Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Dr. Laura Reina, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Sept. 14, 2005). Document formatted into pages; contains xv, 212 pages. Includes bibliographical references.

Proefschrift Universiteit van Amsterdam. / Met een samenvatting in het Nederlands.

Proefschrift Universiteit van Amsterdam. / Naam van de auteur op de omslag: Thijs Cornelissen. Met samenvatting in het Nederlands.

A search for new neutral scalar bosons produced in association with a bottom-quark is performed. The analysis uses data acquired with proton-proton collisions at a center-of-mass energy of 8 TeV and observed with the ATLAS detector at the LHC, corresponding to 20.3 $fb^{-1}$ of integrated luminosity. The search focuses on scalar boson decays into tau lepton pairs, where each decays leptonically ($\tau \rightarrow l \nu_{\tau} \bar{\nu_{l}}$) resulting in one muon, one electron and four neutrinos. No significant excess is observed and upper limits on the signal strength are determined as a function of scalar boson mass.

Made available in DSpace on 2014-06-11T19:32:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-19Bitstream added on 2014-06-13T20:23:06Z : No. of bitstreams: 1 machado_acb_dr_ift.pdf: 714100 bytes, checksum: 7b80564011cbcd6e5a4857316583f95b (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Neste trabalho, propomos duas extensões multi-Higgs do modelo padrão com simetrias discretas abelianas e não abelianas e com o setor escalar que possui pelo menos um dubleto de Higgs para cada férmion do MP. Mostramos que do ponto de vista fenomenológico os modelos concordão com os dados experimentais e as massas e as matrizes de mistura CKM e PMNS são corretamente obtidas, para o primeiro modelo que descreve o setor dos quarks e dos léptons e para o segundo modelo, que descreve somente o setor dos léptons a matriz de mistura PMNS e as massas são devidamente obtidas / In this work we propose two multi-Higgs extension of the Standard Model with Abelian and non Abelian discrete symmetries and a scalar sector which has at least one Higgs doublet for each fermion of the Standard Model. From the phenomenological point of view the models are safe and the masses and the mixing matrices CKM and PMNS are properly obtained for the first model that describes the sector of quarks and leptons. The second model describes only the leptonic sector, but the mixing matrix and masses are also obtained in compliance with the experimental data

Orientador: Oscar José Pinto Éboli / Banca: Sérgio Ferraz Novaes / Banca: Rogério Rosenfeld / Banca: Alberto Franco de Sá Santoro / Banca: Orlando Luis Goulart Peres / Resumo: A procura por nova física em escala subatômica em anéis de colisão hadrônicos em dois cenários de grande interesse fenomenológico - o setor de quebra espontânea de simetria e a extensão com quebra de paridade R do MSSM - é apresentada nesta tese. Na primeira parte da tese, mostramos que extensões do Modelo Padrão ou do MSSM que incorporem um setor de quebra espontânea de simetria complexo, contendo um número arbitrário de dubletos e singletos de escalares de 'SU(2) IND. L' podem ser facilmente estudados no Large Hadron Collider (LHC) do CERN através do processo de fusão de bósons fracos com o subsequente decaimento em léptons. Cerca de 10 'fb POT. -1' a 50 'fb POT. -1' de luminosidade integrada serão necessários para se obter um sinal de 5'sigma' de significância estatística. Mostramos também que a distribuição de massa transversa dos bósons fracos pode ser usada para se distinguir o caso de um modelo contínuo de bósons de Higgs em relação ao caso do Modelo Padrão, contudo, o processo de fusão de glúons com o mesmo canal de decaimento dos bósons de Higgs pode ser mais promissor neste sentido. Na segunda parte da tese, calculamos as correções completas de Next-to-Leading-Order de SUSY-QCD à produção associada de stops/sbottoms e léptons no Tevatron e no LHC no âmbito do MSSM estendido por interações com quebra de paridade R. As correções de NLO aumentam as seções de choque totais em até 70%(50%) no Tevatron (LHC), ao mesmo tempo que reduzem a incerteza teórica relacionada à escolha das escalas de renormalização e fatorização. Desacoplando o espectro pesado de SUSY, mostramos que o alcance de procura do Tevatron e do LHC por leptoquarks escalares, que se acoplam a quarks up e down e que decaiam exclusivamente em quarks e léptons, pode ser aumentado usando-se as seções de choque de NLO. No caso do Tevatron, leptoquarks de massas até 310 GeV podem... / Abstract: We present the search for new physics at subatomic scales at hadron colliders in two important phenomenological scenarios -- the spontaneous symmetry breaking sector and the R-parity violating extension of the MSSM. In the first part of this thesis, we show that extensions of the Standard Model and the MSSM, which embody a complex spontaneous symmetry breaking sector containing an arbitrary number of 'SU(2) IND. L' escalar doublets and singlets, can be easily studied at the LHC in the weak boson fusion process with the subsequent decay to leptons. About 10 'fb POT. -1' a 50 'fb POT. -1' of integrated luminosity will be necessary in order to get a 5'sigma' level signal. We also show that the weak bosons' transverse mass distributions can be used to distinguish the continuum model from the Standard Model case, however, the gluon fusion process in the same decay channel may be more promising in this regard. In the second part of the thesis, we compute the full NLO SUSY-QCD corrections to the stop/sbottom lepton associated production at the Tevatron and at the LHC in the MSSM framework extended by R-parity breaking couplings. The NLO correc- tions increase the total cross sections up to 70%(50%) at the Tevatron(LHC) and reduce the theoretical uncertanties related to the choice of the renormalization and factorization scales. Decoupling the heavy SUSY spectrum, we show that the search reach of the Tevatron and the LHC for scalar leptoquarks, which couple to up and down quarks and decay exclusively to quarks and leptons, increases using the NLO rates. For the Tevatron, leptoquarks of masses up to 310 GeV can be excluded to 95% C.L., while for the LHC, leptoquarks of masses up to 3.1 TeV can be excluded at the same statistical level / Doutor

A search for a light charged Higgs boson (H^±) decaying into two jets (c¯s) using pp collisions at s = sqrt(7 TeV) is presented. A data sample corresponding to an integrated luminosity of 4.7 fb^−1 recorded by the ATLAS detector in 2011 has been analysed. The search is performed in the semi-leptonic t¯t channel, where one of the top quarks decays via t --> bH^±. The other top quark decays to bW, where the W boson decays to a lepton (e/μ) and a neutrino. The search is based on the invariant mass distribution of the two light jets in the final state as the discriminating variable. With no observation of an H^± signal, 95% confidence level(CL) upper limits are set on the decay branching ratio of top quarks to charged Higgs bosons. These limits are between 5% and 1% for charged Higgs boson masses between 90 and 150 GeV, and can be considered as model-independent limits on the decay branching ratio of top quarks to any charged boson beyond the Standard Model.

This thesis is dedicated to construct a non-abelian holographic dynamical minimal composite Higgs model. We first build a non-abelian bottom-up AdS/YM model that can explain the QCD meson spectrum well. The model is made non-abelian by considering non-abelian DBI action in the top-down model. We then change the dual theory from the QCD to the minimal composite Higgs model U (4)/Sp(4). By adding a second explicit U (4) → Sp(4) breaking through the NJL interaction at the boundary, we managed to construct a composite Higgs phase and a technicolor phase in this model. The transition between the two phases is also realized, which is controlled by the NJL coupling. This thesis is based on the works [1, 2]. / Diese Arbeit konstruiert ein nicht-abelsches holographisches dynamisches minimales Composite-Higgs-Modell. Wir erstellen zunächst ein nicht-abelsches Bottom-up-AdS/YM-Modell, das das QCD-Mesonenspektrum gut erklären kann. Das Modell ist nicht-abelsch, da die nicht-abelsche DBI-Wirkung im Top-Down-Modell berücksichtigt wird. Anschließend ändern wir die duale Theorie von der QCD auf das minimale Composite-Higgs-Modell U (4)/Sp(4). Durch das Hinzufügen einer zweiten expliziten Brechung U (4) → Sp(4), das die NJL-Wechselwirkung an der Grenze durchbricht, konstruierten wir in diesem Modell eine Composite-Higgs-Phase und eine Technicolor-Phase. Auch der Übergang zwischen den beiden Phasen wird realisiert, welcher durch die NJL-Kopplung gesteuert wird. Diese Arbeit basiert auf den Arbeiten [1, 2].