<p>Heavy flavor hadrons serve as valuable probes of the transport properties of the quark-gluon plasma (QGP) created in relativistic heavy-ion collisions. In this dissertation, we introduce a comprehensive framework that describes the full-time evolution of heavy flavor in heavy-ion collisions, including its initial production, in-medium evolution inside the QGP matter, hadronization process from heavy quarks to their respective mesonic bound states and the subsequent interactions between heavy mesons and the hadron gas.</p><p>The in-medium energy loss of heavy quarks is studied within the framework of a Langevin equation coupled to hydrodynamic models that simulate the space-time evolution of the hot and dense QGP matter. We improve the classical Langevin approach such that, apart from quasi-elastic scatterings between heavy quarks and the medium background, radiative energy loss is incorporated as well by treating gluon radiation as a recoil force term. The subsequent hadronization of emitted heavy quarks is simulated via a hybrid fragmentation plus recombination model. The propagation of produced heavy mesons in the hadronic phase is described using the ultra-relativistic quantum molecular dynamics (UrQMD) model. Our calculation shows that while collisional energy loss dominates the heavy quark motion inside the QGP in the low transverse momentum (pT) regime, contributions from gluon radiation are found to be significant at high pT. The recombination mechanism is important for the heavy flavor meson production at intermediate energies. The hadronic final state interactions further enhance the suppression and the collective flow of heavy mesons we observe. Within our newly developed framework, we present numerical results for the nuclear modification and the elliptic flow of D mesons, which are consistent with measurements at both the CERN Large Hadron Collider (LHC) and the BNL Relativistic Heavy-Ion Collider (RHIC); predictions for B mesons are also provided.</p><p>In addition, various transport properties of heavy quarks are investigated within our numerical framework, such as the thermalization process of heavy quarks inside the QGP, and how the initial configuration of the QGP as well as its properties affect the final state spectra and the elliptic flow of heavy mesons and their decay electrons. The effects of initial state fluctuations in heavy-ion collisions are also studied and found to enhance the heavy quark energy loss in a (2+1)-dimensional boost invariant scenario. Furthermore, a new set of observables -- heavy-flavor-tagged angular correlation functions -- are explored and found to be potential candidates for distinguishing different energy loss mechanisms of heavy quarks inside the QGP.</p> / Dissertation

This thesis presents gauge fixed gluonic observable and neutral Kaon mixing matrix element measurements using nf=2+1 Domain Wall Fermion (DWF) configurations. These were generated with the Iwasaki gauge action by the RBC and UKQCD collaborations. Results from the first measurement of the QCD strong coupling with these ensembles using the triple gluon vertex are shown. We find that while a very accurate measurement of the coupling is possible using this technique, the systematic error from the perturbative matching at current lattice scales is large. We also discuss the utilisation of this method as a probe for possible Technicolor theories. The calculation of the QCD strong coupling constant from the triple gluon vertex required an implementation of a fast code to fix lattice gauge configurations. I provide details on my implementation of a parallel and optimised Fourier-accelerated algorithm for both Landau and Coulomb gauge fixing. I include the first calculation of the highly accurate W0-scale using these ensembles, allowing for percent-level scale setting. I show results from a wide variety of smearing methods and present the first gluonic measurement of different smearing radii. This thesis also details the first nf=2+1 measurement of the BSM neutral Kaon mixing renormalised matrix elements from lattice simulations with almost exact chiral symmetry in the valence sector and the sea.

We solve a random matrix ensemble called the chiral Ginibre orthogonal ensemble, or chGinOE. This non-Hermitian ensemble has applications to modelling particular low-energy limits of two-colour quantum chromo-dynamics (QCD). In particular, the matrices model the Dirac operator for quarks in the presence of a gluon gauge field of fixed topology, with an arbitrary number of flavours of virtual quarks and a non-zero quark chemical potential. We derive the joint probability density function (JPDF) of eigenvalues for this ensemble for finite matrix size N, which we then write in a factorised form. We then present two different methods for determining the correlation functions, resulting in compact expressions involving Pfaffians containing the associated kernel. We determine the microscopic large-N limits at strong and weak non-Hermiticity (required for physical applications) for both the real and complex eigenvalue densities. Various other properties of the ensemble are also investigated, including the skew-orthogonal polynomials and the fraction of eigenvalues that are real. A number of the techniques that we develop have more general applicability within random matrix theory, some of which we also explore in this thesis.

O Plasma de Quarks e Glúons (Quark Gluon Plasma ou QGP) criado de forma sistemática em grandes aceleradores de partículas que envolvem colaborações do mundo inteiro, apesar de ter sua descoberta anunciada há bastante tempo ainda apresenta desafios e questões a serem respondidas tanto do ponto de vista experimental como do teórico. O objetivo deste trabalho é estudar a conexão entre as condições iniciais da expansão do QGP (que dependem da interação forte e não são acessíveis ao experimento) com a anisotropia da emissão azimutal das partículas (que por sua vez reflete as condições iniciais e é medida experimentalmente). O modelo hidrodinâmico é descrito inicialmente, com ênfase no programa NeXSPheRIO. Também são apresentadas alguns tipos de observáveis e modelos de condições iniciais (NeXus, MC-KLN e TRENTO). Por fim resultados de simulações para distribuições evento-por-evento do fluxo anisotrópico (facilmente ligadas aos modelos de condições iniciais) são comparadas com dados do LHC e previsões são feitas para a energia mais alta do RHIC. Estas previsões são testadas via a razão $v_2\\{4\\}/v_2\\{2\\}$ para a qual dados existem. / The Quark Gluon Plasma (QGP), created in a systematic way in large particle accelerators which are built by worldwide collaborations, even though its discovery being announced a long time ago it still presents us with challenges and questions to be answered even from the experimental point of view to the theoretical one. The main goal of this work is to study the connection between the initial conditions for the QGP expansion (which depend on strong interactions and are not accesible to the experiments) to the anisotropy in the azimuthal particle emission (which in turn reflects the initial conditions and is measured experimentally). The hydrodynamical model is described initially, with emphasis on the code NeXSPheRIO. Additionally some types of observables and initial condition models (NeXus, MC-KLN and TRENTO) are presented. And at last, results from simulations for event-by-event distributions for the anisotropic flow (easily connected to the initial conditions models) are compared with LHC\'s data and predictions are made for the RHIC\'s top energy. These predictions are tested by the $v_2\\{4\\}/v_2\\{2\\}$ for which data exists.

Nesta dissertação discutimos a medida RAA desenvolvida para análise de observáveis de colisão núcleo-núcleo (AA), tendo em vista sua implementação em colisões próton-próton (pp). No contexto das colisões hadrônicas de altíssimas energias, o RAA compara quantidade de observáveis duros medidos em colisões AA com a quantidade do mesmo observável em colisões pp. As qualidades destas colisões são descritas pela teoria do modelo de Glauber, em que projeção analítica da produção esperada de quarks pesados (observável duro) é realizada para colisões nucleares por meio da sobreposição de colisões pp independentes. Esta projeção analítica é comparada no RAA à medida de quarks pesados em estado final de colisões AA, e desvios em relação à distribuição de momentos da seção de choque calculada teoricamente são interpretados como decorrentes da presença de plasma de quarks e glúons (PQG) na colisão medida. O plasma de quarks e glúons é o objeto de interesse do campo de estudos em que esta pesquisa se insere. Considerado presente em colisões AA centrais desde 2000, o plasma de quarks e glúons é o estado da matéria mais energético possível, em que os pártons produto da colisão se comportam livremente por breves instantes e sofrem expansão hidrodinâmica. Este processo acontece nos estágios inacessíveis da colisão. Algumas das medidas indiretas que indicam formação de plasma em colisões AA são detectadas em colisões de sistemas pequenos, pp e pA desde 2010. Ainda não foi medida supressão de provas duras no PQG. As tentativas de medir PQG em sistemas pequenos pelo método do RAA tem sido feitas por meio da comparação RpA, também definida pelo modelo de Glauber. Na presente pesquisa buscamos extrapolar o funcionamento do RAA para medidas em colisões pp. Como o núcleo em Glauber é formado por sobreposição de prótons, a resolução da descrição da colisão na teoria é discutida. Além disso verificamos que a concepção de que colisões pp não formam ambiente de PQG é importante para o estabelecimento da comparação RAA. Entendemos que as hipóteses sobre a física de estágios inacessíveis da colisão previstas pela teoria de Glauber são diferentes das hipóteses decorrentes de medidas de coletividade em sistemas pequenos. Propomos alternativamente comparações experimentais simples entre quantidades parecidas medidas em colisões pp que podem conter informações sobre supressão de observáveis duros em colisões pp de alta multiplicidade sem o uso de quantidades teóricas. / This master thesis adresses the measurement RAA, developed for the analysis of nucleus-nucleus (AA) collisions, aiming to implement the measure for proton-proton (pp) collisions. In the context of high energy hadronic collisions, RAA compares hard observables measured in AA collisions with the same observable measured in pp collisions. These collisions traits are described by the Glauber model, where an analitical projection of the expected heavy quark production (hard observable) is calculated through the superimposition of independent pp collisions. In RAA, that analitical projection is compared to the actual final state AA collisions measurements, and deviations with relation to the momentum distribution of the theoriticaly calculated cross section are regarded as arising from interaction of the heavy quark with a quark gluon plasma (QGP) formed in the measured collision. The quark gluon plasma is the fields object of interest in which this reasearch is undertaken. Since 2000, QGP is measured and presumed in central AA colissions.The quark gluon plasma is the most energetic state of nuclear matter, in which partons behave as deconfined matter and undergo hydrodynamic expansion. That happends in the first inaccessible stages of the collisions. Some of the indirect measurements that point to the formation of QGP in AA collisions have been detected small systems, pp and pA, since 2010. Is yet to be measured hard probes PQG supression in these systems. Current attempts to evaluate this supression have been made with the RpA comparison, also defined with the Glauber model. In this study, we attempt to extrapolate the RAA operation to pp collision measurements. As the nucleus in Glauber is modeled as a superimposition of pp collisions, the theory\'s resolutuon in describing AA collisions is discussed. We also notice that the concept of pp collisions not formimg QGP is relevant for RAA comparisons. We appreciate that the theoretical hipothesis on the physics of the inaccessible first stages of collisions as foreseen with the Glauber model are different than the hipothesis that stem from collectivity in small systems. We propose alternatively simple experimental comparisons between similar quantities measured in pp collisions without the use of theoretical quantities.

Um novo estado, o Plasma Quark-Gluon (QGP), é formado quando a matéria comum formada por hadrons é submetida a condições extremas de temperatura e/ou densidade. Acredita-se que esse estado esteja presente nos primeiros momentos do universo e que seja relevante para entender propriedades da cromodinâmica quântica. O QGP é criado e caracterizado em aceleradores de partículas por meio de colisões de íons pesados. No entanto, uma estrutura alongada em psedorapidez (\\textit{double ridge}) na distribuição da correlação angular entre duas partículas foi encontrada em sistemas pequenos, como pp e p--Pb. Essa estrutura assemelha-se àquela observada nas colisões com íons pesados, onde sua interpretação está ligada ao comportamento coletivo que gera uma anisotropia azimutal nos produtos finais das colisões. Essa estrutura não era esperada em sistemas pequenos e sua interpretação física ainda está em debate, em particular no que diz respeito ao papel da hidrodinâmica e das condições iniciais. Uma medida para este efeito com partículas provenientes de quarks pesados ainda não haviam sido realizadas no momento em que este trabalho foi iniciado e esta medida poderia esclarecer questões sobre as diferentes interpretações. Os quarks pesados são uma sonda interessante caso o QGP seja formado devido ao seu tempo de formação inicial, reagindo a toda a evolução do meio. Neste trabalho, os quarks pesados são estudados medindo-se os elétrons provenientes dos decaimentos semi-leptônicos de hádrons que contêm quarks \\textit{charm} ou \\textit{beauty} e outros quarks leves (\\textit{open heavy flavor}). Os hadrons não são reconstruídos e usa-se um método de extração de sinal para remover elétrons de outras fontes. As correlações angulares de elétrons de decaimento de hadrons de quarks pesados com partículas carregadas em colisões de p--Pb a $\\sqrt{s_{m NN}}$ = 5,02 TeV medidos com o experimento ALICE em rapidez central ($ | \\eta | <0,8 $) são apresentadas. As distribuições mostram sinais de anisotropias azimutais que são quantificadas pelo coeficiente $ v_2 $. O $ v_2 $ para elétrons provenientes de quarks pesados é positivo com mais de $ 5 \\sigma $ de significância, fornecendo uma forte indicação de anisotropias azimutais similares ao \\textit{double ridge} para partículas contendo quarks pesados em colisões de alta multiplicidade de p--Pb. Esta é a primeira medida do $ v_2 $ para elétrons vindos de quarks pesados em colisões p--Pb. / A new state of mater, the Quark-Gluon Plasma (QGP), is formed when the ordinary hadronic matter is put under extreme temperature and/or density conditions. This state is believed to be present in the first moments of the universe and it is relevant to understand properties of the quantum chromodynamics. The QGP is created and characterized in particle accelerators by colliding heavy ions. However, a double-ridge long-range structure in the two-particle azimuthal correlation distribution was found in small systems, such as pp and p--Pb. This structure resembles the one observed in heavy-ion collisions, where its interpretation is linked to collective behavior that generates an azimuthal anisotropy in the final products of the collisions. This structure was not expected in small systems and its physical interpretation is still in debate, in particular regarding the role of hydrodynamics and initial conditions. A measurement for this effect with particles coming from heavy quarks was not done by the time this work started and this measurement could shed light into the different interpretations. Heavy quarks are an interesting probe in case the QGP is formed due to their early formation time, experiencing the whole evolution of the medium. In this work, heavy quarks are examined by measuring electrons originating from the semi-leptonic decays of hadrons that contain a heavy quark (charm or beauty) and other light quarks (open heavy flavor). The hadrons are not reconstructed and a signal extraction method is used to remove electrons from other sources. The azimuthal angular correlations of heavy-flavour hadron decay electrons with charged particles in p--Pb collisions at $\\sqrt{s_{m NN}}$ = 5.02 TeV measured with ALICE detector at mid-rapidity ($|\\eta| < 0.8$) are studied. The distributions show signs of azimuthal anisotropies which are quantified by the $v_2$ coefficient. The $v_2$ for heavy-flavor electrons is found to be positive with more than $5\\sigma$ significance, providing very strong indication of long-range azimuthal anisotropies for heavy-flavour particles in high multiplicity p--Pb collisions. This is the first measurement of the $v_2$ for electrons coming from heavy-flavor hadron decays in p--Pb collisions.

La chromodynamique quantique prédit, à haute température et/ou densité d'énergie, une transition de phase entre la matière hadronique ordinaire et un nouvel état où les quarks et les gluons seraient déconfinés : le Plasma de Quarks et de Gluons. Durant les quinze dernières années s'est développé un large programme expérimental au CERN et à Brookhaven, ayant pour but d'identifier le PQG. ALICE est l'expérience du LHC dédiée à l'étude du plasma via les collisions d'ions lourds ultra-relativistes à 2.75 TeV/nucléon et par faisceau. La mesure de la suppression des résonances de la famille du Upsilon, signature potentielle de la formation d'un milieu coloré, à l'aide du spectromètre à muons de l'expérience ALICE est au centre de cette thèse. La première partie de ce travail est liée à l'étude des chambres multifils à cathodes segmentées du bras dimuon, utilisées par le système de trajectographie des muons issus de la décroissance des résonances lourdes. La seconde partie présente un algorithme d'alignement des détecteurs à l'aide de traces physiques à même de mesurer les positions réelles des différentes composantes du système de trajectographie avec de très bonnes résolutions spatiales. Finalement, la dernière partie propose une étude à mener à l'aide du spectromètre d'ALICE, impliquant la mesure de rapport des productions Upsilon et Upsilon' en fonction de l'impulsion transverse de la résonance. Il est montré que cette étude devrait permettre de statuer quand à la formation d'un état déconfiné et d'extraire certaines de ses propriétés.

L'expérience ALICE au LHC va étudier dès 2010 le plasma de quarks et de gluons (QGP), état de la matière dans lequel les quarks et les gluons sont déconfinés. Le travail présenté ici a été effectué au sein de la collaboration ALICE, dans le but de préparer l'analyse des futures données expérimentales. Outre une approche théorique du QGP et de la symétrie chirale, nous y développons trois aspects expérimentaux : le sous-détecteur V0, l'étude des mésons de basses masses et la déconvolution. Tout d'abord, nous détaillons les mesures de luminosité et de multiplicité réalisables avec le V0. Ensuite, nous développons l'étude des dimuons dans le spectromètre à muons. Nous nous concentrons en particulier sur les mésons de basses masses : le rho, le omega et le phi. Enfin, nous présentons une façon d'améliorer les données du spectromètre : la déconvolution de Richardson-Lucy.

We investigate charmonium production in the hot medium created by heavy-ion collisions by setting up a framework in which in-medium charmonium properties are constrained by thermal lattice QCD (lQCD) and subsequently implemented into kinetic approaches. A Boltzmann transport equation is employed to describe the time evolution of the charmonium phase space distribution with the loss and gain term accounting for charmonium dissociation and regeneration (from charm quarks), respectively. The momentum dependence of the charmonium dissociation rate is worked out. The dominant process for in-medium charmonium regeneration is found to be a 3-to-2 process. Its corresponding regeneration rates from different input charmquark momentum spectra are evaluated. Experimental data on J/[psi] production at CERN-SPS and BNL-RHIC are compared with our numerical results in terms of both rapidity-dependent inclusive yields and transverse momentum (pt) spectra. Within current uncertainties from (interpreting) lQCD data and from input charm-quark spectra the centrality dependence of J/[psi] production at SPS and RHIC (for both mid-and forward rapidity) is reasonably well reproduced. The J/[psi] pt data are shown to have a discriminating power for in-medium charmonium properties as inferred from different interpretations of lQCD results.

Cette thèse s'articule autour de la compréhension du mécanisme de brisure spontanée de symétrie électrofaible dans l'expérience ATLAS au LHC, à travers deux thématiques complémentaires : la recherche du boson de Higgs dans le canal H->gamma gamma et une recherche de dimensions supplémentaires dans le secteur des gluons. Par ailleurs, les tests de l'électronique du calorimètre électromagnétique ont permis de valider la conception des cartes contrôleur et maître SPAC, dont la responsabilité était liée au LPNHE.<br /><br />Pour la recherche du Higgs dans le canal H->gamma gamma, l'utilisation de données de simulation complète du détecteur a permis de calculer de façon précise la résolution en masse du système diphotons. Concernant le bruit de fond de jets, une étude a été faite avec des variables discriminantes afin d'obtenir, pour une efficacité de 80 % d'identification des photons, un pouvoir de réjection des jets de l'ordre de 7000. Grâce aux progrès théoriques récents, le signal et le bruit de fond ont pu être étudiés à un ordre supérieur du développement perturbatif, ce qui augmente les sections efficaces. Le potentiel de découverte profite de cette augmentation des sections efficaces et augmente de 50 % par rapport à la même analyse faite au niveau fondamental (LO). Enfin, une nouvelle analyse utilisant une méthode de maximum de vraisemblance permet d'améliorer de l'ordre de 40 % le potentiel de découverte par rapport à notre propre analyse classique. Finalement, le boson de Higgs peut maintenant être découvert dans ce canal pour une luminosité intégrée de 10 fb^(-1) pour un Higgs à 120 GeV/c^2<br /><br />Par ailleurs, le problème de naturalité de la masse du Higgs peut être résolu par l'introduction de dimensions supplémentaires dans lesquelles les gluons peuvent se propager. Nous avons montré qu'il était possible de découvrir l'existence de dimensions supplémentaires jusqu'à une échelle de compactification de 15 TeV.