Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 65-70).

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 190-199).

One of the primary goals of the CERN Large Hadron Collider is to search for new physics. Many such searches have been carried out, in particular searches for supersymmetry, yet no new physics beyond the Standard Model has been found. With a large number of free parameters introduced by frameworks such as supersymmetry, it can be difficult to interpret the null results of searches. The first analysis presented in this thesis attempts to tackle this difficulty head-on, and gives a summary of the constraints from the Run-1 ATLAS searches. A combination of 22 searches were used, with integrated luminosities of up to 20.3 inverse femtobarns of 7 and 8 TeV data. The results are interpreted in the context of the 19-dimensional phenomenological MSSM, and are presented in terms of the masses of supersymmetric particles. Constraints from dark matter, heavy flavour and precision electroweak measurements were incorporated, and results are also interpreted in terms of these observables. Properties of models missed by the Run-1 searches are also shown. The second analysis presented in this thesis documents a direct search for new physics, using 18.2 inverse femtobarns of 13 TeV data collected during 2015 and 2016 by the ATLAS detector. The search targets final states with large jet multiplicity (at least 7 to at least 10 jets), which can arise from the pair production of gluinos decaying via a cascade. Further requirements are imposed on the sum of masses of reclustered large-radius jets. No evidence for new physics is found, and the results are interpreted in both a model-independent way and in terms of two simplified supersymmetric models, one of which was inspired by the results of the first study. Limits on the gluino mass of up to 1600 GeV are set at the 95 % confidence level, extending previous limits.

xviii, 124 p. : ill. (some col.) / This dissertation discusses three topics on scenarios beyond the Standard Model. Topic one is the effects from a fourth generation of quarks and leptons on electroweak baryogenesis in the early universe. The Standard Model is incapable of electroweak baryogenesis due to an insufficiently strong enough electroweak phase transition (EWPT) as well as insufficient CP violation. We show that the presence of heavy fourth generation fermions solves the first problem but requires additional bosons to be included to stabilize the electroweak vacuum. Introducing supersymmetric partners of the heavy fermions, we find that the EWPT can be made strong enough and new sources of CP violation are present. Topic two relates to the lepton avor problem in supersymmetry. In the Minimal Supersymmetric Standard Model (MSSM), the off-diagonal elements in the slepton mass matrix must be suppressed at the 10-3 level to avoid experimental bounds from lepton avor changing processes. This dissertation shows that an enlarged R-parity can alleviate the lepton avor problem. An analysis of all sensitive parameters was performed in the mass range below 1 TeV, and we find that slepton maximal mixing is possible without violating bounds from the lepton avor changing processes: μ [arrow right] eγ; μ [arrow right] e conversion, and μ [arrow right] 3e. Topic three is the collider phenomenology of quirky dark matter. In this model, quirks are particles that are gauged under the electroweak group, as well as a \dark" color SU (2) group. The hadronization scale of this color group is well below the quirk masses. As a result, the dark color strings never break. Quirk and anti-quirk pairs can be produced at the LHC. Once produced, they immediately form a bound state of high angular momentum. The quirk pair rapidly shed angular momentum by emitting soft radiation before they annihilate into observable signals. This dissertation presents the decay branching ratios of quirkonia where quirks obtain their masses through electroweak symmetry breaking. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Dr. Davison Soper: Chair; Dr. Graham Kribs: Advisor; Dr. Ray Frey: Member; Dr. Michael Kellman: Outside Member

Cette thèse concerne deux sujets différents: une étude d'une classe de modèles matriciels qui sont pertinents pour l'holographie, et le calcul d'observables dans une théorie superconforme N = 2 grâce à la technique de la localisation supersymétrique. Le premier sujet traite de modèles matriciels avec symétrie U(N)xO(D) qui ont été introduits récemment. Dans ces modèles, appelés modèles de matrices-vecteurs, il a été montré qu'il est possible de définir une limite de grand D qui conduit à un développement en diagrammes planaires resommable. De plus, ils contiennent des champs et des symétries inspirés de la théorie des cordes et il a été montré qu'un de ces modèles présente les mêmes propriétés physiques que le modèle SYK, dont la connexion avec l'holographie est bien connue. Dans cettethèse, l'étude de ces modèles matriciels est étendue en considérant plusieurs généralisations de la littérature existante. L'étude de modèles avec des termes d'interaction multi-traces et avec une symétrie réduite, et le calcul des observables multi-traces, sont considerés. De plus, plusieurs problèmes concernant la construction de modèles sont pris en considération. Enfin, une analyse approfondie des modèles de matrices-vecteurs fermioniques avec des termes d'interaction quartique est effectuée. Dans le cadre de la localisation supersymétrique, la seconde partie de la thèse se concentre sur le calcul des observables dans la QCD superconforme N = 2 (SCQCD) en 4 dimensions avec symétrie de jauge SU(N). Pour commencer, les résultats connus concernant le calcul de corrélateurs d'opérateurs chiraux et les valeurs moyennes de boucles de Wilson circulaires en utilisant la technique de la localisation supersymétrique sont présentés. La contribution originale de cette partie concerne le calcul de corrélateurs entre opérateurs chiraux et boucles de Wilson circulaires. Le calcul est organisé comme suit: d'abord, les observables sont calculées à travers le modèle matriciel résultant de la procédure de localisation. Ensuite, les résultats du modèle matriciel sont testés par rapport au calcul utilisant la théorie quntique des champs perturbative. Ce calcul esteffectué en prenant la différence entre l'observable calculée dans N = 2 SCQCD et la même observable calculée dans N = 4 super Yang-Mills. Ceci réduit considérablement le nombre de diagrammes de Feynman qui contribuent au corrélateur, ce qui permet d'effectuer des contrôles perturbatifs jusqu'à deux boucles. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Made available in DSpace on 2014-06-11T19:25:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-11Bitstream added on 2014-06-13T19:32:38Z : No. of bitstreams: 1 azevedo_tac_me_ift.pdf: 373974 bytes, checksum: 6a2336bc24ee4aed68e9d75a6f8dc9d1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A correspondência AdS/CFT, da forma como foi conjecturada por Maldacena, sugere uma equivalência notável entre duas teorias aparentemente não relacionadas, quais sejam uma teoria de supercordas tipo IIB em um background AdS5 × S5 e uma teoria de super Yang–Mills (SYM) em quatro dimensões maximalmente supersimétrica(N = 4). Nesta dissertação, estudamos a relação entre o espectro da teoria de supergravidade tipo IIB em AdS5 × S5 (limite de baixas energias da teoria de supercordas mencionada acima) e a família de operadores invariantes degauge em N = 4 SYM descrita em [P. Howe, P. West, Int. J. Mod. Phys. A 14 (1999) 2659] através do uso de um superespaço harmônico, tendo como base principal o artigo [P. Heslop, P. Howe, Phys. Lett. B 502 (2001) 259]. Fazemos ainda uma revisão do formalismo de cosets, que é amplamente utilizado neste trabalho / The AdS/CFT correspondence, as conjectured by Maldacena, suggests a remarkable equivalence between two apparently unrelated theories, namely a type IIB superstring theory on an AdS5 ×S5 background and a maximally supersymmetric (N = 4) super Yang–Mills (SYM) theory in four dimensions. In this dissertation, we study the relation between the spectrum of the type IIB supergravity theory on AdS5 × S5 (low-energy limit of the superstring theory mentioned above) and the family of gauge-invariant operators inN = 4 SYM described in [P. Howe, P. West, Int. J. Mod. Phys. A 14 (1999) 2659] by making use of a harmonic superspace, mostly based on [P. Heslop, P. Howe, Phys. Lett.B502 (2001) 259]. Moreover, we review the coset space formalism, which is largely used in the present work

This thesis is divided into three main parts. In the first of these (comprising chapters 1 and 2) we present the physical context of the research and cover the basic geometric background we will need to use throughout the rest of this thesis. In the second part (comprising chapters 3 to 5) we motivate and develop the strong homogeneity theorem for supergravity backgrounds. We go on to prove it directly for a number of top-dimensional Poincaré supergravities and furthermore demonstrate how it also generically applies to dimensional reductions of those theories. In the third part (comprising chapters 6 and 7) we show how further specialising to the case of symmetric backgrounds allows us to compute complete classifications of such backgrounds. We demonstrate this by classifying all symmetric type IIB supergravity backgrounds. Next we apply an algorithm for computing the supersymmetry of symmetric backgrounds and use this to classify all supersymmetric symmetric M-theory backgrounds.

Orientador: Nathan Jacob Berkovits / Coorientador: Abraham Hirsz Zimerman / Banca: Andrei Mikhailov / Banca: Nelson Braga / Banca: Victor Rivelles / Banca: Vladimir Pershin / Resumo: Primeiro vamos dar uma breve revisão sobre o artigo de Nekrasov " Lectures on curved beta-gamma systems, pure spinors, and anomalies", a fim de mostrar que o formalismo de espinor puro é livre de anomalia quando a origem é removido do espaço espinor puro. Desta forma, damos uma nova proposta para os operadores de imagem no formalismo de espinor puro mínimo. Nós calculamos amplitudes de espalhamento a nível de árvore, realizando a integração no espaço espinor puro como uma integral de Cauchy tipo multidimensional. A amplitude é escrita em termos de variáveis do espaço de espinor puro projetivo, o que é muito útil na hora de relacionar rigorosamente as versões mínima e não mínima do formalismo de espinor puro. A linguagem natural para relacionar esses formalismos é o isomorfismo de Cech-Dolbeault. Além disso, o cociclo de Dolbeault correspondente à amplitude de espalhamento a nível de árvore deve ser avaliada no espaço compacto SO(10)/SU(5) em vez de tudo o espaço de espinor puro, o que significa que a origem é removido neste espaço. Nós também obtimos uma relação entre a função de Green para um campo escalar sem massa em dez dimensões e as amplitude de espalhamento a nível de árvore. Os fatores globais constantes nas amplitudes de espalhamento são muito importante, porque eles precisam satisfazer as condições de unitariedade e S-dualidade [66]. Estes coeficientes não tinham sido computados no formalismo espinor puro, devido à dificuldade para resolver as integrais no espaço de espinores puro. Nós calculamos estas integrais usando o formalismo de espinor puro não mínimo. Assim, encontramos os coeficientes das amplitudes de um e dois-"loop" para quatro pontos sem massa. Contrastando com as dificuldades matemáticas no formalismo RNS, em que o desconhecimento das normalizações... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: First, we give a brief review about the Nekrasov's paper "Lectures on curved betagamma systems, pure spinors, and anomalies" in order to show the pure spinor formalism is anomaly free when the origin is removed from the pure spinor space. In this way we give a new proposal for the "picture lowering" operators in the minimal pure spinor formalism. We compute the tree level scattering amplitude by performing the integration over the pure spinor space as a multidimensional Cauchy-type integral. The amplitude is written in terms of the projective pure spinor variables, which turns out to be useful to relate rigorously the minimal and non-minimal versions of the pure spinor formalism. The natural language for relating these formalisms is the Cech-Dolbeault isomorphism. Moreover, the Dolbeault cocycle corresponding to the three-level scattering amplitude must be evaluated in SO(10)/SU(5) instead of the whole pure spinor space, which means that the origin is removed from this space. We also relate the Green's function for the massless scalar field in ten dimensions to the tree-level scattering amplitude and comment about the scattering amplitude at higher orders. The overall constan factors in the scattering amplitudes are very important because they need to satisfy the unitarity and S-duality conditions [66]. These coefficients have not been computed in the pure spinor formalism due to the difficulty to solve the integrals on the pure spinors space. We compute these integrals by using the non-minimal pure spinor formalism. So, we find the coefficients of the massless one and two-loop four-point amplitude from first principles. Contrasting with the mathematical difficulties in the RNS formalism where unknown normalizations of chiral determinant formulæ force the two-loop coefficient to be... (Complete abstract click electronic access below) / Doutor

Este trabalho tem o objetivo de rever a obtenção das soluções do tipo brana em supergravidade e contém uma dedução detalhada das soluções extrema e negra. A fim de motivar algumas escolhas feitas ao longo do cálculo, o trabalho inclui uma breve revisão dos conceitos advindos da teoria de cordas e supersimetria. Esta revisão nos permitirá ainda relacionar as soluções da supergravidade com as branas da teoria de cordas e tecer considerações sobre o papel desta relação na dualidade entre teoria de calibre e gravitação. / This work intends to review the brane solutions of supergravity and contains a datailed deduction of the extremal and black solutions. In order to provide some motivations to the choices through the calculation, this work includes a brief review of some concepts from string theory and supersymmetry. This review will enable us to relate the supergravity solutions to string theory\'s branes and to make considerations about the role of this relationship in the duality between gauge and gravity theories.

Apresentamos uma revisão dos elementos básicos do estudo da teoria clássica das supercordas em backgrounds planos e curvos, dando ênfase ao caso importante em que o background e a variedade AdS5 S5. Nós inclumos um estudo da corda bosonica para revisarmos alguns conceitos básicos da teoria de campos conforme em duas dimensões. Em seguida estudamos a teoria das supercordas em um espaço plano onde apresentamos uma introdução pedagógica ao formalismo de espinores puros. A ultima parte e dedicada a generalização da ação de Green-Schwarz para o caso de AdS5 S5 e uma apresentação do modelo sigma do formalismo de espinores puros no mesmo background. / We present a review of the basic elements of the study of classical superstring theory in at and curved backgrounds, giving emphasis to the very important case of the AdS5S5 background. We include a study of the bosonic string to review some basic concepts of two dimensional conformal eld theory. We then move on to the superstring in at space where we present a pedagogical introduction to the pure spinor formalism of superstrings. The last part is devoted to the generalization of the Green-Schwarz action to AdS5 S5 and a presentation of the pure spinor sigma model in the same background.