Après une description du LHC, de l'expérience Atlas et des systèmes calorimétriques à argon liquide, cette thèse montrera une étude qui vise à valider la simulation des gerbes électromagnétiques en utilisant des muons cosmiques. Nous discuterons ensuite de la reconstruction des pions neutres et de la cartographie de la matière dans le trajectographe interne en utilisant des photons convertis avec les premières données. Pour finir, nous présenterons les résultats obtenus concernant la recherche du boson de Higgs dans le canal H->ZZ->4l avec les données 2011 et une énergie √s=7TeV dans le centre de masse. / After a description of the LHC, the ATLAS experiment and the liquid argon calorimeter system, this thesis will show a study to validate the simulation of electromagnetic showers using cosmic muons. Then, we will discuss about neutral pion reconstruction and about the material mapping of the inner tracker using converted photons with the first data. Finally, we will present the results concerning the search for the Higgs boson in the H-> ZZ-> 4l channel with the 2011 data and a energy √s = 7TeV.

Cette thèse décrit la recherche de nouvelles particules scalaires octets de couleur dans les données de l'expérience ATLAS auprès du Grand Collisionneur de Hadrons (LHC). Pour une large gamme de masse, la désintégration de ces scalaires en deux partons du MS domine. Cela motive la recherche de ces nouveaux scalaires dans des états finaux multijet, où ils se signaleraient comme des résonances dijet. Comme les nouveaux scalaires sont produits par paires, un état final contenant au moins quatre jets est utilisé comme environnement de recherche. Une méthode est développée pour extraire une possible résonance multijet scalaire du grand fond QCD et est utilisée pour chercher de tels scalaires dans les données de l'expérience ATLAS collectées en 2010 et 2011. Les données sont en accord avec l'estimation du fond et des limites sont posées sur la section efficace de production des scalaires en fonction de leur masse. En interprétant ces limites dans des modèles de supersymétrie, le gluon scalaire du MRSSM et du modèle hybride N=1/N=2 est exclu à 95 % CL entre 100 et 287 GeV. Les limites sont aussi interprétées dans un modèle de symétrie de jauge à la QCD, où le sgluon est remplacé par l'hyperpion qui est exclu dans une gamme de masse légèrement plus restreinte de part sa section efficace plus faible. / This thesis describes the search for new color-octet scalar particles in the ATLAS experiment data at the Large Hadron Collider (LHC). For a wide range of mass, the decay of the scalar to two SM partons dominates. This motivates the search for these new scalars in multijet final states, where they would manifest as dijet resonances. As the new scalars are products in pairs, a final state containing at least four jets is used as a search environment. A method is developed to extract a possible scalar resonance from the multijet QCD background and is used to search for such scalar in the data from the ATLAS experiment collected in 2010 and 2011. The data are in agreement with the estimation of the background and limits are set on the scalar production cross section as a function of the scalar mass. Interpreting these limits in models of supersymmetry, the scalar gluon of the MRSSM and of the hybrid N=1/N=2 model is excluded at the 95 % CL between 100 and 287 GeV. Limits are also interpreted in a model of gauge symmetry à la QCD, where the sgluon is replaced by the hyperpion excluded in a mass range slightly smaller because of its smaller cross section.

ALFA (Absolute Luminosity for ATLAS) vise à mesurer la luminosité absolue pour l'expérience ATLAS avec une incertitude de 2 - 3\% et la section efficace totale. La luminosité est reliée au nombre d’événements. Plus la luminosité est élevée, plus le nombre d’événements est élevé. C'est donc une quantité importante pour les collisionneurs en général et notamment pour le LHC (Large Hadron Collider). LHC est constitué de deux faisceaux circulant dans deux chambres à vide différentes et collisionnant aux quatre points d'interaction où les principales expériences de physique sont positionnées (ATLAS, CMS, ALICE et LHCb). Les détecteurs constituant ALFA insérés dans des Pots Romains sont positionnés à 240 m de distance du point d'intéraction d'ATLAS après six quadrîpoles et deux dipôles qui constituent la partie de ligne faisceau utile à ALFA et localisée sur le LHC.Les détecteurs sont constitués de fibres scintillantes pour détecter les protons élastiques issus du Point d'Interaction. Ces protons sont transportés au travers des différents aimants qui constituent la ligne de faisceau considérée et qui nécessite une optimisation des paramètres optiques pour les besoins de la mesure. Nous appellerons les optiques fort β, les optiques utilisées durant les périodes expérimentales dédiées à ALFA. Les paramètres des optiques fort β ont été simulés afin de remplir le cahier des charges demandé pour ALFA et elles ont été testées sur le LHC en 2011 et 2012 pendant un certain nombre de périodes expérimentales spécifiques aux optiques fort β sur le LHC.Ces périodes expérimentales se sont terminées en 2013 avant l'arrêt du LHC. Les paramètres optiques ont été mesurés et comparés aux simulations.Certains paramètres ayant des valeurs bien meilleures que celles attendues. Cela a aussi permis de regardes quelques incertitudes sur les paramètres optiques et d'évaluer l'impact de certains de ces paramètres sur la mesure de section efficace totale. / ALFA (Absolute Luminosity For ATLAS) aims at measuring the absolute luminosity for the ATLAS experiment with an incertitude down to 2-3 \% and the total elastic cross section. The luminosity is related to the number of events, the highest the luminosity, the highest the number of events. This is, then, an important quantity for colliders like LHC (Large Hadron Collider). LHC is made of two beams circulating in two different beam pipes and colliding at four interaction points where the four physics experiments are located (ATLAS, CMS, ALICE, LHCb). ALFA detectors inserted into Roman Pots (RPs), have been placed around ATLAS at 240 m distance from the collision point (IP1) after six quadrupoles magnets and two dipoles defining the ALFA beam line which is part of the LHC ring.The detectors are made of scintillating optics fibers to catch elastic protons generated at IP1. These protons are tracked through the LHC magnets beam line which needs to be optimized in terms of optics parameters. We call high β optics, the optics used for special ALFA runs measurements. The high β optics parameters have been simulated to fulfill the ALFA requirements and have been tested on LHC in 2011 and 2012 during a certain number of LHC special runs. It has ended at the end of 2013. The parameters have been measured and compared with simulations. Some of them achieving a better value than expected. It allowed us to calculate systematic uncertainties and to evaluate the impact of some optics parameters on the total elastic cross section measurement.

De nombreuses recherches ont été consacrées aux signatures des modèles supersymétrique depuis le Run1 du LHC qui a fourni des données à 7 et 8 TeV. Parmi ceux-ci, la recherche du chargino-neutralino (C1, N2) dans les états finals avec 1 lepton, 2 b-jets compatibles avec un boson de Higgs et une énergie transverse manquante. L'analyse des données collectées par ATLAS à 8 TeV en 2012 a permis d'exclure à 95% C.L. les modèles simplifiés pour lesquels le neutralino le plus léger (N1) est non massif et les C1, N2 sont de moins de 250 GeV. La présente analyse utilise les données collectées par ATLAS en 2015, 2016 et montre une meilleure sensibilité au signal due à l’augmentation de l'énergie des collisions au Run 2 jusqu'à 13 TeV. Cependant, les résultats sont compatibles avec les prédictions du modèle standard et ainsi les limites sur les masses de C1, N2 sont élevées et permettent d'exclure a 95% C.L. les modèles avec C1, N2 de moins de 680 GeV pour un N1 non massif. L'identification des b-jets joue un rôle important dans cette analyse. Dans cette thèse, on présente aussi des études sur la robustesse des performances du b-tagging avec diverses conditions de détection pour le détecteur a pixels, le plus important pour l'étiquetage de saveur des jets. Comme la plupart des recherches SUSY au LHC, cette analyse est effectuée en utilisant un modèle simplifié, ainsi le spectre de masse est choisi manuellement et les désintégrations SUSY considérées sont forcées. Suspect3 est l'un des outils théoriques utilisés pour interpréter les résultats de la recherche en modèles SUSY réalistes. Cette thèse présente la version SuSpect3 post-découverte du Higgs que nous développons. / During the LHC 8 TeV Run1, many searches were dedicated to the supersymmetric models. Among those, the search for the chargino-neutralino (C1, N2) pair production in final states with 1 lepton, 2 b-jets consistent with a Higgs boson and missing transverse energy. This search had negative outcome resulting in excluding C1, N2 masses up to 250 GeV for a massless lightest neutralino (N1) at 95% C.L.. The Run1 search used the 8 TeV ATLAS data collected in 2012. In this thesis, this search with ATLAS at LHC 13 TeV Run2 is presented, it uses 36.1 fb$^{-1}$ ATLAS data collected in 2015 and 2016. This Run 2 search provides an unprecedented sensitivity to high mass C1, N2 production. However, no evidence of new physics is observed and tighter new limits are placed on the C1, N2 production, with significant improvements over previous searches: C1, N2 masses up to 680 GeV for a massless N1 are excluded at 95% C.L. The identification of b-jets plays a significant role in this analysis. In this thesis, we present studies of the robustness of b-tagging performance with various conditions of the pixel detector, being the most important sub-detector for b-tagging. As most SUSY searches at the LHC, this analysis is carried out using Simplified Model of SUSY, i.e. the mass spectrum is chosen by hand and the considered SUSY decays are forced. Suspect3 is one of the theory tools utilized to map the search result into realistic SUSY models. This thesis presents the post Higgs discovery SuSpect3 version we have been working on. This version takes advantage of the very important new Higgs boson mass input to constrain other basic model parameter currently given as an input.

Este trabalho teve como objetivo, investigar como se dá a prática pedagógica nos anos iniciais do ensino Fundamental I em relação a abordagem da Cartografia Escolar. Nossa investigação pretendeu compreender como os professores se apropriam e auxiliam seus alunos a se apropriarem da linguagem cartográfica a partir da utilização de um Atlas Municipal, produtos cartográficos e outros recursos, tais como mapas, maquetes, croquis, bússolas, GPS, etc., e se conseguiriam a partir deste uso trabalhar conteúdos da geografia e de outras áreas do currículo escolar. Entendendo não ser tarefa fácil ao professor formado em Pedagogia, desenvolver os conteúdos próprios da Geografia devido a lacunas em sua formação que não priorizam conteúdos próprios da Geografia e tampouco da Cartografia Escolar. Sendo assim pautada pela observação e posterior análise das dificuldades apresentadas pelos professores do município de Itapeva-SP que atuam do 1º ao 5º ano, ao transporem didaticamente os conhecimentos cartográficos em sala de aula, elaboramos um curso de formação continuada que teve como mote uma metodologia que auxiliasse a se apropriarem dos conceitos e habilidades relativos a linguagem cartográfica e articulassem às suas próprias realidades, podendo assim transpor esses conhecimentos aos alunos. Para este intento, formulamos um conjunto de sequências de atividades didáticas, com as quais pretendíamos investigar o processo de desenvolvimento do raciocínio espacial dos professores e dos alunos, tendo assim a intenção de contribuir com uma proposta metodológica de trabalho para a Cartografia Escolar, que entre outros produtos utilizou de um Atlas Municipal Escolar, para explorar a realidade próxima de seus alunos e professores. Utilizamos como aporte teórico autores como: Almeida (1994); Callai (2005); Castellar (Rufino, 1996, 2005, 2010); Martinelli (1997); Simielli (1995, 2007); Oliveira (1978) entre outros e para a compreensão acerca da formação docente nos fundamentamos em Tardif (2009, 2012) e Nóvoa (1992). Partindo de uma abordagem pautada pela pesquisa qualitativa interpretativa, concluímos que o encaminhamento da proposta metodológica do curso foi apropriada e profícua, na medida em que valorizamos a participação efetiva tanto dos professores como dos alunos, procurando proporcionar-lhe os procedimentos necessários para que possam trabalhar com autonomia e segurança ao tratar da linguagem cartográfica, o que certamente lhes proporcionará um aprendizado contínuo e consequentemente um ensino significativo a seus alunos à medida que entenderão com maior clareza seus papéis no espaço da sociedade e lugar onde vivem e atuam. / This assignment was aimed to investigate how pedagogical practice makes up in the early years of Elementary School I, related to Scholar Cartography approach. Our research meant to understand how teachers take ownership and help their students to do so, of the cartographic language, from the use of a Municipal School Atlas, cartographic products and other resources, such as maps, models, sketches, compasses, GPS, etc.. and if they would make it through this use, to work Geography and other areas contents from the school curriculum.Recognizing it, as a non easy task to the teacher graded in Pedagogy, developing their own Geography contents, due to the gaps in their training, which does not prioritize them, neither Scholar Cartography.Guided this way by observation and further analysis of the difficulties, faced by teachers working in the town of Itapeva-SP, from the 1st and 5th year, when didactically crossing cartographic knowledge in the classroom, we developed a continuing education course that had as its motto, a methodology which would help them to take over the concepts and skills related to cartographic language and articulate to their own realities, in order to transpose this knowledge into the classroom.For this purpose, we have formulated a set of sequences of learning activities with which we intended to investigate the teachers and students spatial reasoning development process, in order to contribute to a work methodology for Scholar Cartography, that among other products, made use from a Municipal Atlas, to explore the close reality of their students and teachers.As theoretical contribution we made use of the following authors: Almeida (1994); Callai (2005), Castellar (Rufino, 1996, 2010); Martinelli (1997); Simielli (1995, 2007); Oliveira (1978) among others and for the comprehension of teacher education, we were based upon Tardif (2009, 2012) and Nóvoa (1992).Heading from an approach guided by the interpretive qualitative research, we conclude that the course methodological proposal routing was appropriate and useful, as we value the effective participation, both from the teachers and the students, seeking to provide them with the necessary procedures so they can work with autonomy and security when dealing with cartographic language, which certainly will provide them with an ongoing learning pursuant to a significant teaching to their pupils as they will understand clearer their roles in society space so where they live and work.

Este trabalho apresenta um estudo sobre as representações e o imaginário da arquitetura e do espaço construído pelo viés da mobilidade das imagens, a partir da análise e interpretação de três obras cinematográficas que se constituem como os objetos de estudo: Alice nas Cidades (1974), Dogville (2003) e Solaris (1972). Os filmes são abordados quanto à característica de apresentação do espaço de cada obra: tem-se então a cidade real (Alice nas Cidades), a cidade sugerida (Dogville) e a cidade imaginada (Solaris). Ao longo do texto são percorridos caminhos teóricos que partem das conexões entre cinema e arquitetura, cinema e imaginário e chegam na técnica da montagem, mostrando como esta pode servir não somente à narrativa fílmica, mas também como processo formativo de construção de imagens e significados através da justaposição de imagens e do processo de colisão entre elas. Ao transformar frames das obras cinematográficas em reproduções fotográficas, é convocado o Atlas Mnemosyne, painéis de imagens da autoria do historiador alemão Aby Warburg, como guia na construção de constelações de imagens. Entendendo o processo de feitura da Mnemosyne como uma técnica da montagem, as reproduções fotográficas vão sendo transformadas em narrativas outras por meio das constelações e galáxias de imagens, trabalhando com os conceitos de escala, dimensionamento, intervalo, aproximações e saltos das imagens; movimentos esses que encontram paralelo não somente no cinema - closes, travelling, saltos no tempo e no espaço -, como também no percurso dentro do espaço construído e nas representações da arquitetura. / This research presents a study about architecture\'s representations and imaginary, and its constructed space through the point of view of the mobility of images, from analysing and interpreting three cinematographic works that constitute the objects of study: Alice in the Cities (1974), Dogville (2003) and Solaris (1972). Each film is approached as to its characteristic presentation of space: the real (Alice in the Cities), the suggested (Dogville) and the imagined city (Solaris). Throughout the text, theoretical paths are drawn from connections between cinema and architecture, cinema and imaginary, and lead us to the technique of montage, showing how it can serve not only to the film narrative but also as a formative process of constructing images and meanings through the juxtaposition of pictures and the process of collision between them. By transforming frames of the cinematographic works into photographic reproductions, the Atlas Mnemosyne, panels of images by the German historian Aby Warburg, is called as a guide in the construction of constellations of images. Understanding the Mnemosyne process as a montage technique, photographic reproductions are transformed into other narratives through the constellations and galaxies of images, working with the concepts of scale, sizing, interval, approximations and jumps of images; movements that find parallel not only in cinema - closes, travelling, jumps in time and space - but also in the course within constructed space and in representations of architecture.

Das Modell einer vierten Familie konnte bis heute aufgrund von theoretischen Argumenten nicht ausgeschlossen werden. In dieser Arbeit wird die Suche nach einem Down-artigen Quark der vierten Familie mit dem folgenden angenommenen Zerfall: pp -> b''b''bar+X -> t+W+tbar+W+X -> bbar+W+W+W+W+X vorgestellt. Für diese Analyse wird eine integrierte Luminosität von 2.05 fb−1 verwendet, aufgenommen mit dem ATLAS Experiment bei einer Schwerpunktsenergie von sqrt(s) = 7TeV für die Proton-Proton Kollisionen am Large Hadron Collider. In der Analyse werden Ereignisse mit zwei gleich geladenen Leptonen (e oder mu) in den Endzuständen selektiert, was eine seltene Signatur im Standard Modell darstellt. Neben einer verwendeten Standardselektierung für die Ereignisse, entnommen aus der ATLAS Top-Quark Analyse, wird eine Optimierung der Schnitte mit einer multivariaten Analyse durchgeführt. Des Weiteren werden systematische Unsicherheiten studiert, die durch die Partonendichteverteilungsfunktion sowie durch Abstrahlung von Teilchen wie Gluonen im Anfangs- und im Endzustand bei der Simulation mit dem Monte Carlo Generator entstehen. Mit den selektierten Ereignissen in der Signalregion von zwei gleich geladenen Leptonen wird durch eine Zählanalyse die Anzahl gemessener Signalereignisss extrahiert. Mit diesen Signalereignissen wird dann die untere Massenausschlussgrenze des b''-Quarks mit einer modifizierten Frequentistmethode bestimmt. Das Ergebnis zeigt, dass mit einem angenommenem Verzweigungsverhältnis von 100 % für den Zerfall b'' -> t + W alle Massen unterhalb einer Grenze von 461 GeV mit einem 95 % Konfidenzintervall ausgeschlossen sind. / The model of a fourth generation is currently not excluded by theoretical arguments. In this thesis a search for a fourth generation down-type quark is presented with the decay hypothesis: pp -> b''b''bar+X -> t+W+tbar+W+X -> bbar+W+W+W+W+X The search is performed with an integrated luminosity of 2.05 fb−1 , obtained with the ATLAS experiment at the Large Hadron Collider running proton-proton collisions at a center-of-mass energy of sqrt(s) = 7TeV. Events for the analysis are selected with a search signature of two same-sign charged leptons (e or mu) in the final state, which is a rare Standard Model signature. Beside using the standard event selection from ATLAS top analyses, the event selection criteria are optimized with a multivariate analysis in order to maximize the significance. Furthermore, systematic uncertainties are studied coming from the parton distribution function as well as the initial and final state radiation. With the selected events in the signal region of two same-sign leptons, the signal is extracted via a counting method. The extracted signal is used for the determination of the mass limit of the fourth generation down-type quark with a modified frequentist method. Assuming a branching ratio of 100 % for the decay b'' -> t+W , b'' masses below 461 GeV are excluded at 95 % confidence level.

Le sujet de ma thèse traite les changements paléoenvironnementaux et paléoclimatiques qui ont affecté les écosystèmes du Moyen Atlas marocain depuis la dernière période glaciaire, centrée autour de 25,000 cal BP. Les trois séquences sédimentaires étudiées dans cette thèse ont été prélevées le long d'un transect Nord-Sud dans le Moyen Atlas. Cette étude est basée sur une approche multi-bioindicateurs intégrant la palynologie, la géochimie élémentaire et la granulométrie afin de comprendre la dynamique des écosystèmes passés et de mettre en évidence les impacts anthropiques sur ces écosystèmes et leurs bassins versants. Les résultats obtenus montrent que durant la dernière période glaciaire et jusqu’au début de l’holocène, une végétation steppique a dominé les paysages du Moyen Atlas en réponse à des conditions climatiques froides et arides. Cependant, des populations de cèdres, de chênes et de pins ont persisté durant la période glaciaire dans des micro-refuges. Bien que le début de l’holocène révèle une expansion des chênes et des pins (principaux composants des écosystèmes forestiers méditerranéens), la steppe (composée d'armoise, de chénopodiacées et de graminées) a persisté jusqu’à 6.5 ka cal BP. Ces écosystèmes tolérant à la sécheresse reflètent un début de l’holocène chaud mais avec une quantité de précipitations annuelles assez réduite pour permettre l'expansion des forêts tel que nous l'observons en Europe et d’autres régions de la Méditerranée. Ce n'est qu'à partir de 6.5 ka cal BP que les forêts de cèdre s’installent aux altitudes des sites étudiés (autour de 1600m) et que des plantes aquatiques prolifèrent dans les marais ou nous avons effectué les sondages. Nous observons ensuite une nette régression du couvert arboré à partir de 4.5 ka cal BP, notamment les chênes décidus, et une expansion des taxons herbacés. Ceci est le résultat d’une tendance vers des conditions plus arides témoignant d'une installation du climat méditerranéen tel que nous le connaissons aujourd'hui. Le début des changements environnementaux liés à l'impact humain, à travers les données palynologiques et géochimiques, n'est enregistré qu’à partir de ca. 1500 cal BP. Les résultats obtenus dans cette thèse sont en accord avec ceux d'autres études paléoenvironnementales menées en Méditerranée autant pour la période glaciaire que pour le début des conditions arides à partir de 5.5 ka cal BP. / This thesis discusses the paleoenvironmental and paleoclimatic changes that have affected the ecosystems of the Moroccan Middle Atlas since the last glacial period, and focuses around 25000 cal BP. The three sedimentary sequences that have been studied in this thesis were taken along a North-South transect in the Middle Atlas. This study is based on a multi-bio-indicators approach, including palynology, geochemical elements and particle size, in order to better understand the dynamic of previous ecosystems and to highlight the human activities on these ecosystems and on their catchment areas.The results obtained show that during the last glacial period, and until the beginning of the Holocene, steppe vegetation was predominant in the Middle Atlas, in reaction to cold and arid climate conditions. However, populations of cedars, oaks and pine trees remained in micro-refugia. Although the beginning of the Holocene reveals an expansion of oaks and pines trees (the main components of Mediterranean forests ecosystems), the steppe (which is composed of Artemisia, Chenopodiaceae and grasses) persisted till 6.5 ka cal BP. These drought-tolerant ecosystems reflect a warm beginning of the Holocene, with an amount of precipitation that was low enough to allow the expansion of forests similar to those we can observe in Europe and other areas of the Mediterranean. It’s only since 6.5 ka cal BP that cedars forests have started to grow at the altitudes of the sites we studied (around 1600m), and that aquatic plants have proliferated in the marshes where we took our samples. We can then observe a sharp decline of tree cover, including deciduous oaks, starting 4.5 ka cal BP and an expansion of herbaceous taxa. These are the consequences of a tendency to conditions that were more arid, attesting the installation of the Mediterranean climate as we know it today. The first environmental changes linked to human impact have only been recorded, through palynology and biochemical data, from ca. 1500 cal BP. The results obtained in this thesis are in line with those obtained in other paleoenvironmental studies conducted in the Mediterranean area, for the glacial period as well as for the beginning of arid conditions starting 5.5 ka cal BP.

Le travail scientifique présenté dans cette thèse s’appuie sur des collisions proton proton, à 13 TeV dans le centre de masse, produite par le grand collisionneur de Hadron (LHC) et enregistrées entre 2015 et 2017 par le détecteur ATLAS. Après une brève introduction sur le programme de physique du LHC, le premier chapitre donne un aperçu complet du contexte et des motivations théorique. Ensuite une description complète du détecteur ATLAS et plus généralement de l’ensemble expérimental est donnée. Le troisième chapitre traite d’une des mesures des performances du calorimètre électromagnétique ATLAS, à savoir l’étude des efficacités identification électronique à l’aide de W se désintégrant en électrons et neutrinos.Dans les chapitres suivants, le coeur de cette thèse, la recherche et l’étude de la production associée de boson de Higgs avec une paire de quark top, appelée production ttH, est traitée dans le schéma du modèle Standard et au-delà. L’observation de la production ttH avec le détecteur ATLAS a été récemment annoncée en 2018 et représente une étape importante pour le domaine de la physique des hautes énergies. Afin d’élargir le spectre de cette analyse tth au-delà du SM, cet état final du canal 4L a aussi été étudié dans le cadre de la recherche de bosons de Higgs doublement chargés se désintégrant en W$^{\pm}$W$^{\pm}$, H$^{\pm \pm} \rightarrow $ W$^{\pm}$W$^{\pm}$. En conclusions, les perspectives sur les futurs résultats scientifiques dans le modèle Standard (SM) ainsi que au-delà de SM (BSM) qui pourraient être atteint en utilisant les statistiques complètes des Run1 et Run2 combinés sont donnés. / The scientific work presented in this thesis is based on proton proton collision produced, at 13 TeV in the center of mass, created by the Large Hadron Collider (LHC) and recorded between 2015 and 2017 by the ATLAS detector.After a short introduction on the physics program at LHC, the first chapter gives a comprehensive overview of the theoretical context and motivation. Then a complete description of the ATLAS detector and more generally the experimental setup is given with a highlight on the different physics objects used in this research.The third chapter is dealing with a measure of the performances of the ATLAS electromagnetic calorimeter, namely the study of the electron identification efficiencies using W decaying into electrons and neutrinos events.In the following chapters, the core of this thesis work, the search and study of the associated Higgs boson production with top quark pair, so-called ttH production, within the Standard Model schema and beyond is treated. The observation for ttH production with the ATLAS detector recently announced in 2018 represents a significant milestone for the High-Energy Physics field. In order to broaden the spectrum of this ttH analysis beyond the SM, this 4L channel final states was also studied in the context of the search for doubly charged Higgs boson decaying into W±W±, H±±→W±W±.In conclusions, future prospects in Standard Model (SM) as well as Beyond SM (BSM) scientific results that could be reached using the full Run1 and Run2 combined available statistics are given.

Função-historiador é o termo apresentado nesta tese como proposta teórica de uma nova relação entre artes visuais e conflitos políticos no cenário artístico contemporâneo, para a qual a prática artística de Walid Raad sobre as guerras civis libanesas ocorridas entre 1975 e 1990, concentrada no Projeto Grupo Atlas (1989-2004), é fundamental. Observando a reunião de dossiês, documentos, arquivo, textos e conferências performáticas que formam esse extenso, complexo e multifacetado trabalho, a tese propõe similaridades entre os materiais, estruturas e procedimentos que o constituem e os recursos utilizados pelo campo da história na construção de suas narrativas. O argumento é que por meio dessas aproximações pode-se identificar interações entre artes visuais contemporâneas e conflitos políticos que se elaboram pela via de um interesse, inteligência e ambição históricos. Mais especificamente, reconhecemos que por meio da semelhança dos recursos plásticos, o Projeto Grupo Atlas apresenta, no campo das artes, formas de compor/contar histórias sobre guerras civis libanesas. Nisto, essa prática artística distingui-se das preocupações habituais em relação à discursos de memória e os limites de representação da experiência de violência, tão presentes em trabalhos centrados neste recorte temático específico. Sua aproximação com a história tem por fundamento uma cisão entre um sujeito-artista Raad e uma posição-de-autoria artística que funda o trabalho de arte, evitando-se que uma experiência de conflito do artista seja tomada como ferramenta explicativa de sua prática. A função-historiador, enquanto atividade, é reconhecida no nível das produções artísticas, na junção de uma série de elementos, discutidos nesta tese, por meio dos quais identificamos uma autoridade artística no Projeto Grupo Atlas que propõe formas de compor/contar histórias sobre conflitos políticos recentes, ao mesmo tempo em que, por meio delas, formula críticas aos métodos de composição de narrativas históricas. / Function-historian is the term presented in this thesis as a theoretical proposal of a new relationship between visual arts and political conflicts in the contemporary artistic scene, to which Walid Raad\'s artistic practice on the Lebanese civil wars between 1975 and 1990, concentrated in the The Atlas Group Project (1989-2004) is fundamental. The thesis proposes similarities between the materials, structures and procedures that constitute it and the resources used by the field of history in the construction of its narratives. The argument is that through these approaches we can identify interactions between contemporary visual arts and political conflicts that are elaborated through historical interest, intelligence and ambition. More specifically, we recognize that through the resemblance of plastic resources, he Atlas Group Project presents, in the field of the arts, ways of compose/tell stories about Lebanese civil wars. In this, this artistic practice distinguishes itself from the habitual preoccupations with the discourses of memory and the limits of representation of the experience of violence, so present in works centered in this specific thematic cut. His approach to history is based on a split between an artist-subject Raad and an artistic position of authorship that ground the work of art, avoiding that an experience of conflict of the artist is taken as an explanatory tool of his practice. The function-historian, as an activity, is recognized at the level of artistic productions, at the junction of a series of elements, discussed in this thesis, through which we identify an artistic authority in the Atlas Group Project that proposes ways of composing/ telling stories about recent political conflicts events, while at the same time criticizing the methods of composing historical narratives.