In this thesis, various fermion-boson strong interaction potentials are determined as functions of the basic fermion-boson trilinear vertex function. Working in Fock space, we note that the fermion-boson trilinear interaction does not explicitly involve physical particles. We develop a transformation, called the dressing transformation, which acts on the fundamental particle creators and annihilators. They are transformed into physical particle operators, and the invariance properties and commutation relations of the theory are preserved. A precise technique for perturbatively determining the dressing transformation is formulated, and is applied to some simple models in field theory. The dressing transformation makes explicit the physical particle interactions implicit in the original trilinear interaction. When applied to the nucleon-pion trilinear interaction, we find a nucleon mass renormalization, a nucleon-pion scattering term, and a nucleon-nucleon scattering term present in the second-order dressed Hamiltonian. Using the NN7C vertex function derived from the Cloudy Bag Model, the nucleon-nucleon coordinate space potential can be calculated. We discover that providing the two nucleons are separated by a distance greater than twice the bag radius, the potential between them is given by the one pion exchange potential modified in strength by a function of the bag radius. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Este trabalho apresenta os resultados da primeira medida da secao de choque de producao W± e± utilizando dados de colisoes proton-proton com energia de centro de massa s = 13 TeV pelo detector ATLAS em dois regimes diferentes de operacao do Large Hadron Collider (LHC): um perodo de baixa luminosidade em que foram acumulados 81 pb1 de dados e que permitiram medir a secao de choque fiducial e total da producao de bosons W+ e W na regiao inclusiva (regiao de massa transversa acima de 50 GeV, abrangendo o pico de massa transversa do boson W) e um perodo de alta luminosidade em que foi obtido 76,6 fb1 de dados tornando acessvel a medida da secao de choque fiducial de producao de bosons W+ e W na regiao de alta massa transversa (regiao de massa transversa entre 130 GeV e 2,5 TeV). As secoes de choque medidas e as distribuicoes cinematicas referentes a energia transversa faltante (ETmiss ), massa transversa do boson W (mTW), pseudorapidez (), momento transverso (pTe) do eletron decorrente do decaimento do W e a diferenca entre o angulo azimutal () do eletron e da ETmiss sao consistentes com previsoes teoricas obtidas em NLO e normalizadas em NNLO, considerando-se as incertezas sistematicas, estatsticas e na luminosidade. / This work presents the results of the first W± e± production cross section measurements in the proton-proton collisions at the center of mass energy of s = 13 TeV obtained with the ATLAS detector in two different operation regimes: a low luminosity period when 81pb1 of data was accumulated allowing the measurement of the fiducial and total production cross section of W+ and W bosons in the inclusive region (region of transverse mass above 50 GeV, covering the transverse mass peak of the W boson) and a high luminosity period when 76,6 fb1 made accessible the high W boson transverse mass region (between 130 GeV and 2.5 TeV), allowing the measurement of the fiducial cross section of W+ and W boson production. The measured cross sections and the kinematic distributions for the missing transverse energy, (ETmiss), W boson transverse mass (mTW), the pseudorapidity (), the transverse momentum (pTe) of the electron originated from the W boson decay as well as the azimuthal angle difference () between the electron and the ETmiss are consistent with the theoretical predictions obtained at NLO and normalized to NNLO, considering the systematic, statistical and luminosity uncertainties.

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Made available in DSpace on 2018-07-27T18:26:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-17. Added 1 bitstream(s) on 2018-07-27T18:30:16Z : No. of bitstreams: 1 000866736.pdf: 1452961 bytes, checksum: 319c3fa13bbe5e0dc4754274971c2c02 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Consideramos o decaimento do Higgs violando sabor leptônico h→ 'tau' 'mü' no contexto de teorias efetivas. O CMS divulgou recentemente um excesso de eventos de 2,5 'sigma' neste canal. O operador responsável por este processo, no entanto, está em muitos casos correlacionado com operadores de dipolo, que já têm fortes restrições experimentais. Exploramos então em que casos é possível de se obter um operador de violação de sabor grande o suficiente para ser visto em decaimentos do Higgs no LHC, porém ainda respeitando os limites encontrados em decaimentos radiativos de léptons. Apresentamos também dois modelos, um do tipo Higgs Composto e outro do tipo Higgs Portal, mostrando como o processo h→ 'tau' 'mü' surge em cada um deles. Caso o sinal do CMS seja confirmado, o segundo modelo será favorecido, enquanto é improvável que o primeiro consiga o explicar / We consider the Higgs Lepton Flavor Violating decay h→ 'tau' 'mü' in the framework of effective theories, on which CMS reported a 2.5 σ excess of events. The operator that is responsible for this process, however, is in many models correlated to dipole operators that are already under stringent experimental constraints. We then explore in which cases it is possible to obtain a flavor violating operator that is big enough to be seen in Higgs decays at the LHC, while still respecting the leptonic radiative decay bounds. We also present two models, a simplified Composite Higgs model and a Higgs Portal model, showing how the process h→ 'tau' 'mü' is generated in each of them. We find that if the CMS signal is confirmed, the second model is favored, while it is unlikely that the first model will be able to explain it

Orientador: Vicente Pleitez. / Doutor

La découverte d'une particule similaire au boson de Higgs, dernière pièce manquante du Modèle Standard (MS) de la physique des particules élémentaires, est en voie d'être confirmée par les expériences CMS et ATLAS du Large Hadron Collider du CERN. Cependant, il n'est pour le moment pas encore établit que les caractéristiques de la particule observée correspondent aux prédictions du MS. Cela, associé à d'autres observations (Matière Noire,...), motive l'analyse des extensions supersymétriques du MS comme le NMSSM. Nous étudions dans cette thèse la solution au problème de la hiérarchie des échelles d'énergie dans le NMSSM, lié aux divergences quadratiques de la masse du boson de Higgs, ainsi que la phénoménologie du NMSSM avec une brisure de la supersymétrie par interactions de jauge en tenant compte des dernières données du LHC. Enfin, nous détaillons les développements des codes de NMSSMTools effectués au cours de cette thèse~: l'introduction de Chaînes de Markov, le calcul du Fine Tuning, le calcul des cascades de désintégrations des partenaires supersymétriques en particules du MS et l'implémentation du NMSSM général. / The discovery of a particle similar to the Higgs boson predicted by the Standard Model (SM) of particle physics has been confirmed by the experiments CMS and ATLAS of the Large Hadron Collider at the CERN. However, it is not yet clear that the properties of this particle are those predicted by the SM. This, in addition with several other observations (Dark Matter,...), is a motivation for analysing supersymmetric extensions of the SM, as the NMSSM. We study in this thesis the solution of the Hierarchy problem in the NMSSM, linked with the quadratic divergences in the Higgs sector, and also the phenomenology of the NMSSM with gauge mediation supersymmetry breaking in the light of the latest data from the LHC. Finally, we present the developments made in the codes of the package NMSSMTools, featuring Monte Carlo Markov Chain methods, Fine Tuning calculus, the calculus of supersymmetric particle's cascade decays and the implementation of the general NMSSM.

Orientador: Ricardo D'Elia Matheus / Banca: Oscar José Pinto Eboli / Banca: Rogério Rosenfeld / Resumo: Consideramos o decaimento do Higgs violando sabor leptônico h→ 'tau' 'mü' no contexto de teorias efetivas. O CMS divulgou recentemente um excesso de eventos de 2,5 'sigma' neste canal. O operador responsável por este processo, no entanto, está em muitos casos correlacionado com operadores de dipolo, que já têm fortes restrições experimentais. Exploramos então em que casos é possível de se obter um operador de violação de sabor grande o suficiente para ser visto em decaimentos do Higgs no LHC, porém ainda respeitando os limites encontrados em decaimentos radiativos de léptons. Apresentamos também dois modelos, um do tipo Higgs Composto e outro do tipo Higgs Portal, mostrando como o processo h→ 'tau' 'mü' surge em cada um deles. Caso o sinal do CMS seja confirmado, o segundo modelo será favorecido, enquanto é improvável que o primeiro consiga o explicar / Abstract: We consider the Higgs Lepton Flavor Violating decay h→ 'tau' 'mü' in the framework of effective theories, on which CMS reported a 2.5 σ excess of events. The operator that is responsible for this process, however, is in many models correlated to dipole operators that are already under stringent experimental constraints. We then explore in which cases it is possible to obtain a flavor violating operator that is big enough to be seen in Higgs decays at the LHC, while still respecting the leptonic radiative decay bounds. We also present two models, a simplified Composite Higgs model and a Higgs Portal model, showing how the process h→ 'tau' 'mü' is generated in each of them. We find that if the CMS signal is confirmed, the second model is favored, while it is unlikely that the first model will be able to explain it / Mestre

As a phenomenological tool, the Interacting Boson Model (IBM) has been useful and successful in correlating a wide variety of experimental data regarding the collective properties of many nuclei. The original version of the IBM did not distinguish between protons and neutrons and is referred to as the IBM-1. Microscopic investigation of the model revealed the need for explicit proton and neutron degrees of freedom and, thus, the IBM-2 was developed. The net result is a model, the IBM-2, motivated by microscopic theory, which is a boson description of collective features in medium-to-heavy mass even-even nuclei, and which is capable of distinguishing proton and neutron characteristics. A review is presented of the concept of using boson descriptions of many-fermion systems, and the IBM is introduced in a historical context. Next, the use of the IBM-2 as a phenomenological tool is investigated. The model is applied to the even zinc isotopes and the model is found to give a reasonable description of the experimental data. In the phenomenological calculations, the parameters of the IBM-2 Hamiltonian are adjusted until good agreement is obtained with the experimental data. To put the theoretical basis of the IBM-2 on firm ground, it is important to be able to calculate these parameters microscopically. A framework is developed in which such calculations can be performed for non-deformed nuclei. Results are presented for the mercury isotopes and discussed in detail. The calculated parameter values agree for the most part with the values obtained by phenomenological fit but with some exceptions. Similar calculations are performed for the platinum isotopes. The results for these isotopes are then related to the concpet of F-spin multiplets. When the Surface Delta Interaction (SDI) is used, several simplifications can be made in the IBM. In certain schematic situations, the parameters of the IBM-2 Hamiltonian can be related directly to the strength of the SDI. Several interesting results are obtained whose full implication will be investigated in the future. In conclusion, the IBM is discussed in relation with its application to other topics, both within and beyond the realms of nuclear physics. Several appendices are attached in which many algebraic details are shown explicitly. A brief summary is given of the computer codes that have been written in connection with this work.

O objetivo desse trabalho é apresentar e investigar um modelo integrável que descreve o tunelamento de bósons entre três condensados de Bose-Einstein acoplados em linha. Aqui, entendemos como modelo integrável, aquele que tem solução exata pelo método algébrico do Ansatz de Bethe. Inicialmente, verificamos a integrabilidade do modelo através desse método, o que exigiu uma abordagem mais sofisticada do que a usual, para obtenção de todas as quantidades conservadas. Posteriormente, exploramos a quebra da integrabilidade adicionando um termo ao Hamiltoniano. Esta quebra é analisada através dos níveis de energia e da distribuição estatística dos espaçamentos entre energias, cujo histograma gerou uma distribuição do tipo Wigner-Dyson. Estudamos algumas possíveis dinâmicas quânticas do sistema e apresentamos uma configuração esquemática que lembra um transistor. / In this work we present and investigate an integrable model that describes the tunneling of bosons between three coupled aligned Bose-Einstein condensates. Here, integrability means that the model can be exactly solved by the Bethe Ansatz method. Initially we verify the integrability of the model through this method, which requires a more sophisticated approach than usual in order to obtain all conserved quantities. Subsequently, we explore what happens when the integrability is broken by adding a special term to the Hamiltonian. This break is analyzed by means of the energy levels and the statistical energy level spacing distribution, generating a Wigner Dyson distribution. Finally we study the quantum dynamics of the system and present a schematic con guration that resembles a transistor.

Bibliography: leaves 154-158.