In this thesis, we construct two QCD based energy loss models to perform quantitative analysis of jet quenching observables in ultra-relativistic nucleus-nucleus collisions at RHIC and the LHC. We first build up a perturbative QCD based CUJET2.0 jet flavor tomography model that couples the dynamical running coupling DGLV opacity series to bulk data constrained relativistic viscous hydrodynamic backgrounds. It solves the strong heavy quark energy loss puzzle at RHIC and explains the surprising transparency of the quark-gluon plasma (QGP) at the LHC. The observed azimuthal anisotropy of hard leading hadrons requires a path dependent jet-medium coupling in CUJET2.0 that implies physics of nonperturbative origin. To explore the nonperturbative chromo-electric and chromo-magnetic structure of the strongly-coupled QGP through jet probes, we build up a new CUJET3.0 framework that includes in CUJET2.0 both Polyakov loop suppressed semi-QGP chromo-electric charges and emergent chromo-magnetic monopoles in the critical transition regime. CUJET3.0 quantitatively describes the anisotropic hadron suppression at RHIC and the LHC. More significantly, it provides a robust connection between the long wavelength "perfect fluidity'' of the QGP and the short distance jet transport in the QGP. This framework paves the way for ``measuring'' both perturbative and nonperturbative properties of the QGP, and more importantly for probing color confinement through jet quenching.

Ce travail présente la mesure de la section efficace différentielle du boson Z en impulsion transverse (ptz), dans le canal de désintégration electron-positron, avec le détecteur ATLAS au LHC. La mesure utilise 4.64 inverse fb de données de collisions proton-proton, prises en 2011 avec une énergie du centre de masse de 7 TeV. Le résultat est combiné avec une mesure indépendante faite dans le canal muon-antimuon. La mesure est faite jusqu'à ptz = 800 GeV, et a une incertitude typique de 0.5 % pour ptz < 60 GeV, atteignant jusqu'à 5 % vers la fin du spectre. La mesure est comparée avec modèles théoriques et prédictions des générateurs Monte Carlo.

No description available.

Submitted by FERNANDO ENRIQUE SERNA ALGARÍN null (ferse1129@gmail.com) on 2018-01-10T21:52:53Z No. of bitstreams: 1 tese.pdf: 948147 bytes, checksum: 94d535ccc424f5f4201747cae4382d6a (MD5) / Approved for entry into archive by Hellen Sayuri Sato null (hellen@ift.unesp.br) on 2018-01-12T15:54:08Z (GMT) No. of bitstreams: 1 algarin_fcs_dr_ift.pdf: 948147 bytes, checksum: 94d535ccc424f5f4201747cae4382d6a (MD5) / Made available in DSpace on 2018-01-12T15:54:08Z (GMT). No. of bitstreams: 1 algarin_fcs_dr_ift.pdf: 948147 bytes, checksum: 94d535ccc424f5f4201747cae4382d6a (MD5) Previous issue date: 2017-10-02 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Nesta tese empregamos um modelo de interação de contato que preserva simetrias para estudar estrututura hadrônica e matéria de quarks. A interação de contato é uma representação de kernels não perturbativos usados em equações de Dyson-Schwinger e Bethe-Salpeter da Cromodinâmica Quântica (QCD). A ideia básica do modelo está baseada num esquema de subtração que evita passos tradicionais no cálculo de de integrais divergentes que invariavelmente levam a violações de simetrias. Em temperatura zero, as equações de Dyson-Schwinger equation para os propagadores dos quarks u; d; s and c são resolvidas e amplitudes de estado ligado de Bethe-Salpeter, que respeitam a invariância sob translações espaço-temporais e as identidades de Ward-Takahashi associadas com simetrias globais da QCD, são obtidas para calcular as massas e as constantes de decaimento eletrofracas dos mésons pseudoscalares π; K, D e Ds e dos mésons vetorias ρ, K*, D* e Ds*. As predições do modelo estão em bom acordo com dados experimentais e da QCD na rede. Em adição, estendemos o modelo para temperaturas diferentes de zero; neste caso, o problema de violação de simetrias está restrito apenas às partes puramente divergentes porque os termos que dependem das distribuições térmicas são finitas e não requerem regularização. Finalmente, investigamos a dependência com a temperatura das contribuições das flutuações quânticas quark-π e quark-σ aos coeficientes de transporte de viscosidade de cisalhamento η e volumétrica ζ e as suas razões com a densidade de entropia s. As larguras térmicas originárias dessas fluctuações são calculadas com o formalismo de teoria de campos a temperatura finita de tempo real. Para esse cálculo, empregamos os resultados obtidos com as equações de Dyson-Schwinger e Bethe-Salpeter para a dependência com a temperatura das massas dos mésons e as contantes de acoplamento quark-méson. Os resultados para as razões η/s and ζ/s estão em bom acordo com resultados com a literatura obtidos com modelos e técnicas diferentes. Em particular, nossos resultados para η/s possuem um mínimo muito próximo ao limite inferior da conjectura AdS/CFT, η/s = 1/4π. / In thesis, a symmetry-preserving contact interaction model is used to study hadron structure and quark matter. The contact interaction is a representation of nonperturbative kernels used in Dyson-Schwinger and Bethe-Salpeter equations of Quantum Chromodynamics (QCD). The basic idea of the model is based on a subtraction scheme that avoids standard steps in the evaluation of divergent integrals that invariably lead to symmetry violation. At zero temperature, the Dyson-Schwinger equation is solved for the u; d; s and c quark propagators and the boundstate Bethe-Salpeter amplitudes respecting spacetime-translation invariance and the Ward-Green-Takahashi identities associated with global symmetries of QCD are obtained to calculate masses and electroweak decay constants of the pseudoscalar π; K, D and Ds and vector ρ, K*, D*, and Ds* mesons. The predictions of the model are in good agreement with available experimental and lattice QCD data. In addition, we extend the model to nonzero temperature; here, the problem of symmetry violation is associated only with the purely divergent parts because the effects due to the termal distributions are finite and do not need regularization. We compute the temperature dependence of the masses and decay constants of the pseudoscalar mesons considered here. Finally, we have investigated the temperature dependence of the contributions of quark-π and quark-σ quantum fluctuations to the transport coefficients of shear η and bulk ζ viscosities and their ratios to the entropy density s. The quark thermal widths originating those fluctuations are calculated with the formalism of real-time thermal field theory. For these calculations, we have used the results obtained via Dyson-Schwinger and Bethe-Salpeter equations for the temperature dependence of constituent quark and meson masses and quark-meson couplings. The results for the ratios η/s and ζ/s are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for η/s has a minimum very close to the conjectured AdS/CFT lower bound, η/s = 1/4π. / CNPq:140041/2014-1

Nous avons développé une nouvelle approche basée sur les méthodes Monte Carlo par chaînes de Markov pour déterminer les distributions de Partons et quantifier leurs incertitudes expérimentales. L’intérêt principal d’une telle étude repose sur la possibilité de remplacer la minimisation standard avec MINUIT de la fonction χ 2 par des procédures fondées sur les méthodes Statistiques et sur l’inférence Bayésienne en particulier,offrant ainsi une meilleure compréhension de la détermination des distributions de partons. Après avoir examiné ces techniques Monte Carlo par chaînes de Markov, nous introduisons l’algorithme que nous avons choisi de mettre en œuvre, à savoir le Monte Carlo hybride (ou Hamiltonien). Cet algorithme, développé initialement pour la chromodynamique quantique sur réseau, s’avère très intéressant lorsqu’il est appliqué à la détermination des distributions de partons par des analyses globales. Nous avons montré qu’il permet de contourner les difficultés techniques dues à la grande dimensionnalité du problème, en particulier celle relative au taux d’acceptation. L’étude de faisabilité réalisée et présentée dans cette thèse indique que la méthode Monte Carlo par chaînes de Markov peut être appliquée avec succès à l’extraction des distributions de partons et à leurs in-certitudes expérimentales. / We have developed a new approach to determine parton distribution functions and quantify their experimental uncertainties, based on Markov Chain Monte Carlo methods.The main interest devoted to such a study is that we can replace the standard χ 2 MINUIT minimization by procedures grounded on Statistical Methods, and on Bayesian inference in particular, thus offering additional insight into the rich field of PDFs determination.After reviewing these Markov chain Monte Carlo techniques, we introduce the algorithm we have chosen to implement – namely Hybrid (or Hamiltonian) Monte Carlo. This algorithm, initially developed for lattice quantum chromodynamique, turns out to be very interesting when applied to parton distribution functions determination by global analyses ; we have shown that it allows to circumvent the technical difficulties due to the high dimensionality of the problem, in particular concerning the acceptance rate. The feasibility study performed and presented in this thesis, indicates that Markov chain Monte Carlo method can successfully be applied to the extraction of PDFs and of their experimental uncertainties.

This thesis presents the measurement of the differential cross section of Z boson pro-duction in association with jets (Z+jets) in proton-proton collision at the center-of-massenergy of 13 TeV. The data has been recorded with the CMS detector at the LHC duringthe year 2015, corresponding to an integrated luminosity of 2.19 fb −1 .A study of theCMS muon High Level Trigger (HLT) with the data collected in 2016 is also presented.The goal of analysis is to perform a first measurement at 13 TeV of the cross sections ofZ+jets as a function of the jet multiplicity, its dependence on the transverse momentumof the Z boson, the jet kinematic variables (transverse momentum and rapidity), thescalar sum of the jet momenta, and the balance in the transverse momentum betweenthe reconstructed jet recoil and the Z boson. The results are obtained by correctingthe detector effects, and are unfolded to particle level. The measurement are com-pared to four predictions using different approximations: at the leading-order (LO),next-to-leading-order (NLO) and next-to-next-to-leading order (NNLO) accuracy. Thefirst two calculations used M AD G RAPH 5_ A MC@NLO interfaced with PYTHIA 8 for theparton showering and hadronisation, one of which includes matrix elements (MEs) atLO, another includes one-loop corrections (NLO). The third is a fixed-order calculationwith NNLO accuracy for Z+1 jet using the N -jettiness subtraction scheme (N jetti ). Thefourth uses the GENEVA program with an NNLO calculation combined with higher-order resummation.A series of studies on the HLT double muon trigger are also included. Since 2015 theLHC reached higher luminosity, more events are produced inside the CMS detector persecond, which resulted in more challenges for the trigger system. The work presentedincludes the monitoring, validation and the calibration of the muon trigger paths since2016. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Cromodinâmica quântica, Espalhamento / Highly inelastic scattering proton electron in quantum chromodynamics

Nesta tese de doutorado é utilizado o método das Regras de Soma da QCD para estudar a natureza dos novos estados ressonantes do charmonium: Y(3930), Y(4140), X(4350), Y(4260), Y(4360) e Y(4660). Há fortes evidências de que estes estados possuam estruturas hadrônicas não convencionais (ou exóticas) uma vez que as suas respectivas massas e canais de decaimento observados experimentalmente são inconsistentes com o que é esperado para o estado ressonante convencional do charmonium, J/psi. O mesmo fenômeno ocorre no setor do bottomonium, onde os novos estados Yb(10890) e Yb(11020) observados recentemente poderiam indicar a existência de novos estados exóticos do bottomonium. Neste sentido, verifica-se que o estado Y(4140) poderia ser descrito ou por uma estrutura molecular Ds*Ds* (0++) ou mesmo uma mistura entre estados moleculares Ds*Ds* (0++) e D*D* (0++). Já os estados Y(3930) e o X(4350) não podem ser descritos por correntes moleculares D*D* (0++) e Ds*Ds* (1-+), respectivamente. Verifica-se também que a estrutura molecular Psi(2S) f_0(980) (1--) descreve muito bem a massa do estado Y(4660). Uma extensão ao setor do bottomonium indica que o estado molecular Y(2S) f_0(980) é um bom candidato para descrever a estrutura do estado Yb(10890). É feita também uma estimativa para os possíveis estados moleculares formados por mésons D(*) e B(*), que poderão ser observados em futuros experimentos realizados pelo LHC. Um amplo estudo, utilizando o formalismo das Regras de Soma e também da Dupla Razão das Regras de Soma, é feito para calcular as massas dos bárions pesados na QCD. As estimativas para as massas dos bárions com um (Qqq) e com dois (QQq) quarks pesados são um excelente teste para a capacidade do método das regras de soma em prever a massa dos bárions que ainda não foram observados. / In this thesis, the QCD sum rules approach was used to study the nature of the new charmonium resonances: Y(3930), Y(4140), X(4350), Y(4260), Y(4360) and Y(4660). There is a strong evidence that these states have non-conventional (or exotic) hadronic structures since their respective masses and decay channels observed experimentally are inconsistent with what expected for a conventional charmonium state, J/psi. The same phenomenon occurs on the bottomonium sector, where new states like Yb(10890) and Yb(11020) observed recently could indicate the existence of new bottomonium exotic states. In this way, one verifies that the state Y(4140) could be described as a Ds*Ds* (0++) molecular state or even as a mixture of Ds*Ds* (0++) and D*D* (0++) molecular states. For the Y(3930) and X(4350) states, both cannot be described as a D*D* (0++) and Ds*Ds* (1-+), respectively. From a sum rule point of view, the Y(4660) state could be described as a Psi(2s) f_0(980) (1--) molecular state. The extension to the bottomonium sector is done in a straightforward way to demonstrate that the Y(2S) f_0(980) molecular state is a good candidate for describing the structure of the Yb(10890) state. In the following, one estimates the mass of the exotic Bc-like molecular states using QCD Sum Rules - these exotic states would correspond to bound states of D(*) and B(*) mesons. All of these mass predictions could (or not) be checked in a near future experiments at LHC. A large study using the Double Ratio of Sum Rules approach has been evaluated for the study of the heavy baryon masses in QCD. The obtained results for the unobserved heavy baryons, with one (Qqq) and two (QQq) heavy quarks will be an excellent test for the capability of the sum rule approach in predicting their masses.

La these de doctorat intitulee ``Mesure de la diffusion Compton a haute virtualite a HERA II'<p>a ete realisee au sein du service de physique des particules elementaires de l'ULB sous<p>la direction de mon promoteur Laurent Favart<p>et porte sur l'analyse des donnees enregistrees par l'experience H1 situee aupres du collisionneur<p>electron-proton HERA du laboratoire DESY a Hambourg. <p><p>L'analyse presentee concerne l'etude d'un processus diffractif exclusif particulier,<p>le processus de diffusion Compton a haute virtualite ou DVCS (Deeply Virtual Compton Scattering), e p -> e p gamma, qui correspond a <p>la diffusion gamma* p -> gamma p$ d'un photon<p>hautement virtuel par le proton, dans le domaine cinematique 6.5 < Q^2 < 80 GeV2,<p>30 < W < 140 GeV et / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Aux énergies assez hautes, les processus de QCD peuvent être factorisés en une partie dure, qui peut être calculée en utilisant les méthodes perturbatives des diagrammes de Feynman grâce à la petite valeur de la constante de couplage de l'interaction forte, et une partie non-perturbative qui doit être extraite de données expérimentales, modélisées ou calculées avec d'autres méthodes comme par exemple la QCD sur réseau. Cependant la petite valeur de la constante de couplage dans la partie perturbative peut être compensée par des grands logarithmes émergeant de l'annulation de divergences molles ou colinéaires, ou de la présence d'échelles cinématiques multiples. De telles contributions doivent être resommées, ce qui mène à l'équation d'évolution DGLAP aux énergies modérées et aux équations BFKL et B-JIMWLK dans la limite des hautes énergies. Pour les énergies les plus grandes des effets de recombinaison de gluons amènent à la saturation, qui peut être décrite par le formalisme du CGC ou des ondes de choc. Dans cette thèse, nous nous proposons d'étudier certains processus exclusifs en QCD perturbative afin d'obtenir une meilleure description de la factorisation et des effets de resommation et de saturation. Dans un premier temps nous faisons le premier calcul d'une quantité exclusive au premier ordre sous-dominant (NLO) dans le contexte du formalisme des ondes de choc de QCD. Nous calculons l'amplitude NLO pour la production diffractive ouverte d'une paire quark-antiquark, puis nous parvenons à construire une section efficace finie à l'aide de cette amplitude en étudiant la production diffractive exclusive de deux jets vers l'avant. Des analyses précises phénoménologiques et expérimentales de ce processus devraient améliorer notre compréhension de la resommation à haute énergie grâce à la présence d'un Pomeron échangé en diffraction, ce qui est naturellement décrit par la resommation de logarithmes découlant de la divergence molle de la QCD à haute énergie. Notre résultat reste valable quand l'énergie au centre de masse devient proche de l'échelle de saturation ou lorsque la diffraction a lieu sur une cible dense donc il peut être utilisé pour l'étude des effets de saturation. Dans un deuxième temps, nous montrons que l'étude expérimentale de la photoproduction d'un méson léger et d'un photon à énergies modérées devrait constituer un bon moyen d'appréhender les Distributions de Parton Généralisées (GPDs), l'une des généralisations des blocs non perturbatifs en factorisation collinéaire. En principe une telle étude donnerait accès à la fois aux GPDs conservant l'hélicité ou la renversant. Nous donnons des prédictions numériques pour ce processus à JLAB@12GeV. / At high enough energies, QCD processes can be factorized into a hard part, which can be computed by using the smallness of the strong coupling to apply the perturbative Feynman diagram method, and a non-perturbative part which has to be fitted to experimental data, modeled or computed using other tools like for example lattice QCD. However the smallness of the strong coupling in the perturbative part can be compensated by large logarithms which arise from the cancellation of soft or collinear divergences, or by the presence of multiple kinematic scales. Such logarithmically-enhanced contributions must be resummed, leading to the DGLAP evolution at moderate energies and to the BFKL or B-JIMWLK equation in the high energy limit. For the largest energies gluon recombination effects lead to saturation, which can be described in the color glass condensate (CGC) or shockwave formalism. In this thesis, we propose to study several exclusive perturbative QCD processes in order to get a better understanding of factorization, resummation and saturation effects. In the first part we perform the first computation of an exclusive quantity at Next-to-Leading-Order (NLO) accuracy using the QCD shockwave formalism. We calculate the NLO amplitude for the diffractive production of an open quark-antiquark pair, then we manage to construct a finite cross section using this amplitude by studying the exclusive diffractive production of a dijet. Precise phenomenological and experimental analysis of this process should give a great insight on high energy resummation due to the exchange of a Pomeron in diffraction, which is naturally described by the resummation of logarithms emerging from the soft divergences of high energy QCD. Our result holds as the center of mass energy grows towards the saturation scale or for diffraction off a dense target so one could use it to study saturation effects. In the second part we show how the experimental study of the photoproduction of a light meson and a photon at moderate energy should be a good probe for Generalized Parton Distributions (GPDs), one of the generalizations of the non-perturbative building blocks in collinear factorization. In principle such a study would give access to both helicity-conserving and helicity-flip GPDs. We give numerical predictions for this process at JLAB@12GeV.