Orientador: Marcelo Moraes Guzzo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T10:34:02Z (GMT). No. of bitstreams: 1 Jurkovich_HeitordoAmaral_M.pdf: 1327191 bytes, checksum: 56f02396f6172fcf091b0c18db27bd7a (MD5) Previous issue date: 2014 / Resumo: Nessa dissertação foi estudada a quebra espontânea de simetria desde suas bases mais fundamentais. A quebra espontânea de simetria e o único mecanismo conhecido capaz de gerar massas a uma teoria, preservando as simetrias e sendo renormalizável. Tal processo ocorre quando se define um setor escalar para uma teoria com uma certa simetria e se quebra os geradores dessa simetria, criando bosons de Goldstone no caso de simetrias globais e campos de gauge massivos, no caso de simetrias locais. Nessa dissertação começamos o estudo de quebra espontânea de simetria com um estudo de Teoria de Grupos, que e fundamental para o entendimento da mesma seguido por um estudo em simetrias nas lagrangianas, ou seja, como gerar uma lagrangiana invariante por um dado grupo, local ou global; depois estudamos o Teorema de Goldstone e por m aplicamos a quebra espontânea de simetria para diversos modelos, entre eles o campo escalar, campo escalar complexo com simetria global, campo escalar complexo com simetria local, modelo padrão. Depois fazemos um estudo em uma das extensões do modelo padrão, o modelo SU(5) e aplicamos a quebra espontânea de simetria em tal modelo. No m mostramos como a abordagem de minimização de um potencial clássico e valida, pois contribuições quântica são análogas a uma energia de ponto zero ao potencial efetivo / Abstract: A detailed study of the spontaneous symmetry breaking since its fundamental basis is done. The spontaneous symmetry breaking is the only know mechanism capable of generating masses to a theory still preserving its symmetry and being renormalizable. Such process occurs when one defines a scalar sector to a certain theory with a symmetry and then break the generators of this symmetry, creating Goldstone bosons in the case of global symmetries and massive gauge fields in the case of local symmetries. We start this dissertation studying Group Theory, which is fundamental to the understanding of spontaneous symmetry breaking. Then we study local and global symmetries of the lagrangian, Goldstone Theorem, then spontaneous symmetry breaking to several models, including the scalar theory, complex scalar theory with global and local symmetries and the standard model. Then we make a study in one of the standard model extensions, the SU(5) model and we applied spontaneous symmetry breaking to this model. In the end we show that the approach of minimizing que classical potential is valid because quantum contributions are analogous to a zero point energy to the effective potential / Mestrado / Física / Mestre em Física

No presente trabalho estudamos duas variações do problema de empacotamento de itens retangulares idênticos, permitindo rotações de 90 graus, em um poliedro. Uma variação consiste em encontrar a maior quantidade de itens retangulares idênticos que podem ser empacotados em um poliedro. A outra consiste em encontrar o poliedro de um determinado tipo com menor área para empacotar uma quantidade fixa de itens retangulares idênticos. Desenvolvemos restrições de eliminação de simetrias para estes problemas, o que tornou a resolução dos mesmos mais eficiente, por métodos do tipo branch-&-bound. Estudamos também o problema de corte no qual há uma determinada demanda (de itens) a ser cortada e um conjunto de objetos disponíveis. Desejamos satisfazer a demanda minimizando o custo dos objetos utilizados e, dentre as diferentes possibilidades de se fazer isso, desejamos aquela que maximize as sobras aproveitáveis. De forma geral, sobras aproveitáveis podem ser entendidas como regiões retangulares de um objeto que possuem altura e largura iguais ou superiores a de um item de referência e representam sobras do processo de corte que podem se tornar objetos e serem reaproveitadas em um novo procedimento de corte. Apresentamos modelos de otimização em dois níveis para duas variações do problema de corte com sobras aproveitáveis a saber: o problema de corte de itens retangulares em dois estágios e o problema de corte de itens retangulares não guilhotinado. Como formas de resolver os modelos propostos, apresentamos reformulações destes modelos de programação em dois níveis em modelos de programação inteira mista. Lidamos também com uma variação do problema de corte com sobras aproveitáveis considerando a minimização da quantidade de sobras. Aplicamos restrições de eliminação de simetrias aos modelos desenvolvidos para o problema de corte de itens retangulares com sobras aproveitáveis, a fim de resolver instâncias maiores, e desenvolvemos uma estratégia de solução alternativa para os modelos. Os modelos desenvolvidos foram implementados computacionalmente e fomos capazes de resolver instâncias pequenas dos problemas em questão. / In this work we study two variations of the packing problem where identical rectangular items must be packed into a polyhedron. One of the variations consists in finding the largest amount of rectangular items that can fit in a polyhedron. The other one consists in finding a minimal area polyhedron of a certain type that packs a set of rectangular identical items. We present some symmetry-breaking constraints that reduce the computational effort in solving those problems through a branch-&-bound method. We also studied the cutting stock problem where there are some items to be cut from a set of rectangular objects and we need to satisfy the demand of items to be cut minimizing the cost of the used objects and, among the different ways of doing this, we want that which maximize the usable leftovers. Loosely speaking,usable leftovers can be understood as rectangular regions in an object that has the width and the height greater than or equal to the ones of a reference item. These leftovers can be seen as leftovers from a cutting process that will become items in a new cutting process. We present bilevel programming models to two variations of this problem with usable leftovers: the two-stage cutting stock problem of rectangular items and the non-guillotine cutting stock problem of rectangular items. In order to solve the proposed models we present also MIP reformulations of these bilevel programming problem models. We also developed some symmetry breaking constraints in order to accelerate the solving process of those models. The developed models were computationally programmed and we were able to solve small instances of the proposed problems

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21598号 / 理博第4505号 / 新制||理||1647(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 小野 輝男, 教授 吉村 一良, 教授 島川 祐一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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The Standard Model of particle physics is the best existing theory for describing the interactions between elementary particles. Even though the Standard Model has been confirmed in many experiments, there remain unanswered questions. One of the main questions is how fermions and most gauge bosons get masses; the Standard Model begins with them as massless. The Higgs effect is a mechanism to explain how fermions and several gauge bosons do get masses in the Standard Model. The corresponding Higgs boson is the only particle that has not yet been detected. This Thesis gives a complete review of the Higgs effect and Higgs related topics. It starts with theoretical basics and develops the theory of the Higgs effect within the electroweak section of the Standard Model. The discussion then considers the topics of radiative corrections and the effect of the Higgs boson as a virtual particle, concentrating on the example of the rho-parameter. In addition, experimental and theoretical constraints for the Higgs mass M_H will be given with special emphasis on the Hierarchy Problem which leads to a physically unacceptable Higgs mass when using high energies (of the Grand Unification scale) as a cutoff for the radiative corrections. Furthermore experimental attempts to detect the Higgs boson at LEP2, TEVATRON and LHC will be described and the different decay channels discussed. Finally, alternative theoretical models beyond the Standard Model are motivated and presented, such as supersymmetry, a vectorlike Standard Model and a possible relation between the Higgs and the Inflaton of Cosmology.

The scattering of electroweak gauge bosons is closely connected to the electroweak gauge symmetry and its spontaneous breaking through the Brout-Englert-Higgs mechanism. Since it contains triple and quartic gauge boson vertices, the measurement of this scattering process allows to probe the self-interactions of weak bosons. The contribution of the Higgs boson to the weak boson scattering amplitude ensures unitarity of the scattering matrix. Therefore, the scattering of massive electroweak gauge bosons is sensitive to deviations from the Standard Model prescription of the electroweak interaction and of the properties of the Higgs boson. At the Large Hadron Collider (LHC), the scattering of massive electroweak gauge bosons is accessible through the measurement of purely electroweak production of two jets and two gauge bosons. No such process has been observed before. Being the channel with the least amount of background from QCD-mediated production of the same final state, the most promising channel for the first measurement of a process containing massive electroweak gauge boson scattering is the one with two like-charge W bosons and two jets in the final state. This thesis presents the first measurement of electroweak production of two jets and two identically charged W bosons, which yields the first observation of a process with contributions from quartic gauge interactions of massive electroweak gauge bosons. An overview of the most important issues in Monte Carlo simulation of vector boson scattering processes with current Monte Carlo generators is given in this work. The measurement of the final state of two jets and two leptonically decaying same-charge W bosons is conducted based on proton-proton collision data with a center-of-mass energy of √s = 8 TeV, taken in 2012 with the ATLAS experiment at the LHC. The cross section of electroweak production of two jets and two like-charge W bosons is measured with a significance of 3.6 standard deviations to be σ(W± W±jj−EW[fiducial]) = 1.3 ± 0.4(stat.) ± 0.2(syst.) fb in a fiducial phase space region selected to enhance the contribution from W W scattering. The measurement is compatible with the Standard Model prediction of σ(W±W± jj−EW[fiducial]) = 0.95 ± 0.06 fb. Based on this measurement, limits on anomalous quartic gauge couplings are derived. The effect of anomalous quartic gauge couplings is simulated within the framework of an effective chiral Lagrangian unitarized with the K-matrix method. The limits for the anomalous coupling parameters α4 and α5 are found to be −0.14 < α4 < 0.16 and −0.23 < α5 < 0.24 at 95 % confidence level. Furthermore, the prospects for the measurement of the electroweak production of two same-charge W bosons and two jets within the Standard Model and with additional doubly charged resonances after the upgrade of the ATLAS detector and the LHC are investigated. For a high-luminosity LHC with a center-of-mass energy of √s = 14 TeV, the significance of the measurement with an integrated luminosity of 3000 fb^−1 is estimated to be 18.7 standard deviations. It can be improved by 30 % by extending the inner tracking detector of the atlas experiment up to an absolute pseudorapidity of |η| = 4.0.

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Comment les cellules établissent leurs formes et organisations internes est un problème biologique fondamental. Au cours de cette thèse, j’ai étudié le développement de la forme cellulaire et de la polarité chez la cellule de levure fissipare. Ces études sont fondées sur l’exploration de la façon dont les petites spores symétriques de levures se développent et s’organisent pour briser la symétrie pour la définition de leur tout premier axe de polarité. Dans une première partie, j’ai étudié les couplages entre la mécanique de surface de la paroi cellulaire des spores et la stabilité de domaines de polarité de Cdc42 qui contrôlent les aspects spatio-temporelles de la brisure de symétrie de ces spores. Dans une seconde partie, j’ai étudié les mécanismes par lesquels ces domaines de polarité contrôlent leur taille et l'adapte à la géométrie de la cellule, un processus vraisemblablement pertinents pour comprendre comment des domaines fonctionnels corticaux s’adaptent à la taille des cellules. Globalement, ces nouvelles recherches focalisant sur la façon dont les cellules développent dynamiquement leur forme et polarité de novo, permettent de mettre en évidence des couplages complexes dans la morphogenèse qui ne peuvent pas être testés en regardant les cellules à « l’état stationnaire» ou avec des outils génétiques. / How cells establish their proper shapes and organization is a fundamental biological problem. In this thesis, I investigated the dynamic development of cellular form and polarity in the rod-shape fission yeast cell. These studies are based on monitoring how small symmetric fission yeast spores grow and self-organize to break symmetry for the definition of their very first polarity axis. In a first part, I studied interplays between surface mechanics of the spore cell wall and the stability of Cdc42-based polarity domains which control spatio-temporal aspects of spore symmetry breaking. In a second part, I studied mechanisms by which these polarity domains control their width and adapt it to cell surface geometry, a process likely relevant to understand how functional cortical domains scale to cell size. Overall these novel investigations focusing on how cells dynamically develop their form and polarity de novo highlight complex feedbacks in morphogenesis that cannot be evidenced by looking at cells at “steady state” or with genetics.