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The experiments discussed in this thesis exploit parity violation in elastic electron proton scattering in order to measure properties of the nucleon. Both experiments make use of the high quality, highly polarized electron beam available at Thomas Jefferson National Accelerator Facility. Q_weak will measure the weak mixing angle, sin²θ_W, via a measurement of the weak charge of the proton, at a four-momentum transfer, Q² ~ 0.026 GeV²/c². The precision of this measurement gives Q_weak access to new physics at the scale of 2.3 TeV, making it a test of the standard model. The G⁰ experimental program provides the fully separated contributions of the strange quark to the charge and magnetization distributions of the nucleon at two different values of four-momentum transfer, Q² ~ 0.22 and 0.63 GeV²/c². The measurement of the strange quark content of the proton in the G⁰ experimental program and other parity-violating electron scattering experiments provides a measurement of the hadronic contribution to the asymmetry in Q_weak. In addition, G⁰ was able to measure the parity-conserving beam normal single spin asymmetries that provide a measurement of the imaginary part of two photon exchange. The measurement of this asymmetry is necessary to understand the systematic contribution to measurements of parity-violating asymmetries, but it is also an important physics result. Recent theoretical work has shown that higher order radiative effects, such as two photon exchange, may be able to explain discrepancies between experiments which measure the ratio of the electric and magnetic form factors of the proton. The measurement of the transverse or beam normal single spin asymmetries provides a benchmark for theories that estimate the size of radiative corrections that are important for precision electroweak scattering experiments such as those described in this thesis. The results of the measurement of the transverse asymmetries at backward angles in G⁰ are presented at the two values of Q² ~ 0.22 and 0.63 GeV²/c² for hydrogen. Results for deuterium, which can provide the first measurements of the beam normal single spin asymmetries on the neutron, are also presented. / Ph. D.

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.

L'International Linear Collider (ILC) est un projet de futur collisionneur électron positron opérant à une énergie nominale dans le centre de masse de 500 GeV. Il fera des mesures de précision, par exemple d'un boson de Higgs léger qui pourrait être bientôt découvert au Large Hadron Collider. Les détecteurs de l'ILC prévus à cet effet seront composés de calorimètres à haute granularité.Cette thèse présente l'étude de la réponse d'un calorimètre électromagnétique silicium tungstène hautement granulaire (ECAL SiW) ainsi que l'étude de la production du quark top à l'ILC.Le prototype d'un ECAL SiW développé par la collaboration CALICE a été testé sous faisceaux de particules chargées au FNAL en Mai et Juillet 2008. Après avoir sélectionné des pions chargés négativement et entrant dans le ECAL, sa haute granularité est mise à profit pour introduire une classification en quatre types d'événements, afin de décrire des interactions hadroniques.Des modèles de dimensions supplémentaires expliquent l'anomalie AFBb du LEP par une modification des couplages des quarks de troisième génération au boson Z. Ces effets motivent l'étude de la désintégration semileptonique des paires de quarks top, effectuée ici au moyen d'une simulation complète du détecteur ILD proposé pour l'ILC à une énergie dans le centre de masse de 500GeV pour une luminosité intégrée L = 500 fb-1. Les performances de ce détecteur permettent d'atteindre des efficacités de sélection de plus de 70% avec une pureté meilleure que 95%. Cela se traduit par une précision relative d'environ 1% sur l’asymétrie gauche-droite de la production du quark top ALR ainsi que sur l'asymétrie avant-arrière du quark top AFBt dans le cas où les électrons sont polarisés à 80% et pas les positrons. Les incertitudes relatives sur les couplages gauche et droit du quark top au boson Z peuvent aller jusqu'à 0.9% et 1.5%. / The International Linear Collider (ILC) is a proposed e+e- collider with a center-of-mass energy of 500 GeV or more, aimed at precision measurements, e.g. of a light Higgs boson that could be discovered soon at the Large Hadron Collider. Its detectors foresee the use of fine grained calorimeters to achieve the desired precisions.This thesis presents the study of the response to hadrons of a highly granular silicon-tungsten electromagnetic calorimeter (SiW ECAL), and the study of top quark pair production at the ILC.The SiW ECAL prototype developed by the CALICE collaboration was tested with beams of charged particles at FNAL in May and July 2008. After selecting single negatively charged pions entering the ECAL, its fine granularity is used to introduce a classification among four types of events, used to describe hadronic interactions.Motivated by extra-dimensional models which may explain the AFBb LEP anomaly by modifying the couplings of third generation quarks to the Z boson, the semileptonic decay of the top quark is studied with a full simulation of the proposed ILD detector for the ILC at center-of-mass energy of 500 GeV and integrated luminosity of 500 fb-1. Detector performances permit to reach efficiencies larger than 70% in finding those events with purity larger than 95%. This translates into a relative accuracy of about 1% on both the left-right asymmetry of top production ALR and the top forward-backward asymmetry AFBt with electrons polarized at 80% and no polarization of the positrons. The relative uncertainties in the left and right couplings of the top quark to the Z boson could be as good as 0.9% and 1.5%.

O Plasma de Quarks e Glúons (Qgp), um meio denso e quente, pode ser produzido em laboratório a partir da colisão entre íons pesados relativísticos. Pode-se estudá-lo a partir da comparação entre jatos reconstruídos em tais eventos e aqueles reconstruídos em colisões próton-próton, uma vez que se espera que os pártons ao atravessarem o Qgp percam energia em função da interação com o meio, o chamado jet quenching. Este trabalho propõe dois novos observáveis no estudo de jatos reconstruídos em colisões entre íons pesados relativísticos: o espectro de jatos quasi-inclusivo e a evolução do espectro de jatos de recuo em função da partícula trigger. Mostra-se que conhecida a função de resolução do momento reconstruído do jato é possível obter o espectro verdadeiro desses observáveis a partir da técnica de deconvolução bayesiana iterativa. A técnica proposta é empregada em eventos de colisões núcleonúcleo realizadas nos aceleradores Rhic e Lhc cujos dados foram coletados pelas colaborações Star e Alice, respectivamente. Os resultados evidenciam a ocorrência do fenômeno de jet queching independentemente do sistema, da energia e da centralidade da colisão em um grande intervalo cinemático. / The Quark-Gluon Plasma (Qgp), a hot and dense medium, can be produced in laboratory by colliding relativistic heavy ion. This medium can be studied by the comparison of jets reconstructed in such events and those reconstructed in proton-proton collisions, once it is expected that partons lose energy when traversing the Qgp due to its interaction with the medium, the so-called jet quenching. This work proposes two new observables: the quasiinclusive jet spectrum and the evolution of the recoil jet spectrum as function of the trigger particle. It is shown that it is possible to obtain those spectra using iterative bayesian unfolding, which requires the resolution function for the reconstructed jet transverse momentum. This technique is applied to Star and Alice data which has been taken at Rhic and Lhc, respectively. The results indicate that jet quenching occurs in a very wide kinematic range, regardless the colliding system, its energy and centrality.

The Standard Model of particle physics is currently the most complete theory of subatomic particles. The discovery of the Higgs boson with a mass of 125 GeV in 2012 further validated the Standard Model, providing evidence for the theory that vector bosons obtain non-zero masses through the Higgs mechanism. Studies are ongoing to determine the exact nature and properties of the Higgs boson. A Higgs boson of this mass is predicted to decay to a pair of b-b quarks with a branching ratio of 58%, however this decay mode has not yet been observed. This thesis presents a search for the associated production of a Higgs boson with a leptonically decaying W boson, WH → ℓvb-b, using 20.3 fb-1 of Run 1 data collected by ATLAS at the LHC from pp collisions at a centre-of-mass energy of ps = 8 TeV. The observed (expected) significance of a Higgs boson with a mass of 125 GeV for the WH → ℓvb-b process is found to be 2:7σ (1:3σ). The measured cross section in units of the expected Standard Model cross section has a best-fit value of μ = μ/μSM = 2:2+0:67-0:64(stat:)+0:7-0:59(syst:) = 2:2+0:97-0:87. The results are combined with the search for ZH → v-vb-b and ZH → ℓ+ℓ-b-b to provide a best-fit value of μ = μ/μSM = 1:1+0:61-0:56. The start of Run 2 of the LHC in 2015 saw the collision energy being raised to √s = 13 TeV, increasing the probability of particles being produced with a large momentum boost. At these high energies there is also a possibility to discover new particles and interactions. An extension of the Standard Model, the Heavy Vector Triplet (HVT) model, describes new heavy vector bosons W¹ and Z¹, which can decay to pairs of heavy bosons (W, Z or Higgs bosons). If the W0 and Z0 bosons are sufficiently heavy, the hadronic decays of the diboson final states produce boosted jets. In this thesis, methods for identifying hadronically decaying boosted bosons are developed, based on techniques that examine the internal substructure of the jet. Multiple substructure variables are combined into a single discriminant using two machine learning techniques: boosted decision trees and deep neural networks. Simulated events of W¹→WZ → q-qq-q are used to develop these boosted W boson taggers. An improvement in the background rejection power, whilst keeping 50% of the signal, over previous boosted W boson taggers of up to 13%-when using deep neural networks-and 36%-when using boosted decision trees-is obtained. The performance of the new boosted W boson taggers are evaluated in a search for a narrow WW resonances from the decay of a Z¹ with boson-tagged jets in 3.2 fb-1 of pp collisions at √s = 13 TeV collected with the ATLAS detector.

Encontrar formas de reutilizar os resíduos oriundos da produção de alimentos é uma necessidade cada vez mais presente nas indústrias tanto do ponto de vista ambiental como financeiro. Este trabalho teve por objetivo incorporar soro ácido na base láctea e no preparado de frutas de uma bebida láctea fermentada sabor morango e avaliar a interferência destas variáveis independentes nas características físico-químicas e reológicas do produto, bem como o efeito do tempo nestas respostas. O planejamento experimental seguiu o delineamento fatorial completo do tipo rotacional, com duas variáveis explanatórias. Os níveis de soro ácido variaram nas formulações, sendo na base láctea aplicadas menores dosagens (de 0 a 10%) devido a limitação por causa da precipitação da caseína em pH ácido no tratamento térmico. No preparado de frutas a dosagem de soro ácido variou de 0 a 30%. Os tratamentos (base láctea adicionada de preparado de frutas) foram acondicionados em potes de polipropileno e estocados a 8°C. Semanalmente foram feitas as análises físico-químicas de pH, acidez e sinerese além das análises reológicas. A análise dos dados foi feita pelo método de superfície de resposta e análise de regressão múltipla. Os tratamentos foram avaliados quanto a composição centesimal após 21 dias de estocagem pela análise dos teores de gordura, cinzas, proteínas e matéria sólida total, seguindo posteriormente com o cálculo de carboidratos e valor energético. A contagem de bactérias láticas foi feita por plaqueamento em MRS (Man Rogosa & Sharpe) Ágar após 21 dias de estocagem para garantir a contagem mínima exigida no tempo de vida útil final do produto. Todos os resultados obtidos nas análises de composição centesimal e microbiológicas se enquadraram nos limites da legislação vigente. De forma geral o percentual de soro ácido aplicado no preparado de frutas não influenciou os parâmetros físico-químicos avaliados, exceto para a viscosidade em que foi identificado efeito estatisticamente significativo indicando que o aumento nos níveis utilizados aumentam a viscosidade. A utilização do soro ácido na base láctea ocasionou aumento da acidez e diminuição da sinerese, estando os resultados de acidez em concordância com os dados da literatura para estudos semelhantes. O aumento do percentual de soro na base promoveu redução na viscosidade, afetando negativamente este parâmetro, porém, alternativas tecnológicas (uso de espessantes, pressão de homogeneização, temperatura no tratamento térmico, entre outras) podem suprir a perda de viscosidade apresentada. Todos os tratamentos apresentaram comportamento não-newtoniano e tixotrópico. / Finding ways to reuse waste from food production is an increasing necessity in this industry both for environmental and financial reasons. This study aimed to incorporate acid whey in milk-based and fruit prepared of a fermented dairy drink, strawberry flavor, and assess the effect of these independent variables on the physicochemical and rheological characteristics of the product as well as the effect of time on these responses. The experimental design followed a complete factorial design of the rotational type, with two explanatory variables. Acid whey levels ranged in the formulations being applied to dairy-based lower doses (from 0 to 10%) due to a limitation because of the precipitation of casein at acidic pH during heat treatment. In the fruit prepared the dosage of acid whey ranged from 0 to 30%. Treatments (milk added base of fruit prepared) were placed in polypropylene pots and stored at 8°C. Physicochemical analysis of pH, acidity and syneresis beyond rheological analyzes were conduced weekly. Data analysis was performed by the response surface method and multiple regression analysis. Treatments were nutritionally assessed after 21 days of storage by the analysis of the levels of fat, ash, protein and total solids, later following with the calculation of carbohydrates and energy value. The count of lactic acid bacteria was carried out by plating on MRS (Man Rogosa & Sharpe) Agar after 21 days of storage to ensure a minimum count time required in the final product shelf life. All results obtained in the analysis of chemical and microbiological composition fulfilled the bounds of current legislation. Overall the percentage of acid whey applied to the fruit prepared did not affect the physicochemical parameters evaluated, except for the viscosity in which was identified a statistically significant effect indicating that an increase in levels used, increase viscosity. The use of acid whey dairy based resulted in increased acidity and reduced syneresis, being acidity results in agreement with literature data for similar studies. The increase in the percentage of acid whey in the base promoted reduction in viscosity, adversely affecting this parameter, however, alternative technologies (use of thickeners, pressure homogenization, heat treatment temperature, etc.) can fill the given viscosity loss. All treatments showed non- Newtonian and thixotropic behavior.

O Plasma de Quarks e Glúons (Qgp), um meio denso e quente, pode ser produzido em laboratório a partir da colisão entre íons pesados relativísticos. Pode-se estudá-lo a partir da comparação entre jatos reconstruídos em tais eventos e aqueles reconstruídos em colisões próton-próton, uma vez que se espera que os pártons ao atravessarem o Qgp percam energia em função da interação com o meio, o chamado jet quenching. Este trabalho propõe dois novos observáveis no estudo de jatos reconstruídos em colisões entre íons pesados relativísticos: o espectro de jatos quasi-inclusivo e a evolução do espectro de jatos de recuo em função da partícula trigger. Mostra-se que conhecida a função de resolução do momento reconstruído do jato é possível obter o espectro verdadeiro desses observáveis a partir da técnica de deconvolução bayesiana iterativa. A técnica proposta é empregada em eventos de colisões núcleonúcleo realizadas nos aceleradores Rhic e Lhc cujos dados foram coletados pelas colaborações Star e Alice, respectivamente. Os resultados evidenciam a ocorrência do fenômeno de jet queching independentemente do sistema, da energia e da centralidade da colisão em um grande intervalo cinemático. / The Quark-Gluon Plasma (Qgp), a hot and dense medium, can be produced in laboratory by colliding relativistic heavy ion. This medium can be studied by the comparison of jets reconstructed in such events and those reconstructed in proton-proton collisions, once it is expected that partons lose energy when traversing the Qgp due to its interaction with the medium, the so-called jet quenching. This work proposes two new observables: the quasiinclusive jet spectrum and the evolution of the recoil jet spectrum as function of the trigger particle. It is shown that it is possible to obtain those spectra using iterative bayesian unfolding, which requires the resolution function for the reconstructed jet transverse momentum. This technique is applied to Star and Alice data which has been taken at Rhic and Lhc, respectively. The results indicate that jet quenching occurs in a very wide kinematic range, regardless the colliding system, its energy and centrality.

La première partie de cette thèse porte sur l'amélioration de l'algorithme de l'étape d'initiation de reconstruction des traces de hadrons et de muons au sein du trajectographe au silicium de l'expérience CMS. Les différentes étapes de mise au point et de tests, qui ont permis d'aboutir à la qualification de ce nouvel algorithme en tant que méthode standard d'initiation de la reconstruction des traces, sont présentées dans ce document.La deuxième partie concerne la mise en place d'une méthode alternative de mesure de la section efficace de production des paires top-antitop dans l'expérience CMS lors du démarrage du LHC. Cette analyse est effectuée à partir du canal de désintégration semi-muonique avec au moins un muon supplémentaire provenant d'un des quarks bottom et a été réalisée en simulation complète démontrant ainsi la possibilité d'une “redécouverte” possible du quark top avec 5 pb-1. Les 2.4 pb-1 de données réelles obtenues à la fin du mois d'Août m'ont permis d'observer les premières paires top-antitop et d'effectuer une première mesure de section efficace : 171±77(stat.) ±27(syst.) pb / The first part of this thesis is about the improve made to the seeding algorithm of track reconstruction for the hadrons and the muons in the silicon tracker of the CMS experiment. The different stages from the creation to the tests, which allowed us to qualify this new algorithm as the standard seeding for tracks reconstruction, are presented in this document. The second part is dedicated to the creation of an alternative method to measure the cross-section of the top-antitop pairs production in the CMS experiment at the LHC launch. This analysis has been made using the channel of the semi-muonic decay with at least one another muon coming from a bottom quark and has been studied on full simulation showing the feasibility to “re-discover” the top quark with 5 pb-1. The 2.4 pb-1 of data collected by the end of august have allowed me to observe the first top-antitop pairs and to make the first cross-section measurement: 171±77(stat.) ±27(syst.) pb.

Ce manuscrit décrit mon travail de thèse au sein de l’expérience CMS du collisioneur LHC. Il présente les deux sujets sur lesquels j’ai travaillé : un sujet orienté détecteur et un sujet orienté analyse de données. Le premier sujet, orienté détecteur, se situe dans le cadre du projet HL-LHCqui prévoit une augmentation de la luminosité instantanée d’un facteur cinq. Une telle augmentation et la conservation du système de haut niveaudu déclenchement (HLT), engendre de nouvelles contraintes sur le détecteurCMS. Notamment au niveau du système de déclenchement électronique. Lacollaboration CMS envisage d’implanter ce dernier au sein du détecteur detraces. Deux méthodes de déclenchement sont proposées : la méthode des modules empilés et la méthode des mémoires associatives. La méthode desmémoires associatives necessite toutefois une présélection intéligente des signauxélectriques pour être utilisable. La méthode de la largeur des amas estproposée conjointement par l’équipe de Fabrizio Palla (Pise) et par l’équipede Didier Contardo (IPNL) pour présélectionner les signaux. L’optimisation de cette méthode, en particulier des paramètres géométriques des modules etdes seuils appliqués pour la présélection des signaux électrique, est le résultatde mon travail. Il est détaillé tout au long de la partie III de ce manuscrit. Le deuxième sujet concerne l’analyse des données récoltées par CMS durant l’année 2011. Cette analyse a pour objectif de rechercher de nouvellesparticules dans le spectre de masse invariante top anti-top. De par sa grande masse, proche de la brisure électrofaible, le quark top joue un rôle prépondérantdans de nombreuses extensions du Modèle Standard. L’observation de résonances étroites dans le spectre pourrait en être le signe. L’analyseest subdivisée en trois parties : la sélection des évènements top anti-top, la reconstruction de la masse invariante top anti-top et une étude statistique pour quantifier la présence de nouvelle physique. Les résultats de ce travailsont des limites sur la section efficace de production de nouvelles particules.Ils sont présentés dans la partie IV du manuscrit. / This manuscript describes my thesis work within the CMS experiment ofthe LHC collider. It presents both subjects on which I worked : a detectorsubject and a data analysis subject. The first subject, detector, is situated within the framework of the HL-LHCproject which plans an increase by a factor five the instantaneous luminosity.Such an increase and the preservation of the high level trigger (HLT)system, generate new constraints on the CMS detector. This is particularly true for the electronic trigger (L1) system. The CMS collaboration intends to implant this within tracker detector. Two methods are proposed : the stubmodules method and the associative memorie method. However, associativememorie method require a clever preselection of electric signals to be usable.The cluster width method is jointly proposed by Fabrizio Palla’s team (Pisa) and by Didier Contardo’s team (IPNL) to preselecte electric signals. The optimization of this method, in particular geometrical parameters of modules and thresholds applied for the electric signals preselection, is the result of myown work. It is detailed throughout the part III of this manuscript. The second subject concerns the analysis of data collected by CMS during 2011. This analysis has for objective to look for new particles in the spectreof anti-top top invariant mass. Due to its big mass, close to the electroweak symmetry breaking energy, the top quark plays a important role in numerous extensions of the Standard Model. The observation of narrow resonances in the spectre could be the sign of new particles. The analysis is subdivided into three parts, the selection of top anti-top events, the reconstruction of top anti top invariant mass and a statistical study to quantify the presence of new physics. The results of this work are limits on the cross-section productionof new particles. They are presented in the part IV of this manuscript.