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Orientador: Sérgio Ferraz Novaes / Doutor

Orientador: Oscar José Pinto Éboli / Mestre

We apply the Jansson-Farrar JF12 magnetic field model in the context of point source searches by correlating the Telescope Array ultrahigh energy cosmic ray data and the IceCube-40 neutrino candidates, as well as other magnetic field hypotheses. Our field hypotheses are: no magnetic field, the JF12 field considering only the regular component, the JF12 full magnetic field, which is a combination of regular and random field components, and the standard turbulent magnetic field used in previous correlation analyses. As expected from a neutrino sample such as IceCube-40, consistent with atmospheric neutrinos, we have found no significant correlation signal in all the cases. Therefore, this paper is mainly devoted to the comparison of the effect of the different magnetic field hypotheses on the minimum neutrino source flux strength required for a 5σ discovery and the derived 90% C.L. upper limits. We also incorporate in our comparison the cases of different power law indices α= 2.2, α=2.5 for the neutrino point source flux. The differences in the 5σ discovery flux for our magnetic field hypotheses is ∼1%–50%, being the maximum difference with the regular JF12 field and standard turbulent field models, being the standard turbulent higher than the regular one, while the minimum is between the no magnetic field and regular JF12 field. Considering the current flux upper limits, we find that IceCube requires a lifetime ≳5 years to observe neutrino-UHECR correlation signals. Our analysis for different power law indices yielded the same relative behavior between different magnetic field models. / Tesis

The discovery of the Higgs boson in the 8 TeV run of the LHC [1, 2] marks one of the most important milestones in particle physics. Its mass is already known rather precisely: mh = 125.09 ± 0.21 (stat.) ±0.11 (syst.) GeV [3], and the signal strength of various LHC searches has been found consistent with the SM predictions. While this completes the Standard Model (SM) particle-wise, several questions still remain open, for example: (i) Is it possible to include the SM in a grand unified theory where all gauge forces unify? (ii) Is there a particle physics explanation of the observed dark matter relic density? (iii) What causes the hierarchy in the fermion mass spectrum and why are neutrinos so much lighter than the other fermions? What causes the observed mixing patterns in the fermion sector? (iv) What stabilizes the Higgs mass at the electroweak scale? Supersymmetric model address several of these questions and consequently the search for supersymmetry (SUSY) is among the main priorities of the LHC collaborations. Up to now no significant sign for physics beyond SM has been found. The combination of the Higgs discovery with the (yet) unsuccessful searches has led to the introduction of a model class called ‘natural SUSY’ [4–15]. Here, the basic idea is to give electroweak-scale masses only to those SUSY particles giving a sizeable contribution to the mass of the Higgs boson, such that a too large tuning of parameters is avoided. All other particle masses are taken at the multi-TeV scale. In particular, masses of the order of a few hundred GeV up to about one TeV are assigned to the higgsinos (the partners of the Higgs bosons), the lightest stop (the partner of the top-quark) and, if the latter is mainly a left-stop, also to the light sbottom In addition the gluino and the heavier stop masses should also be close to at most a few TeV. Neutrino oscillation experiments confirm that at least two neutrinos have a non-zero mass. The exact mass generation mechanism for these particles is unknown, and both the SM and the MSSM remain agnostic on this topic. Although many ways to generate neutrino mass exist, perhaps the most popular one is the seesaw mechanism [16–21]. The main problem with the usual seesaw mechanisms lies on the difficulty in testing its validity. In general, if Yukawa couplings are sizeable, the seesaw relations require Majorana neutrino masses to be very large, such that the new heavy states cannot be produced at colliders. In contrast, if one requires the masses to be light, then the Yukawas need to be small, making production cross-sections and decay rates to vanish. A possible way out of this dilemma lies on what 3 is called the inverse seesaw [22], which is based on having specific structures on the mass matrix (generally motivated by symmetry arguments) to generate small neutrino masses. This, at the same time, allows Yukawa couplings to be large, and sterile masses to be light. We consider here a supersymmetric model where neutrino data are explained via a minimal inverse seesaw scenario where the gauge-singlet neutrinos have masses in the range O(keV) to O(100 GeV). We explore this with a parametrization built for the standard seesaw, and go to the limit where the inverse seesaw emerges, such that Yukawas and mixings become sizeable. Although non-SUSY versions of this scenario can solve the dark matter and matter-antimatter asymmetry problems [23–25], we shall make no claim on these issues in our model. In view of the naturalness arguments, we further assume that the higgsinos have masses of O(100 GeV), whereas the gaugino masses lie at the multi-TeV scale (see [26] for an example of such a scenario). In addition, we assume all squarks are heavy enough such that LHC bounds are avoided, and play no role in the phenomenology within this work1. In contrast we allow for fairly light sleptons and investigate the extent to which current LHC data can constrain such scenarios. This paper is organized as follows: in the next section we present the model. Section III summarizes the numerical tools used and gives an overview of the LHC analysis used for these investigations. In Section IV we present our findings for the two generic scenarios which differ in the nature of the lighest supersymmetric particle (LSP): a Higgsino LSP and a sneutrino LSP. In Section V we draw our conclusions. Appendices A and B give the complete formulae for the neutrino and sneutrino masses. / Tesis

Orientador: Bruto Max Pimentel Escobar / Mestre

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Made available in DSpace on 2014-06-11T19:32:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-10-03Bitstream added on 2014-06-13T19:42:33Z : No. of bitstreams: 1 santos_as_dr_ift.pdf: 2147503 bytes, checksum: 5d62e5e2b0ada118a28a666128ee6e93 (MD5) / Modelosque preveem a existência de dimensões espaciais extras são estudados desde as primeiras décadas do século XX. São modelos que podem incorporar a gravitação à estrutura que descreve as demais interações e podem apresentar uma série de características interessantes como, por exemplo, candidatos à matéria escura. Nesse trabalho exploramos as consequências do modelo de Dimensões Extras Universais (UED) buscando pela produção de partículas de Kaluza-Klein cuja cadeia de decaimento leva à assinaturaµ±µ±+jatos+ET/ . O conjunto de dados analisados corresponde a uma luminosidade total integrada de 7,3 fb−1 coletada pelo detector DØ a partir de colisões próton-antipróton com energia de centro-de-massa de 1,96 TeV geradas pelo anel de colisão Tevatron do Fermilab. Uma vez que nenhum excesso foi observado nos dados, pode-se obter um limite inferior de 260 GeV para a escala de compactificaçãoR−1 do modelo. Este é o primeiro estudo a obter um limite direto para o modelo mínimo de UED / Models that predict the existence of extra spatial dimensions have been studied since the beginning of the 20th century. These models can incorporate gravity in the framework that describes the other interactions and they can present a number of interesting features such as a dark matter candidate. In this work, we explore the consequences of the Universal Extra Dimensions (UED) model by searching for the production of Kaluza-Klein particles whose decay chain leads to signatureµ±µ±+jets+ET/ . We employ the data set corresponding to an integrated luminosity of 7.3 fb−1, collected by the DØ detector at ap¯p collider at a center of mass energy of 1.96 TeV. Since no excess was observed in the data, we were able to set a lower limit on the compactification scale ofR−1> 260 GeV in the model. This is the first study to impose a direct limit on the minimal UED model

Orientador: Sérgio Ferraz Novaes / Coorientador: Pedro Galli Mercadante / Banca: Arthur Marques Moraes / Banca: Arthur Kós Antunes Maciel / Banca: Ricardo D'Elia Matheus / Banca: Leandro Salazar de Paula / Resumo: Modelosque preveem a existência de dimensões espaciais extras são estudados desde as primeiras décadas do século XX. São modelos que podem incorporar a gravitação à estrutura que descreve as demais interações e podem apresentar uma série de características interessantes como, por exemplo, candidatos à matéria escura. Nesse trabalho exploramos as consequências do modelo de Dimensões Extras Universais (UED) buscando pela produção de partículas de Kaluza-Klein cuja cadeia de decaimento leva à assinaturaµ±µ±+jatos+ET/ . O conjunto de dados analisados corresponde a uma luminosidade total integrada de 7,3 fb−1 coletada pelo detector DØ a partir de colisões próton-antipróton com energia de centro-de-massa de 1,96 TeV geradas pelo anel de colisão Tevatron do Fermilab. Uma vez que nenhum excesso foi observado nos dados, pode-se obter um limite inferior de 260 GeV para a escala de compactificaçãoR−1 do modelo. Este é o primeiro estudo a obter um limite direto para o modelo mínimo de UED / Abstract: Models that predict the existence of extra spatial dimensions have been studied since the beginning of the 20th century. These models can incorporate gravity in the framework that describes the other interactions and they can present a number of interesting features such as a dark matter candidate. In this work, we explore the consequences of the Universal Extra Dimensions (UED) model by searching for the production of Kaluza-Klein particles whose decay chain leads to signatureµ±µ±+jets+ET/ . We employ the data set corresponding to an integrated luminosity of 7.3 fb−1, collected by the DØ detector at ap¯p collider at a center of mass energy of 1.96 TeV. Since no excess was observed in the data, we were able to set a lower limit on the compactification scale ofR−1> 260 GeV in the model. This is the first study to impose a direct limit on the minimal UED model / Doutor

Tese (doutorado)—Universidade de Brasília, Instituto de Física, 2011. / Submitted by Sabrina Silva de Macedo (sabrinamacedo@bce.unb.br) on 2012-07-18T13:48:01Z No. of bitstreams: 1 2011_GuilhermeRochdeRezende.pdf: 1556298 bytes, checksum: 17150ea66fd838b29bfbd087ebbc6912 (MD5) / Approved for entry into archive by Patrícia Nunes da Silva(patricia@bce.unb.br) on 2012-08-09T02:57:46Z (GMT) No. of bitstreams: 1 2011_GuilhermeRochdeRezende.pdf: 1556298 bytes, checksum: 17150ea66fd838b29bfbd087ebbc6912 (MD5) / Made available in DSpace on 2012-08-09T02:57:46Z (GMT). No. of bitstreams: 1 2011_GuilhermeRochdeRezende.pdf: 1556298 bytes, checksum: 17150ea66fd838b29bfbd087ebbc6912 (MD5) / Neste trabalho utilizamos o formalismo da equação de Langevin generalizada, desenvolvido inicialmente por Robert Zwanzig e Hazime Mori, para estudarmos o comportamento de um tipo de motor browniano o motor liga-desliga aplicado no estudo de um separador de partículas e em um tipo de motor molecular: a cinesina. Neste estudo escolhemos quatro funções memórias diferentes e analisamos a influência destas memórias na velocidade e eficiência do motor browniano. _________________________________________________________________________________________ ABSTRACT / In this work we used the generalized Langevin equation formalism, initially developed by Robert Zwanzig and Hazime Mori, to study the behavior of a one type of Brownian motor the on-of ratchet applied in the study of a particle separator and a type of molecular motor: the kinesin. In this study we choose four different memory functions and analyze the influence of these memories at the speed and efficiency of the brownian motor.