Nesta tese, apresentamos os resultados do estudo realizado para os modelos -não lineares com simetria O(N) bosônico ou supersimétrico assim como a adição do termo topológico de Wess-Zumino (teoria WZNW). Obtivemos as suas cargas conservadas não locais e a estrutura das álgebras clássicas de parênteses de Dirac correspondentes, utilizando um método gráfico que criamos para realizar estes cálculos nos modelos estudados. / In this thesis, we exhibit the results of the study made for the non linear models with O(N) symmetry, bosonic or supersymmetric as well as with the addition the topological Wess-Zumino term (WZNW theory). We found their non-local conserved charges and the structure of the corresponding c1assical algebras of Dirac brackets, using a graphical method that we created to make these calculations.

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.

A search for supersymmetry is presented based on proton-proton collision events containing identified hadronically decaying top quarks (i.e., events with no identified leptons), and an imbalance EmissT in transverse momentum. The data were collected with the Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 35.9 fb-1. The 84 exclusive search regions are defined in terms of the multiplicity of bottom quark jet and top quark candidates, the missing energy, the scalar sum of jet transverse momenta HT, and the transverse mass variable sensitive to the pair production of heavy particles, each of which decays into an invisible particle MT2. A novel and robust top quark reconstruction algorithm which is based on multivariate approach and is capable of identifying top quarks in the wide spectrum of top quark transverse momentum is developed. Methods in the modeling of events arising from quantum chromodynamics and electroweak boson production, which are major backgrounds in searches for new physics at the LHC, are also presented. No statistically significant excess of events is observed relative to the expectation from the standard model. Discussion of the non-excluded regions of the model parameter space is given. Lower limits on the masses of supersymmetric particles are determined at 95% confidence level in the context of simplified models with top quark production. For a model with direct top squark pair production followed by the decay of each top squark to a top quark and a neutralino, top squark masses up to 1020 GeV and neutralino masses up to 430 GeV are excluded. For a model with pair production of gluinos followed by the decay of each gluino to a top quark-antiquark pair and a neutralino, gluino masses up to 2040 GeV and neutralino masses up to 1150 GeV are excluded. These limits extend previous results obtained with 8 TeV data and 2.3 fb-1 13 TeV data.

Supersymmetry is an attractive extension of the standard model of particle physics. It associates to every bosonic degree of freedom a fermionic one and vice versa. Supersymmetry unifies the coupling constants of the electromagnetic, weak and strong forces at a high scale and provides a candidate for the elusive dark matter. Supersymmetry could be discovered at the LHC, the proton--proton collider at CERN which has started operations in 2008. The LHC is foreseen to have a center--of--mass energy of 14~TeV, opening up a new mass range to be explored to search for supersymmetric particles with the ATLAS and CMS experiments. The development and production of electronics for these detectors has been a challenge, e.g. for the readout board for the electromagnetic calorimeter. Reconstructing the physics events with the best precision, in particular the reconstruction and identification of electrons and photons in the large QCD background has been prepared in extensive test beam studies and Monte Carlo simulations. If the Higgs boson and supersymmetry are discovered, the properties of the (s)particles such as the masses, branching ratios must be measured precisely, either at the LHC or at a future e+e- linear collider. The SFitter project aims to determine the underlying theoretical model parameters from the correlated experimental measurements including theoretical errors. The methods are applied to the extraction of the fundamental parameters of supersymmetry as well the measurement of the Higgs boson couplings at the LHC. The extrapolation of the supersymmetric parameters from the weak scale to the Grand Unification Scale could provide the basis towards the inclusion of gravity.

No description available.

<p>Recent measurements show that dark matter makes up at least one fifth of the total energy density of the Universe. The nature of the dark matter is one of the biggest mysteries in current particle physics and cosmology.</p><p>Big Bang nucleosynthesis limits the amount of baryonic matter that can exist, and shows that the dark matter has to be non-baryonic. Particle physics provides some candidates for non-baryonic matter that could solve the dark-matter problem, weakly interacting massive</p><p>particles (WIMPs) being the most popular. If these particles were created in the early Universe a substatial relic abundance would exist today. WIMPs in our galactic halo could be gravitationally bound in the Solar System and accumulate inside heavy bodies like the Earth. Supersymmetric extensions to the Standard Model give a viable WIMP dark matter candidate in the form of the lightest neutralino. This thesis describes an indirect search for WIMPs by the neutrino signature from neutralino annihilation at the core of the Earth using the AMANDA detector. As opposed to previous dark matter searches with AMANDA, this work focuses on the hypothesis of a relatively light WIMP particle with mass of 50-250GeV/c²</p><p>The AMANDA neutrino telescope is an array of photomultiplier tubes installed in the clear glacier ice at the South Pole which is used as Cherenkov medium. Data taken with AMANDA during the period 2001-2003 is analyzed. The energy threshold of the detector is lowered by the use of a local correlation trigger, and the analysis is taylored to select vertically upgoing low energy events. No excess above the expected atmospheric neutrino background is found. New limits on the flux of muons from WIMP annihilations in the center of the Earth are calculated.</p>

This work is focused on the different supersymmetric extensions of the Landau model. We aim to fully solve each model and describe its energy levels, wavefunctions, Hilbert space and define a norm on it, as well as find symmetry generators and transformations with respect to them. Several possible generalizations were considered before. It was found for Landau model on the so called Superflag manifold as well as planar Superflag and Superplane Landau models that standard norm on the Hilbert space is not positive definite. Later for planar cases it was found that it is possible to fix this by introducing a new norm which will be invariant and positive definite. Surprisingly this procedure brings up "hidden" symmetries for the known super Landau models. In the dissertation we apply the same procedure for Landau model on superpshere and Superflag manifolds. It turns out that superpsherical Landau model is equivalent to the Superflag model with one of the parameters fixed. Because the model on superpshere can be recovered from the Superflag we will do calculations of corrected norm only for the Superflag. After this we develop a different generalization of the Superplane Landau model. Starting with Lagrangian in a superfield form we introduce two arbitrary functions of superfields K(Φ) and V(Φ) into the Lagrangian. We follow with the component form of Lagrangian. The quantization of the model is possible, and we will show that there is a reparametrization which turn equation of motion of the first scheme into the second set. Standard metric is again non-positive definite and we apply already known procedure to correct it. It will not be possible to solve Schrodinger equations in general with undefined K and V, so we consider one specific case which give us Landau model on a sphere with N = 2 supersymmetry, which put it apart from the superspherical Landau model, which have a superpshere for a target space but do not possess supersymmetry.

No description available.

Cette thèse intitulée « Studies of fractional D-branes in the gauge/gravity correspondence & Flavored Chern-Simons quivers for M2-branes » se place dans le cadre de la théorie des cordes, en physique théorique. Elle consiste en une introduction suivie de deux parties. Dans l'introduction sont résumés les différents outils de théorie des cordes qui seront utilisés. La première partie étudie des théories de type quiver en 3+1 dimensions et leur dual gravitationnel, qui découlent de la considération de D-branes fractionnaires vivant sur des espaces possédant des singularités en codimension complexe un. La thèse principale de cette partie est que la solution de supergravité de Bertolini et al. 2001 and Polchinski 2001 pour des branes de type N=2 a une interprétation dans la théorie des champs de type quiver duale comme un groupe de renormalisation de type cascade qui résulte d'un choix particulier sur la branche de Coulomb de la théorie. Cette compréhension nouvelle permet d'étudier des solutions de supergravité plus générales. Elle donne aussi une plus grande compréhension des branes N=2 dans des contextes avec seulement une supersymmétrie N=1. La second partie de la thèse étudie les quivers de type Chern-Simons, récemment apparus dans la littérature, décrivant des théories en dimension 2+1, qui sont conjecturé dual à des solutions de M-théorie. Il est montré que des théories plus générales que des quivers, possédant également des champs dans la représentation fondamentale des groupes de jauges, permettent la description de M2-branes sur des espaces possédant des singularités de dimension complexe deux, du moins du point de vue de la structure complexe, dans le cas où seules 4 supercharges sont préservées. La thèse principale est que la considération des operateurs monopoles diagonaux dans la théorie de champs N=2 supersymmétrique en 2+1 dimensions, plus une relation entre ces opérateurs proposée comme conjecture, permettent de reproduire l'espace des modules d'une M2-brane sur n'importe quelle géométrie torique ayant des singularités en codimension complexe deux.

No description available.