Inclusive and differential measurements of spin correlation in top-antitop quark pairs at √s = 8 TeV using the ATLAS detector." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6995/.

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A measurement of the spin correlation strength in top-antitop pairs is presented, using protonproton collision data collected at the ATLAS detector with a centre of mass energy of √s = 8 TeV and an integrated luminosity of 20.3 fb$^{-1}$. An inclusive measurement is made, as well as a differential measurement as a function of the top-antitop invariant mass. Additionally, these measurements are made both at detector level and unfolded to a parton level distribution. Selected events are required to have exactly two oppositely charged leptons (either electrons or muons), a large missing transverse energy and at least two hadronic jets, at least one of which must be tagged as originating from a b-quark. The azimuthal separation between the two charged leptons, Δφ, is used to measure the degree of spin correlation. The measured distribution is compared to a Standard Model prediction and a model with no spin correlation. It is found that the results all favour the Standard Model prediction over the uncorrelated model, with the data found to be several standard deviations away from the uncorrelated scenario.

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Wang, Jin. "Mesure de la section efficace de production du single top en voie-t en utilisant des arbres de décision avec ATLAS à sqrt(s)=7 TeV." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00716925.

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Cette thèse présente une mesure de la section efficace de production du quark-top célibataire en voie t avec 1.04 fb-1 de données recueillies par le détecteur ATLAS au LHC à partir de collisions proton-proton d' énergie centre de masse sqrt(s) = 7 TeV. Les événements sélectionnés contiennent un lepton, de l'énergie transverse manquante, et deux ou trois jets, l'un d'eux étant étiqueté comme étant issu d'un quark-b. Le modèle pour le bruit de fond se compose des processus multijets, W+jets et production de paires de quarks top ainsi que de contributions moindres venant d' événements Z+jets et diboson. En utilisant une sélection basée sur la distribution d'un discriminant multivarié construit avec des arbres de décision stimulés, la section efficace de production de quark-top célibataire en voie t a été mesurée. La valeur de 97.3+30.7-30.2 pb a été obtenue. Ce résultat est en bon accord avec la prédiction du Modèle Standard. En supposant que les éléments de la matrice CKM reliée au quark-top obéissent à la relation |Vtb|>>|Vts|, jVtd|, la force du couplage W-t-b est extraite à partir de la section efficace mesurée, |Vtb| = 1.23+0.20-0:19. Si on suppose que |Vtb| <= 1, une limite inférieure |Vtb| > 0.61 est obtenue avec un niveau de confiance de 95%.

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Alhroob, Muhammad [Verfasser]. "Search for Flavour Changing Neutral Currents in Single Top-Quark Production at √s = 7 TeV with the ATLAS Detector / Muhammad Alhroob." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1044869984/34.

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Sturm, Philipp [Verfasser]. "Measurement of the t-Channel Single Top-Quark Production Cross-Section with the ATLAS Detector at √s = 7 TeV / Philipp Sturm." Wuppertal : Universitätsbibliothek Wuppertal, 2012. http://d-nb.info/1029845875/34.

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Margaroli, Fabrizio <1976&gt. "Measurement of the top quark mass in the all-hadronic channel at proton antiproton collisions at √s = 1.96TeV with CDF II." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/348/.

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Hensel, C., K. Johns, X. Lei, R. Nayyar, and E. W. Varnes. "Measurement of spin correlation between top and antitop quarks produced in p(p)over-bar collisions at root s=1.96 TeV." ELSEVIER SCIENCE BV, 2016. http://hdl.handle.net/10150/616988.

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We present a measurement of the correlation between the spins of t and (t) over bar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the DO detector that correspond to an integrated luminosity of 9.7 fb(-1). The measured value of the correlation coefficient in the off-diagonal basis, O-off = 0.89 +/- 0.22 (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).

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Stănescu-Bellu, Mădălina. "Search for heavy Higgs bosons A/H decaying to a top-quark pair in pp collisions at \sqrt(s)=8 TeV with the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22839.

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In dieser Dissertation wird die Suche nach schweren neutralen pseudoskalaren A und skalaren H Higgs-Bosonen vorgestellt, die in gg-Fusionen erzeugt werden, und in ein Top-Antitop-Quark-Paar zerfallen. Gesucht wurde im vollständigen Datensatz von Proton–Proton-Kollisionen bei einer Schwerpunktsenergie von 8 TeV die vom ATLAS-Detektor am Large Hadron Collider aufgezeichnet wurde und einer integrierten Luminosität von 20.3 fb−1 entspricht. Der Signalprozess und der Haupthintergrund aus der Top-Quark-Paar-Produktion über starke gg-Fusionen-Prozesse, interferieren heftig, was zu einer Verzerrung des reinen Breit-Wigner-Resonanzpeak in eine Peak-Dip-Struktur führt. Diese Analyse ist die erste am LHC, die die Interferenz zwischen Signal und Hintergrundprozessen vollständig berücksichtigt. Die Suche stützt sich auf die statistische Analyse des invarianten Top-Quark-Paar-Massenspektrum, welches aus Ereignissen mit einem Elektron oder Myon mit hohem Transversalimpuls, einer hohen fehlenden Transversalenergie von dem nicht detektierten Neutrino und mindestens vier Jets rekonstruiert wird. In den Daten wird keine signifikante Abweichung vom erwarteten Standardmodell-Hintergrund beobachtet. Die Ausschließungsgrenzen wurden abgeleitet im Kontext des Typ II Two-Higgs-Doublet Model, für Higgs-Bosonen mit einer Masse von 500 und 750 GeV und mit niedrigerem tan(\beta)-Parameter, bei der tan(\beta) das Verhältnis der Vakuumerwartungswerte der beiden Higgs-Dublett-Felder ist. Diese Parameterregionen sind weitgehend unerforscht in Untersuchungen von beliebigen Endzuständen.
In this thesis a search is presented for heavy neutral pseudoscalar A and scalar H Higgs bosons, produced in gg fusion and decaying into a top-antitop quark pair. The search is conducted on the full proton-proton collisions dataset recorded by the ATLAS detector at the Large Hadron Collider at a centre-of-mass collision energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb−1. The signal process and the main background from top quark pair production via the gg fusion strong process, interfere heavily, distorting the signal shape from the pure Breit-Wigner resonance peak to a peak-dip structure. This analysis is the first one at the LHC that fully takes into account the interference between a signal and the background processes. The search relies on the statistical analysis of the top quark pair invariant mass spectrum, which is reconstructed in signal candidate events with a high-transverse momentum electron or muon, large missing transverse energy from the undetected neutrino and at least four jets. No significant deviation from the expected SM background is observed in data. Exclusion limits are derived in the context of the type-II Two-Higgs-Doublet Model, for Higgs boson masses of 500 and 750 GeV and in the low tan(\beta) parameter region, where tan(\beta) is the ratio of the vacuum expectation values of the two Higgs doublet fields. These parameter regions have been largely unexplored by searches in any final state.

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Stamm, Sören. "Combined Measurement of Single Top-Quark Production in the s and t-Channel with the ATLAS Detector and Effective Field Theory Interpretation." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19317.

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In dieser Arbeit wird eine kombinierte Messung der elektro-schwachen Produktion einzelner Top-Quarks im s- und t-Kanal vorgestellt. Der analysierte Datensatz von Proton-Proton-Kollisionsereignissen wurde im Jahr 2012 mit dem ATLAS Detektor am Large Hadron Collider bei einer Schwerpunktsenergie von 8 TeV aufgezeichnet und entspricht einer integrierten Luminosität von 20.3 fb^{-1}. Die Ereignisauswahl beschränkt sich auf Ereignisse mit einem isolierten Elektron oder Myon und zwei Jets. Mit Hilfe der Matrix Element Methode werden Prozess-Likelihoods berechnet. Aus diesen wird eine Diskriminante gebildet um Signal- und Untergrundereignisse voneinander zu trennen. Die Wirkungsquerschnitte für die Produktion einzelner Top-Quarks wurden mittels eines kombinierten Maximum Likelihoods Fits zu sigma_{s} = 4,9 +- 1,7 pb und sigma_{t} = 82,32^{+7,0}_{-5,5} pb bestimmt. Die Korrelation zwischen beiden Messungen beträgt 8%. Diese beiden Ergebnisse werden zusammen mit einer unabhängigen Messung der assoziierten Wt Produktion verwendet um zwei Parameter, cquer_{phiq} und cquer_{qq}, im Rahmen einer effektiven Feldtheorie zu bestimmen. Notwendige Akzeptanzkorrekturen wurden mit Hilfe schneller und vereinfachter Detektorsimulationen ermittelt. Diese Korrekturen werden in dem statistischen Modell zur Bestimmung der effektiven Feldtheorie-Parametern berücksichtigt. Die kleinsten Intervalle, welche 95,5% des gesamten Wahrscheinlichkeitsbereichs entsprechen, sind -0,132 < cquer_{phiq} < 0,048 und -0,0283 < cquer_{qq} < 0,0062 für die beiden Kopplungsparameter.
This thesis presents a combined measurement of single top-quark production in the s and t-channel with the ATLAS detector at the Large Hadron Collider. The 2012 data set of proton--proton collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb^{-1} is used. The event selection for both channels requires one isolated electron or muon and two jets in the final state. In order to separate signal from background events, a discriminant variable is built from likelihoods obtained with the matrix element method. The cross section for both channels are determined by a combined maximum likelihood fit, which yields sigma_{s} = 4.9 +- 1.7 pb and sigma_{t} = 82.32^{+7.0}_{-5.5} pb for the s-channel and t-channel, respectively. The correlation of the two cross section measurements is 8%. These results together with an independent measurement of the associated Wt production are used to set limits on two parameters, cbar_{phiq} and cbar_{qq}, within the framework of an effective field theory. Acceptance corrections are derived as a function of the model parameters by using fast and simplified detector simulations. These corrections are included in the statistical model and the smallest intervals that correspond to 95.5% probability are -0.132 < cbar_{phiq} < 0.048 and -0.0283 < cbar_{qq} < 0.0062 for the two parameters.

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Wang, Jin. "Mesure de la section efficace de production du single top en voie-t en utilisant des arbres de décision avec ATLAS à sqrt(s)=7TeV." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY034/document.

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Cette thèse présente une mesure de la section efficace de production du quark-top célibataire en voie t avec 1,04~fb^{-1} de données recueillies par le détecteur ATLAS au LHC à partir de collisions proton-proton d'énergie centre de masse sqrt(s) = 7TeV. Les événements sélectionnés contiennent un lepton, de l'énergie transverse manquante, et deux ou trois jets, l'un d'eux étant étiqueté comme étant issu d'un quark-b. Le modèle pour le bruit de fond se compose des processus multijets, W+jets et production de paires de quarks top ainsi que de contributions moindres venant d'événements Z+jets et diboson. En utilisant une méthode de coupures et de comptage basée sur la distribution d'un discriminant multivarié construit avec des arbres de décision stimulés, la section efficace de production de quark-top célibataire en voie t a été mesurée. La valeur sigma_ {t} = 97,3^{30,7}_{-30,2}~pb a été obtenue. Ce résultat est en bon accord avec la prédiction du Modèle Standard. En supposant que les éléments de la matrice CKM reliee au quark-top obéissent à la relation |Vtb|>>|Vts|, |V_td|, la force du couplage W-t-b est extraite de la section mesurée, |Vtb| = 1,23^{+0,20}_{-0,19}. Si on suppose que |Vtb|<1, une limite inférieure |Vtb|>0.61 est obtenue avec un niveau de confiance de 95%
This thesis presents a measurement of the cross section of t-channel single top-quark production using 1.04~fb^{-1} data collected by the ATLAS detector at the LHC with proton-proton collision at center-of-mass sqrt(s)=7TeV. Selected events contain one lepton, missing transverse energy, and two or three jets, one of them b-tagged. The background model consists of multijets, W+jets and top-quark pair events, with smaller contributions from Z+jets and diboson events. By using a cut and count method based on the distribution of a multivariate discriminant constructed with the boosted decision trees, the cross section of t-channel single top-quark production is measured: sigma_{t}= 97.3^{+30.7}_{-30.2}~pb, which is in good agreement with the prediction of the Standard Model. Assuming that the top-quark-related CKM matrix elements obey the relation |Vtb|>>|Vts|, |V_td|, the coupling strength at the W-t-b vertex is extracted from the measured cross section, |Vtb| = 1,23^{+0,20}_{-0,19}. If it is assumed that |Vtb|<1, a lower limit of |Vtb|>0.61 is obtained at the 95% confidence level

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Vishwakarma, Akanksha. "Cross-section measurement of top quark pair production with additional b-jets in the eμ channel at √ s = 13 TeV with the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20757.

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Diese Doktorarbeit behandelt die Messung des Wirkungsquerschnittes der Paarbildung von Top-Quarks mit zusätzlichen B-Jets (Teilchenschauer aus der Fragmentierung von B-Quarks) in Proton-Proton-Kollisionen bei einer Schwerpunktsenergie von √s =13 TeV am Large Hadron Collider. Der Datensatz wurde 2015/16 mit dem ATLAS-Detektor aufgezeichnet und entspricht einer integrierten Luminosität von 36,1/fb. Die Wirkungsquerschnitte werden auf Teilchenebene in einem fiduziellen Phasenraum gemessen, der dicht an der Detektorakzeptanz gewählt wurde. Die fiduziellen inklusiven Wirkungsquerschnitte für tt-Endzustände mit mindestens einem oder mindestens zwei zusätzlichen B-Jet(s) nach Abzug der Beiträge von ttH(bb) und ttZ(bb) werden als 177 ± 5(stat) ± 24(syst) fb bzw. 25 ± 3(stat) ± 7(syst) fb bestimmt. Die Messungen werden mit dem neusten Stand von unterschiedlichen theoretischen Vorhersagen verglichen. Im Allgemeinen sind die gemessenen inklusiven, fiduziellen Wirkungsquerschnitte größer als die ttbb-Vorhersagen von verschiedenen NLO-Berechnungen des mit Partonschauern abgeglichenen tt-Matrixelements, bleiben aber im Rahmen der Messunsicherheit. Die Unsicherheiten der experimentellen Messung sind kleiner als die Unsicherheiten der Vorhersagen. Die differenzielle Messung von tt+B-Jets wird mit dieser Analyse zum ersten Mal innerhalb der ATLAS-Kollaboration durchgeführt. Die normalisierten differenziellen Wirkungsquerschnitte werden als Funktion der Multiplizität der B-Jets, kinematischen Ereignisobservablen und Observablen der Objekte in den Endzuständen dargestellt. Die beobachteten differenziellen Verteilungen werden mit einer Vielzahl an theoretischen Vorhersagen verglichen und eine gute Übereinstimmung mit den Daten für die meisten festgestellt.
This thesis presents the cross-section measurement of top quark pair (tt) production in association with additional b-jets (tt+b-jets) in proton-proton collisions at a centre-of-mass energy, √s = 13 TeV at the Large Hadron Collider. The analysis is performed in the emu decay channel of tt using a dataset comprising an integrated luminosity of 36.1/fb collected by the ATLAS detector in the years 2015 and 2016. The cross-sections are measured at particle level in a fiducial phase space which is chosen close to the detector acceptance. The fiducial inclusive cross-section for tt final states with at least one and at least two additional b-jet(s) is measured to be 177 ± 5(stat) ± 24(syst) fb and 25 ± 3(stat) ± 7(syst) fb, respectively, after subtracting the contributions from ttH(bb) and ttZ(bb). Comparison of the measured cross-section to various state-of-the-art theoretical QCD predictions are made. The measured inclusive fiducial cross-sections generally exceed the ttbb predictions from various NLO matrix element calculations matched to a parton shower but are compatible within the uncertainties. The experimental uncertainties in the measurement are smaller than the uncertainties in the predictions. The differential measurement of tt+b-jets is carried out for the first time by the ATLAS collaboration in this analysis. The normalised differential cross-sections as a function of b-jet multiplicity, kinematic observables of the events and properties of b-jet pairs are shown. The observed differential distributions are compared with multitude of theoretical predictions and a good agreement with data is found for most of them.

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Tsiskaridze, Shota. "Search for avor-changing neutral current top quark decays t—›Hq, with H—›bb, in pp collisions at √s = 8 TeV with the ATLAS detector." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/387229.

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Esta tesis presenta la búsqueda de decaimientos del quark top, via corrientes neutras que cambian el sabor, a quarks tipo u (q = u; c) y a el bosón de Higgs del modelo estándar. El análisis busca eventos donde un quark top decae a Wb y el W decae en leptones, mientras que el otro quark top decae a Hq. El estudio se basa en colisiones protón-protón a una energía en el centro de masa de √ s = 8 TeV obtenidas en 2012 con el detector ATLAS del Large Hadron Collider del CERN, usando una muestra de 20.3 fb-1. Los datos corresponden a eventos con un electrón o muon aislado y al menos cuatro jets en el estado final. La búsqueda explota la alta multiplicidad de quarks b que caracterizan la señal, empleando un discriminante basado en la verosimilitud que utiliza las diferencias cinemáticas entre la señal y el fondo (el cual está dominado por eventos tt—›WbWb). No se observan eventos en exceso del fondo esperado. Los límites de un 95% de confianza para el proceso observado (esperado) son de 0.56% (0.42%) para t —›Hc y de 0.61% (0.64%) para t—›Hu. Los límites de esta búsqueda han sido combinados con las búsquedas en los canales con modos de decaimiento H—› y H—›WW*; tt , logrando mejorar significativamente la sensibilidad. Los límites de un 95% de confianza para la combinación observada (esperada) es de 0.46% (0.25%) para t—› Hc y 0.45% (0.29%) para t ! Hu respectivamente. Los límites correspondientes en el acoplamiento | tcH| y | tuH| son de 0.13 (0.10) y 0.13 (0.10) respectivamente. Estos son los límites directos más restringidos en la búsqueda de interacciones tqH hasta el momento.
In this dissertation a search for avour-changing neutral currents in the decay of a top quark to an up-type quark (q = u; c) and the Standard Model Higgs boson, where the Higgs boson decays to bb, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb-1. Data are analyzed in the lepton+jets final state, characterized by an isolated electron or muon with moderately high transverse momentum and at least four jets. The search exploits the high multiplicity of b jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt—›WbWb decays. No significant excess of events above the background expectation is found. The observed (expected) upper limits on the t—›Hc and t—›Hu branching ratios are 0.56% (0.42%) and 0.61% (0.64%) respectively, at the 95% confidence level. The combination of this search with other ATLAS searches in the H—› and H—›WW*,tt decay modes significantly improves the sensitivity yielding observed (expected) upper limits on the t—›Hc and t—›Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively, at the 95% confidence level. The corresponding combined ob- served (expected) upper limits on the | tcH| and | tuH| couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds to date on tqH interactions measured so far.

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Roscher, Frank [Verfasser], and T. [Akademischer Betreuer] Müller. "Charge Asymmetry Measurements in Top Quark Pair Production at sqrt(s) = 8 TeV with the CMS Experiment / Frank Roscher. Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1079594949/34.

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Swedish, Stephen. "Searches for new resonances decaying to top-antitop quark pairs with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50169.

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This work presents the results of two analyses searching for massive resonances decaying to top-antitop quark pairs in sqrt(s) = 7 TeV proton-proton collisions measured with the ATLAS detector at the CERN Large Hadron Collider. The peculiar position of the top-quark within the Standard Model, as the most massive particle, motivates many theories predicting the existence of new massive particles that couple strongly to top-quarks. These particles may manifest themselves at the LHC as new massive resonances decaying to top-antitop quark pairs. An analysis conducted on the first 2.04/fb^-¹ of data collected in 2011 searched for resonances in the subset of top-pair events where the W-bosons from each top decay decayed leptonically to a final state electron or muon. A second analysis conducted on the full 4.7/fb^-¹ of 2011 data searched for resonances in the subset of top-quark pair events where W-bosons from each top decay decayed hadronically to a diquark pair. The analysis focused on the case were each top-quark is sufficiently boosted such that the resultant fully hadronic system is highly collimated, and reconstructable as a single hadronic jet with large angular separation. In each analysis, the leptophobic Z' from topcolor assisted technicolor models, and the KK-gluon from Randall-Sundrum warped extra-dimension models were chosen as benchmarks to test for the presence of narrow and wide resonances respectively. No significant deviation from the Standard Model was observed in either analysis. The results were used to set 95% C.L. upper limits on the cross-section times branching ratio to top-quark pairs as a function of resonance mass for each benchmark model. The existence of a Randall-Sundrum KK-gluon was excluded at the 95% C.L. over the mass range 500 to 1620 GeV.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

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Zhang, Rui [Verfasser]. "Inclusive and differential cross-section measurements of tW single top-quark production at √s = 13 TeV with the ATLAS detector / Rui Zhang." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1191832031/34.

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Arndt, Till [Verfasser], and Andreas [Akademischer Betreuer] Meyer. "Precision measurement of the top quark pair production cross sectionat √s = 13 TeV with the CMS detector / Till Arndt ; Betreuer: Andreas Meyer." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1202113141/34.

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Müller, Denise [Verfasser], and T. [Akademischer Betreuer] Müller. "Search for single top quark production in the s channel at 13 TeV with the CMS experiment / Denise Müller ; Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1214301541/34.

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Teixeira, Dias Castanheira Matilde. "Measurement of the single top t-channel cross section using a cut based analysis with the ATLAS detector in pp collisions at √s = 7 TeV." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/9083.

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This thesis presents studies of the single top t-channel in the electron plus jets mode. In order to understand this channel, an account of the present theoretical models is given. This work relies on collisions data from the ATLAS detector and its components are presented here. A summary of the work involving the SCT, part of the tracking system in ATLAS, is also explained here. Studies were performed to optimize the measurement of the Lorentz Angle of the holes in the Silicon for the initial data taking period. The data studied was acquired by ATLAS during 2011, with a total integrated luminosity of 4.7 pb−1 at a √s = 7 TeV. Monte Carlo simulation of signal and background events was also used throughout. Background studies were performed to correctly determine the expected amount of QCD via the Jet Electron data-driven method and of light or heavy flavour jets produced in association with a W boson, which is one of the dominant backgrounds for the t-channel. A cut based analysis was then applied to the data and simulation in order to better discriminate the t-channel signal. A binned likelihood fit to the invariant mass of the reconstructed top quark was performed and the cross section value for the t-channel process was calculated: σt−channel = 62.2±8.0(stat)+8.6 −8.8(syst) pb which is in good agreement with the theoretically predicted value. Finally, the response (preco T /ptrue T ) of light quark or gluon initiated jets is evaluated for both the t-channel and the Wt associated production, in order to determine the flavour composition uncertainty, as part of the framework that provides the jet energy scale uncertainties in a multiple jets environment. Other sources of system- atics are also reviewed.

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Bender, Michael [Verfasser], and Otmar [Akademischer Betreuer] Biebel. "Measurement of the top quark mass using lepton transverse momenta with the ATLAS detector at √s = 8 TeV / Michael Bender ; Betreuer: Otmar Biebel." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/112910527X/34.

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Thusini, Xolisile. "Characterising the sources of fake leptons from top quarks in same sign W boson scattering with the ATLAS detector at √s = 13 TeV." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/28995.

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Esch, Hendrik [Verfasser], Reiner [Akademischer Betreuer] Klingenberg, and Wolfgang [Gutachter] Wagner. "Measurement of the top quark mass in topologies enhanced with single top quarks produced in the t-channel using flavour tagging and a neural network with ATLAS data at √s = 8TeV / Hendrik Esch. Betreuer: Reiner Klingenberg. Gutachter: Wolfgang Wagner." Dortmund : Universitätsbibliothek Dortmund, 2015. http://d-nb.info/1101476516/34.

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Becker, Anne Kathrin [Verfasser]. "Inclusive and Differential Cross-Section Measurements of t-Channel Single Top-Quark Production at √s = 7 TeV with the Atlas Detector / Anne Kathrin Becker." Wuppertal : Universitätsbibliothek Wuppertal, 2015. http://d-nb.info/1071413570/34.

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Cioară, Irina Antonela [Verfasser]. "Associated Production of a Top Quark and a Z Boson in pp Collisions at √s=13 TeV Using the ATLAS Detector / Irina Antonela Cioară." Bonn : Universitäts- und Landesbibliothek Bonn, 2018. http://d-nb.info/1170778038/34.

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Tepel, Phillipp [Verfasser]. "Measurement of the Fiducial and Total Single Top-Quark t-Channel Production Cross-Sections with the ATLAS Detector at √s = 8 TeV / Phillipp Tepel." Wuppertal : Universitätsbibliothek Wuppertal, 2018. http://d-nb.info/1164103164/34.

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Greder, Sébastien. "Etiquetage des quarks beaux et mesure de la section efficace de production de paires de quarks top à √s=1,96 TeV dans l'expérience DØ." Université Louis Pasteur (Strasbourg) (1971-2008), 2004. http://www.theses.fr/2004STR13194.

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Le travail présenté dans ce mémoire concerne la mesure de la section efficace de production de paires de quarks top dans le canal lepton + jets (électron et muon). Les données analysées ont été collectées par le détecteur DØ entre 2001 et 2004 à une énergie au centre de masse de 1. 96 TeV auprès du collisionneur proton-antiproton Tevatron situé au FERMILAB. Elles correspondent à une luminosité intégrée de 160 pb-1 par canal. Chaque quark top se désintègre en produisant un boson W et un quark beau. La première partie de ce travail de thèse a été consacrée à l'élaboration d'un algorithme d'identification des jets de quarks beaux, JLIP. Cet algorithme repose sur l'utilisation du paramètre d'impact des traces et permet d'assigner à un jet une probabilité de provenir du point d'interaction primaire. L'efficacité d'iden -tification de cet algorithme est de 45% pour des paires top-antitop pour un bruit de fond rejeté de 99. 7%. La deuxième partie du travail concerne la présélection permettant d'isoler des événements compatibles avec une topologie de type W+jets. Les bruits de fond multijets et W+jets sont évalués dans les données réelles et la simulation. La section efficace de production de paires de quarks top est mesurée à partir des candidats de plus de 3 jets dont l'un, au moins, est identifié par l'algorithme JLIP. Les sources d'incertitudes systématiques ont été étudiées en détail. Le résultat a été comparé aux calculs théoriques et aux autres mesures effectuées dans les expériences DØ et CDF
The work presented in this thesis concerns the measurement of the top-antitop production cross-section in the lepton + jets channel (electron and muon). The analysed data have been collected with the DØ detector between 2001 and 2004 at a center-of-mass energy of 1. 96 TeV, at the Tevatron proton-antiproton collider located at FERMILAB. These data correpond to an integrated luminosity of 160 pb-1 in each channel. Each top quark decays into a W boson and a b quark. The first part of this work has been focused on the elaboration of an algorithm, JLIP, aimed at identifying jets arising from b quarks decay products. This algorithm uses the impact parameter of the tracks to assign a jet a probability that it originates from the primary interaction point. Its efficiency for top-antitop events is about 45% with a rejected background of 99. 7%. The second part of this work deals with the preselection step that allows isolating events which are likely to be compatible with a W+jets toplogy. Multijets and W+jets backgrounds are estimated from real data and simulation. The top pair production cross-section is extracted from candidate events that have at least three jets, one among them being tagged by the JLIP algorithm. Sources of systematics uncertainties have been studied in detail. Results have been compared with the theoritical expectations and with other measurements performed in the DØ and CDF experiments

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Symonds, Philip. "Top pair production cross sections and differential cross sections in the semi-leptonic channel using the CMS detector at √s = 7 and 8 TeV." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/10917.

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The top quark has been extensively studied since the Large Hadron Collider (LHC) began operating in 2010. The excellent performance of both the LHC and the Compact Muon Solenoid (CMS) detector has enabled complex analyses of many properties of the top quark. In this thesis inclusive and differential top pair (tt) production cross sections have been measured. Inclusive tt cross sections of 145.6 ± 8.2 (stat.) +38.1/28.3 (syst.) pb and 237.4 ± 1.9 (stat.) +20.4/-16.9 (syst.) pb were measured at 7 TeV and 8 TeV center-of-mass collision energies using luminosities of 1 fb⁻¹ and 19.7 fb⁻¹, respectively. These measurements were performed in the semi-leptonic channel by means of a maximum likelihood t of the lepton's pseudorapidity. The work in this thesis focuses specifically on the muon-plus-jets channel. The methods used for measuring the inclusive cross sections were built upon to measure differential cross sections with respect to event level observables. These observables include the missing transverse energy (Emiss T ) as well as some other kinematic distributions involving the jets, lepton and Emiss T in the decay. These results are unfolded to remove detector and selection effects and have uncertainties in the range of 3% to 15%. A low uncertainty is achieved by normalising the differential cross section using the total cross section. This leads to cancellations of some uncertainties. The results were compared with different Monte Carlo generators and with different input parameters. No significant deviations from predictions of the Standard Model were observed. This thesis also contains test beam results on CMS ECAL Endcap Lead Tungstate (PbWO4) crystals. These crystals had been damaged using various doses of proton irradiation. The damage for some crystals is expected to be roughly equivalent to 300 fb-1 of integrated luminosity at √s = 14 TeV. The energy resolution for these crystals was seen to reduce by close to a factor of 20.

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Searcy, Jacob. "Measurement of the Top Quark Pair Production Cross Section in p-p Collisions at √s = 7 TeV in the l + τ Channel with ATLAS." Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/12944.

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The measurement of the cross section of top quark pair production in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb-1 . Events with an isolated electron or muon and a tau lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b-quark. The measured cross section, σtt̄ = 178 ± 12 stat. ± 18 sys. ± 7 lumi. pb, is in good agreement with the Standard Model prediction.

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Atlay, Naim Bora [Verfasser]. "Differentiating top-quark - photon coupling: inclusive and differential cross-section measurements of top-quark pair production in association with a photon in the single lepton channel in pp collisions data at √s 8TeV with the ATLAS experiment / Naim Bora Atlay." Siegen : Universitätsbibliothek der Universität Siegen, 2018. http://d-nb.info/1163453919/34.

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Greder, Sébastien. "Etiquetage des quarks beaux et mesure de la section efficace de production de paires de quarks top à $\sqrt(s)$ = 1,96 TeV dans l'expérience D0." Phd thesis, Université Louis Pasteur - Strasbourg I, 2004. http://tel.archives-ouvertes.fr/tel-00009071.

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Le travail présenté dans ce mémoire concerne la mesure de la section efficace de production de paires de quarks top dans le canal lepton + jets (électron et muon). Les
données analysées ont été collectées par le détecteur DØ entre 2001 et 2004 à une énergie au
centre de masse de 1.96 TeV auprès du collisionneur proton-antiproton Tevatron situé au
FERMILAB. Elles correspondent à une luminosité intégrée de 160 pb-1 par canal.
Chaque quark top se désintègre en produisant un boson W et un quark beau. La première
partie de ce travail de th èse a été consacrée à l'élaboration d'un algorithme d'identification des
jets de quark s beaux, +-*1. Cet algorithme repose sur l'utilisation du paramètre d'impact des
traces et permet d'assigner à un jet une probabilité de provenir du point d'interaction primaire.
L'efficacité d'identification de cet algorithme est de 45% pour des paires top-antitop pour un bruit de fond rejeté de 99.7%.
La deuxième partie du travail concerne la présélection permettant d'isoler des événements compatibles avec une topologie de type W+jets. Les bruits de fond multijets et W+jets sont évalués dans les données réelles et la simulation. La section efficace de production de paires de quarks top est mesurée à partir des candidats de plus de 3 jets dont l'un, au moins, est
identifié par l'algorith me +-*1. Les sources d'incertitudes systématiques ont été étudiées en
détail. Le résultat a été comparé aux calculs théoriques et aux autres mesures effectuées dans
les expériences DØ et CDF.

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Renz, Manuel [Verfasser], and Thomas [Akademischer Betreuer] Müller. "Erste Messung des Wirkungsquerschnitts der Top-Quark-Paarproduktion bei √s=7 TeV im Elektron+Jets Kanal mit dem CMS-Experiment / Manuel Renz. Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2011. http://d-nb.info/1014279658/34.

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Rieck, Patrick [Verfasser], Thomas [Gutachter] Lohse, Heiko [Gutachter] Lacker, and Ulrich [Gutachter] Husemann. "Measurement of s-channel single top-quark production with the ATLAS detector using total event likelihoods / Patrick Rieck ; Gutachter: Thomas Lohse, Heiko Lacker, Ulrich Husemann." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://d-nb.info/1117081303/34.

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Poll, Andrew James. "Measurement of the top-quark pair production cross section with soft muon b-tagging in pp collisions at √s = 7 TeV with the Atlas detector." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2446.

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This thesis presents a study of the measurement of the top pair production cross section in the semileptonic decay channel with soft muon b-tagging at the Atlas detector using early LHC data. A theoretical overview of current research in particle physics, motivating the construction of the LHC and the Atlas detector is discussed followed by the main motivations behind a measurement of the top cross section. A summary of my work undertaken for the semiconductor tracker (SCT) collaboration on Atlas, including shift work and the refurbishment of the SR1 barrel sector and spare endcap disk is detailed. Following this the electron isolation in top and Z boson events was examined with Monte Carlo simulated events to optimise the selection criteria for electrons from W boson decay in top events. As part of the top cross section measurement, the e ciency and scale factor, compared to Monte Carlo studies, of using a 2 match cut on soft muons was calculated using the decay of the J= in early LHC data. The last chapter details the development of an analysis framework and measurement of the top pair production in the semileptonic decay channel with soft muon b-tagging. This measurement builds on the work in the previous chapters utilising both the electron isolation requirement from Monte Carlo simulations and the scale factor on the soft muon 2 match cut for b-tagging to yield a measurement of the top cross section in 2.9 pb 1 of LHC data.

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Abazov, V. M., B. Abbott, B. S. Acharya, M. Adams, T. Adams, J. P. Agnew, G. D. Alexeev, et al. "Measurement of the inclusive t ¯ t production cross section in p ¯ p collisions at √ s = 1.96 TeV and determination of the top quark pole mass." AMER PHYSICAL SOC, 2016. http://hdl.handle.net/10150/622486.

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The inclusive cross section of top quark-antiquark pairs produced in p (p) over bar collisions at root s = 1.96 TeV is measured in the lepton + jets and dilepton decay channels. The data sample corresponds to 9.7 fb(-1) of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of sigma(t<(t)over bar) = 7.26 +/- 0.13(stat)(-0.50)(+0.57) (syst) pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is m(t) = 172.8 +/- 1.1(theo)(-3.1)(+3.3) (exp) GeV.

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Dissertations / Theses on the topic 'S-TOP'

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