Le sujet principal de cette thèse porte sur la recherche d’un boson de Higgs additionnel de plus haute masse à travers sa désintégration en une paire de bosons de jauge Z (H → ZZ(*)) en utilisant les données enregistrées avec l’expérience ATLAS auprès du Grand Collisionneur de Hadrons (LHC). Quatre analyses distinctes sont présentées en fonction du mode de désintégration du boson Z soit une paire de leptons chargés (électrons ou muons), soit une paire de neutrinos soit une paire de quarks ; ces analyses sont appelés ZZ → 4l, 2l2ν, 2l2q et 2ν2q. L’étude utilise 20.3 fb⁻¹ de données de collisions proton-proton enregistrées au cours de la première phase du LHC (Run-1) à une énergie dans le centre de masse de 8 TeV. La stratégie de recherche segmente les données en supposant que les mécanismes de production de bosons de Higgs additionnel sont les mêmes que dans le Modèle Standard (SM), et modélise le signal avec une largeur qui est faible par rapport à la résolution de la masse invariante. La région de masse du boson de Higgs considéré s’étend de 140 GeV jusqu’à 1 TeV. Aucun nouveau boson de Higgs n’a été trouvé. La combinaison de résultats de quatre modes de désintégration donne des limites supérieures sur la section efficace σ de ce boson de Higgs additionnel (σ × H → ZZ(*)) qui s’étend de 359 fb à mH = 200 GeV à 11 fb à mH = 1TeV. Les résultats sont également interprétés dans le contexte des modèles au-delà du SM, à savoir les modèles à deux doublets. L’analyse H → ZZ(*) → 4l est également réalisée au cours de la deuxième phase du LHC (Run-2) en utilisant 3.2 fb⁻¹ de données de collisions de proton-proton enregistrées en 2015 à une énergie à une énergie dans le centre de masse de 13 TeV. Aucun excès significatif d’évènements sur la prédiction du MS n’est trouvé. Les limites supérieures sur la section efficace (σ × H → ZZ(*) → 4l) sont de 4.5 fb à mH = 200 GeV et 1 fb à mH = 1 TeV. La dernière partie de la thèse porte sur la caractérisation des détecteurs à scintillation d’ATLAS pour le déclenchement d’un biais minimal dans la région avant (le Minimum Bias Trigger Scintillators (MBTS)) en utilisant les rayons cosmiques. En raison de la dégradation des matériaux provoquée par des dommages dus à l’irradiation dans la première phase de fonctionnement du LHC, les MBTS devaient être remplacés lors de l’arrêt du LHC qui a eu lieu en 2014. Avant leur installation dans ATLAS, ces détecteurs ont été caractérisés en laboratoire en utilisant les rayons cosmiques. / The main subject of this thesis is the search for an additional heavy Higgs boson through its decay into a pair of Z bosons (H → ZZ(*)) using data recorded with the ATLAS experiment installed at the Large Hadron Collider (LHC). Four distinct analyses are presented, which are distinguished by the decay mode of the Z boson into either a pair of charged leptons (electrons or muons), into a pair of neutrinos or into a pair of quarks, denoted according to final-state, i.e. as 4l, 2l2ν, 2l2q and 2ν2q. The study is performed using 20.3 fb⁻¹ of proton-proton collision data recorded during the first phase of LHC operation (Run-1) at centre-of-mass energy of √s = 8 TeV. A search strategy is employed which segments the data according to the Higgs boson production mechanism, assuming that these are the same as in the Standard Model (SM). Furthermore, the signal is modelled with a width that is small compared to the experimental mass resolution. The Higgs boson mass range considered extends up to 1 TeV for all four decay modes and down to as low as 140 GeV, depending on the decay mode. No significant excess of events over the Standard Model prediction is found. A simultaneous fit to the four decay modes yields upper limits on the heavy Higgs boson production cross-section times H → ZZ branching ratio ranging from 359 fb at mH = 200 GeV to 11 fb at mH = 1 TeV for the gluon-fusion production mechanism, and from 214 fb at mH = 200 GeV to 13 fb at mH = 1 TeV for the vector-boson fusion production mechanism. The results from these four searches are also interpreted in the context of models beyond the SM, namely the Type-1 and Type-2 2 Higgs Doublet Model. The heavy Higgs boson search is also performed with the H → ZZ(*) → 4l decay mode alone using 3.2 fb⁻¹ of proton-proton collision data recorded during the second phase of LHC operation (Run-2) at an increased centre-of- mass energy of √s = 13 TeV. No significant excess of events over the Standard Model prediction is found. Upper limits are set on the heavy Higgs boson production cross-section times H → ZZ(*) → 4l branching ratio of 4.5 fb at mH = 200 GeV and 1 fb at mH = 1 TeV. Lastly, a project of a more technical character is presented. In this study, the scintillation detectors employed by ATLAS for triggering with minimal bias in the forward region, the Minimum Bias Trigger Scintillators (MBTS), are characterised. Due to material degradation caused by radiation damage in the early phases of LHC operation, the MBTS had to be replaced during the LHC shutdown taking place in 2014. Before installation in ATLAS, these detectors were characterised in appropriate laboratory facilities using cosmic radiation.

The Standard Model (SM) of particle physics is widely taken as an elegant effective theory of nature at the electroweak scale, with new physics expected at higher energy. Collider searches and other experimental inputs play a vital role in our hunt for the unknown physics, offering great insights along the way and eventually establishing the extension to the SM. Here we present our studies on prospects of direct and indirect searches for three types of models beyond the SM. The Inert Doublet Model (IDM) extends the SM electroweak sector by an extra Higgs doublet with a Z₂-symmetry. We first examine the IDM dilepton signal at the LHC with a center-of-mass energy of 14 TeV and find it exceeding SM backgrounds at 3σ–12σ significance level, with 100 fb⁻¹ integrated luminosity. We further show that it is possible to obtain the IDM trilepton signal at the 5σ significance level, with an integrated luminosity of 300 fb⁻¹. The Left-Right Twin Higgs (LRTH) model solves the little Hierarchy problem by taking the SM Higgs as a pseudo-Goldstone boson from the spontaneous breaking of a global symmetry. We focus on the discovery potential of the heavy top quark partner in the LRTH model at the LHC. With a luminosity of 30 fb⁻¹ at the early stage of the LHC operation, we conclude that the heavy top partner could be observed at a significance level above 5σ. Supersymmetric extensions of the SM enable cancellations among loop corrections to the Higgs mass from bosonic and fermionic degrees of freedom, leading to a solution to the well-known Hierarchy problem. However, the supersymmetry has to be broken by certain mechanism. We present an exploration of the B-physics observables and electroweak precision data in three distinct soft supersymmetry-breaking scenarios. Projection for future sensitivities of the precision data is also explored.

Many theories of physics beyond the Standard Model predict the existence of TeV-scale resonances that decay to top quark pairs. This thesis presents a search for such resonances produced in proton-proton collisions at a centre-of-mass energy of 7 TeV at the CERN Large Hadron Collider with 4.7 fb−1 of data collected by the ATLAS detector in 2011. The search is performed in the channel where both top quarks decay hadronically and emerge in highly boosted states, and the collimated decay products of each boosted top quark are reconstructed as a single large jet (a “top quark jet”). A tagging technique based on the distinctive masses and substructures of these top quark jets is used to distinguish them from light quark and gluon jets. The data are found to be consistent with Standard Model predictions, and 95% credibility level upper limits are set on the cross section times branching ratio for leptophobic Z' bosons in a Topcolour model and Kaluza-Klein gluons as predicted by the bulk Randall-Sundrum model. These limits exclude Kaluza-Klein gluons with masses between 1.02 TeV and 1.62 TeV. The substructure of light quark and gluon jets, which form the dominant background to hadronically decaying boosted top quarks, is studied in an auxiliary measurement using 35 pb−1 of data collected by ATLAS during the 2010 run period. The observed substructure of these jets are found to be in good agreement with theoretical predictions.

Many theories of physics beyond the Standard Model predict the existence of TeV-scale resonances that decay to top quark pairs. This thesis presents a search for such resonances produced in proton-proton collisions at a centre-of-mass energy of 7 TeV at the CERN Large Hadron Collider with 4.7 fb−1 of data collected by the ATLAS detector in 2011. The search is performed in the channel where both top quarks decay hadronically and emerge in highly boosted states, and the collimated decay products of each boosted top quark are reconstructed as a single large jet (a “top quark jet”). A tagging technique based on the distinctive masses and substructures of these top quark jets is used to distinguish them from light quark and gluon jets. The data are found to be consistent with Standard Model predictions, and 95% credibility level upper limits are set on the cross section times branching ratio for leptophobic Z' bosons in a Topcolour model and Kaluza-Klein gluons as predicted by the bulk Randall-Sundrum model. These limits exclude Kaluza-Klein gluons with masses between 1.02 TeV and 1.62 TeV. The substructure of light quark and gluon jets, which form the dominant background to hadronically decaying boosted top quarks, is studied in an auxiliary measurement using 35 pb−1 of data collected by ATLAS during the 2010 run period. The observed substructure of these jets are found to be in good agreement with theoretical predictions.

In this master thesis we have examined the possibility of pricing multiple American options, on an underlying asset with discrete dividends, with a finite difference method. We have found a good and stable way to price one American option by solving the BSM PDE backwards, while also calculating the Greeks of the option with automatic differentiation. The list of Greeks for an option is quite extensive since we have been using a local volatility surface. We have also tried to find a way to price several American options simultaneously by solving a forward PDE. Unfortunately, we haven't found any previous work that we could use with our local volatility surface, while still keeping down the computational time. The closest we got was to calculate the value of a compound option in a forward mode, but in order to use this to value an American option, we needed to go through an iterative process which calculated a forward or backward European PDE in every step.

Dissertação (mestrado)—Universidade de Brasília, Faculdade UnB Planaltina, Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento Rural, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-12-09T13:02:09Z No. of bitstreams: 1 2016_LucianaVieiradeNovaisRodrigues.pdf: 1783483 bytes, checksum: 812f7f95b620f6dc25d1043885ca25c8 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2017-01-05T18:40:00Z (GMT) No. of bitstreams: 1 2016_LucianaVieiradeNovaisRodrigues.pdf: 1783483 bytes, checksum: 812f7f95b620f6dc25d1043885ca25c8 (MD5) / Made available in DSpace on 2017-01-05T18:40:00Z (GMT). No. of bitstreams: 1 2016_LucianaVieiradeNovaisRodrigues.pdf: 1783483 bytes, checksum: 812f7f95b620f6dc25d1043885ca25c8 (MD5) / As políticas públicas são ferramentas utilizadas para viabilizar mudanças na sociedade. Elas podem atuar e transformar diferentes grupos sociais trazendo novas perspectivas de desenvolvimento para a população beneficiada. Para tanto, é necessário delinear e planejar o processo de implementação, desenvolvimento e monitoramento da política, de forma a controlar e intervir nos possíveis problemas que ocorram no seu percurso. O presente trabalho discute a política pública que criou o Plano Brasil sem Miséria (BSM), que envolve vários ministérios e diversas políticas conjugadas, as quais resultam em um conjunto de ações integradas para elevação de renda de pessoas que vivem em uma faixa de extrema pobreza. A Inclusão Produtiva faz parte dessa política, que compreende a Assistência Técnica e Extensão Rural (ATER) e o Fomento. Tais programas estão altamente vinculados no objetivo de geração de renda para populações rurais. A ATER pública busca um direcionamento pedagógico libertário, participativo e interativo, o que permitiria o desenvolvimento de um projeto produtivo nos parâmetros do que busca o BSM, qual seja, o de permitir que uma população extremamente pobre no meio rural eleve o seu desenvolvimento reduzindo o grau de pobreza e alçando outros benefícios, além do aumento da renda. O Fomento, possibilitado pela Inclusão Produtiva, permite o custeio de um pequeno projeto para a produção orientada pela ATER, sendo fonte de renda das famílias atendidas. Os pescadores artesanais, que ocupam o Território do Sertão do São Francisco, estão inseridos no grupo da população que vive nas condições de extrema pobreza. Desenvolvem suas atividades de forma artesanal, vivem na zona rural e possuem características culturais e tradicionais próprias. Do ponto de vista metodológico, optou-se pela análise de atuação conduzida pela a ATER na perspectiva de prospectar os resultados advindos dessas ações para a melhoria do nível de vida do grupo de pescadores. Considera-se não apenas a avaliação da renda, mas, também, quais desdobramentos podem ocorrer para tornar suas atividades mais estáveis e sustentáveis no futuro. A avaliação evidenciou que a atividade de ATER está atingindo seus objetivos relacionados à elevação de renda no âmbito do Plano Brasil sem Miséria e que está ocorrendo a integração de políticas no meio rural para pescadores artesanais, melhorando a geração de renda a partir da possibilidade de projetos que ofereçam um financiamento. No que se refere à pesquisa de campo, desenvolvida em meio aos pescadores artesanais do Território da cidadania do Sertão do São Francisco, foi possível obter informações relacionadas ao processo de inserção na política viabilizada pelo Plano Brasil sem Miséria, em especial aquela conduzida pela Chamada 14/2010. Também foi possível averiguar os primeiros indícios da efetividade desta ação na vida dos beneficiários da Chamada. _________________________________________________________________________________________________ ABSTRACT / Public policies are tools used to enable changes in society. They can act and transform different social groups bringing new development perspectives for the beneficiary population. Therefore, it is necessary to outline and plan the implementation process, development and monitoring of policy, in order to control and intervene in possible problems that occur along the way. This paper discusses the public policy that created the “Brazil without Poverty Plan” (BSM), involving several government departments and combined policies which result in a set of integrated actions to increase income of people living in extreme poverty. The “Productive Inclusiveness” is part of that policy, including the “Technical Assistance and Rural Extension” (ATER) and “Resources to invest” (Foment). Such programs are highly linked in order to increase income of rural populations. ATER searches a libertarian pedagogical direction, participatory and interactive, allowing the development of a productive project based on BSM parameters, which is to allow the extremely poor population in rural areas to achieve development able to reduce the level of poverty and raise other benefits to increase income. “The Resources to invest” (Foment), made possible by the “Productive Inclusiveness”, allows the cost of a small project driven by ATER, becoming source of funds of the beneficiaries families. Artisanal fishermen who occupy the strip “Sertão of São Francisco” are groups living in extreme poverty. They develop their craft activities, live in rural areas and have they own cultural and traditional characteristics. From a methodological point of view, we opted for the analysis of activities conducted by ATER, seeking the results of this action in improving fishermen's living conditions. It is considered not only the assessment of income, but also, what developments may occur to make their activities more stable and sustainable in the future. The evaluation showed that the ATER activity is meeting its objectives related to the increase of income within the scope of Brazil without Poverty Plan, and it´s running the integration of policies in rural areas for artisanal fishermen, improving the income generation from the possibility of projects that provide funding. Considering the field research conducted among the artisanal fishermen, located in the “Territories of Citizenship/ Sertão of São Francisco”, it was possible to obtain information related to the insertion process enabled by the Brazil without Poverty Plan, especially that conducted by “Call 14/2010” .It was also possible to find out earliest evidence, concerning the effectiveness of “Call 14/2010”in the lives of its beneficiaries.

No description available.

This thesis describes a series of studies related to searches for new phenomena, beyond the Standard Model of particle physics, in high energy hadron collisions. In such searches, it becomes crucial to identify the Standard Model backgrounds in order to resolve a potential new signal. The thesis presents a method that uses photon events to determine one of such backgrounds, caused by the production of Z boson events. The studies performed to validate the method, both theoretically and experimentally, are presented and the method was shown to be successful as well as to provide reliable results. Theoretically, the method is found to be robust up to a ~10% uncertainty. Experimentally, the method is implemented to estimate the Z(vv) + jets background for the SUSY 0l + E_T^miss + jets search in the ATLAS experiment at the Large Hadron Collider, where this background is one of the most important components for the final sensitivity and is impossible to measure directly. The main experimental results presented are the latest from ATLAS at the time of writing, corresponding to the full dataset of proton-proton collisions delivered by the LHC in 2011 (4.7 fb^-1) at a centre of mass energy of 7 TeV. Given that this method has been mainstream since 2010, brief comparisons to the results from previous analyses that used smaller datasets with the same centre of mass energy are also given, as well as additional cross-checks that support the robustness and validity of the method. The results presented here have contributed to the determination of the world's best limits with respect to SUSY models, which currently exclude equal mass squarks and gluinos below 1.4 TeV.

This thesis presents a search for the supersymmetric partner of the top quark in the final state with one lepton. The search focuses especially in the region of the parameter space where the 2-body decay dominates. The analysis is performed using LHC full Run 2 data at √s = 13 TeV as recorded by the ATLAS detector. No significant excess above the backgrounds is observed, and 95% confidence level exclusion limits are calculated in the stop-neutralino mass plane. Stops are excluded up to 1200 GeV in the low neutralino mass scenario of below 400 GeV. The Tile Calorimeter is part of the ATLAS calorimeter system whose main task is to measure the energy of hadrons. A performance study is conducted on the Tile Calorimeter using muons from W boson decay originating from proton-proton collisions. Each calorimeter cell response is measure in data and compared with detector simulation.  The azimuthal cell response uniformity is also investigated using a likelihood method. Overall, a good data to detector simulation agreement and azimuthal uniformity is observed which shows well-calibrated cells and uniform responses among the calorimeter modules.

No description available.