[pt] O experimento LHCb (CERN) tem como um de seus objetivos principais o estudo do fenômeno de Violalção da Simetria Carga-Paridade (CP), que seria uma das condições necessárias para assimetria de matéeria-antimatéria observada no Universo. O LHCb foi especialmente desenhado para coletar eventos com produção de mésons B (que contém o quark b), cujos decaimentos são a melhor fonte para o estudo da Violação de CP. A observação de efeitos de Violação de CP no decaimento B+- -> pi +- pi- pi+ depende fundamentalmente dos canais ressonantes intermediários que são produzidos. Ainda que experimentos recentes não tenham observado Violação de CP neste canal, a alta estatística a ser atingida pelo LHCb pode vir a permitir a observação de assimetrias no chamado Dalitz Plot, que fornece informações diretas sobre a dinâmica do decaimento. Nesta dissertação, apresentamos um estudo do decaimento B+- -> pi+- pi- pi+ com dados simulados do experimento LHCb. O objetivo é estabelecer o número de eventos deste canal que podem ser observados com a luminosidade integrada de 2 fb(-1), o que corresponderia a um ano nominal de tomada de dados. Foram feitos estudos com amostras simuladas de sinal e de fundo, de forma a estabelecer um critério de seleção de eventos que oferecesse uma alta eficiência para eventos de sinal, com grande rejeição para eventos de fundo. De acordo a este critério, o rendimento esperado para 2 fb(-1) é de cerca de 87 mil eventos B+- -> pi+- pi- pi+ , com um relação fundo/sinal da ordem de 2. / [en] The LHCb experiment (CERN) has the main objective of studying the phenomenon of Charge-Parity (CP) Violation, which is one of the requisites for observed matter-antimatter asymmetry in the universe. The LHCb has been specially designed to collect events with production of B mesons (containing the b quark), since their decays are the best source for the study of CP violation. The observation of effects of CP violation in the decay B+- -> pi+- pi- pi+ depends on its resonant intermediate states. Although CP violation has been observed in this channel so far, the high statistics to achieve by the LHCb may allow the observation of asymmetries in the so–called Dalitz plot distribution, which provides direct information about the dynamics of decay. In this dissertation we present a study of the decay B+- -> pi+- pi- pi+ with simulated data of the experiment LHCb. The goal is to establish the number of events in this channel that can be reached with the integrated luminosity of 2 fb(-1), corresponding to one nominal year of data taking. Studies were performed using signal and background samples, in order to establish selection criteria to achieve a high efficiency for signal events with high background rejection. We obtain an expected yield for 2 fb(-1) of about 87 thousand events of B+- -> pi+- pi- pi+ , with a background to signal ratio of about 2.

We present a first measurement of time-dependent CP-violation in B0 → D∗∓ ρ± , where D∗∓ → D0 π. The analysis was performed using the final Belle dataset containing 772 × 106 B ¯B pairs collected at the KEKB e+ e− collider. Three D0 decay modes are analyzed, K∓ π± , K∓ π± π0 , and K∓ π± π∓ π± . Since the studied decay is a scalar → vector vector decay, three helicity configurations are present. Exploiting the helicity configura- tions via angular analysis, the time-dependent CP-violation parameters encoding 2ϕ1 +ϕ3 are obtained from the fit. 1

This thesis is devoted to studies of the proper decay-time resolution function and particle decay vertex reconstruction tools, their applicability and role in the studies of time-dependent CP violation at the Belle II experiment. A positive effect of beam spot constraints and new beam spot calibration on the vertex reconstruction precision is seen via MC/data comparison. The core part of the work focuses on studying universality of the time resolution function across nine different neutral and charged B-meson decay channels. The possibility to use a single form of this function for all studied channels is demon- strated and supported by the consistency between the lifetime values used for simulation and obtained as results of the decay time difference fit. 1

The use of renewable energy is promoted worldwide to be less dependent on fossil fuels and nuclear energy. Therefore research in the field is driven to increase efficiency of renewable energy systems. This study aimed to develop a wind turbine for low wind speeds in South Africa. Although there is a greater tendency to use solar panels because of the local weather conditions, there are some practical implications that have put the use of solar panels in certain areas to an end. The biggest problem is panel theft. Also, in some parts of the country the weather is more suitable to apply wind turbines. Thus, this study focused on the design of a new concept to improve wind turbines to be appropriate for the low wind speeds in South Africa. The concept involves the implementation of a concentrator and diffuser to a wind turbine, to increase the power coefficient. Although the wind turbine was not tested for starting speeds, the implementation of the shroud should contribute to improved starting of the wind turbine at lower wind speeds. The configuration were not manufactured, but simulated with the use of a program to obtain the power production of the wind turbine over a range of wind speeds. These values were compared to measured results of a open wind turbine developed for South Africa. The most important matter at hand when dealing with a shrouded wind turbine is to determine if the overall diameter or the blade diameter of the turbine should be the point of reference. As the wind turbine is situated in a shroud that has a larger diameter than the turbine blades, some researchers believe that the overall diameter should be used to calculate the efficiency. Theory was revised to determine the available energy in the shroud after initial calculations showed that the power coefficients should have been higher than the open wind turbine with the same total diameter. A new equation was derived to predict the available energy in a shroud. The benefits of shrouded wind turbines are fully discussed in the dissertation content. / MSc (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

The use of renewable energy is promoted worldwide to be less dependent on fossil fuels and nuclear energy. Therefore research in the field is driven to increase efficiency of renewable energy systems. This study aimed to develop a wind turbine for low wind speeds in South Africa. Although there is a greater tendency to use solar panels because of the local weather conditions, there are some practical implications that have put the use of solar panels in certain areas to an end. The biggest problem is panel theft. Also, in some parts of the country the weather is more suitable to apply wind turbines. Thus, this study focused on the design of a new concept to improve wind turbines to be appropriate for the low wind speeds in South Africa. The concept involves the implementation of a concentrator and diffuser to a wind turbine, to increase the power coefficient. Although the wind turbine was not tested for starting speeds, the implementation of the shroud should contribute to improved starting of the wind turbine at lower wind speeds. The configuration were not manufactured, but simulated with the use of a program to obtain the power production of the wind turbine over a range of wind speeds. These values were compared to measured results of a open wind turbine developed for South Africa. The most important matter at hand when dealing with a shrouded wind turbine is to determine if the overall diameter or the blade diameter of the turbine should be the point of reference. As the wind turbine is situated in a shroud that has a larger diameter than the turbine blades, some researchers believe that the overall diameter should be used to calculate the efficiency. Theory was revised to determine the available energy in the shroud after initial calculations showed that the power coefficients should have been higher than the open wind turbine with the same total diameter. A new equation was derived to predict the available energy in a shroud. The benefits of shrouded wind turbines are fully discussed in the dissertation content. / MSc (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

The study of flavour physics allows for the Standard Model (SM) to be tested to higher energies than can be accessed through direct searches. The SM is known not to provide enough of a difference between matter and anti-matter, termed CP violation, to explain the dominance of matter in our universe. One of the main purposes of the LHCb experiment is to search for new sources of CP violation in the decays of B mesons. Flavour changing neutral current (FCNC) interactions are forbidden at tree level in the SM, and can therefore only be accessed through quantum loops. In New Physics scenarios such as Supersymmetry, new particles could appear in those loops introducing new sources of CP violation. The Bos→ØØ decay proceeds via the b → sss FCNC transition. Triple products provide a method of exploiting the angular distributions of P → V V decays to create T-odd observables. Asymmetries of these T-odd observables, averaged over the initial flavour of the Bos meson provide a measure of T violation. Assuming CPT conservation, violation of time reversal infers CP violation. The CP-violating weak phase in the interference between Bos mixing and the decay to two Ø mesons is predicted to be close to zero in the SM. The measurements of the triple product asymmetries and the CP-violating weak phase have been performed using 1.0 fb-1 of LHCb data. Events where kaon pairs originate from a spin-0 or non-resonant state are accounted for with the associated angular distributions. Triple product asymmetries are measured to be AU = -0:055 ± 0:036(stat) ± 0:018(syst) and Av = 0:010 ± 0:036(stat) ± 0:018(syst). The CP-violating phase is found to be in the interval [-2:46,-0:76] rad at 68% confidence level. The p-value for the hypothesis of zero radians is found to be 16 %. These results represent the most accurate measurements of the triple product asymmetries and the first measurement of the CP-violating weak phase.

The LHCb experiment is an experiment based at the LHC in Geneva and is dedicated to the study of mesons containing bottom and charm quarks. One of the primary goals of the physics at LHCb is to measure CP-violating effects which lead to a dominance of matter over anti-matter in the universe. This thesis presents the measurement of the CP-violating phase Ø s which is one of the golden channels at LHCb. This phase is observed as the interference between mixing of B0s ↔ B-0s and decay of B0s → J/ψ K+K−. The results, based upon the 1.0 fb−1 dataset collected by LHCb during 2011, are: Ø s = 0.07±0.09±0.01 rad , ∆Γs = 0.100±0.016±0.002 ps−1 , Γs = 0.663±0.005±0.006 ps−1 . This analysis is also able to measure the mixing parameter ms = 17.71±0.10±0.01 ps−1. To improve upon this measurement the B0s → J/ψ K+K− analysis is combined with the B0s → J/ψ π+ π − decay channel to make the most accurate measurements to date of, Ø s = 0.01±0.07±0.01 rad, ∆Γs = 0.106±0.011±0.007 ps−1 and Γs = 0.661±0.004±0.006 ps−1. As an integral part of this work a comprehensive software suite known as RapidFit was developed, which is used by many other physicists and this is described.

Pourquoi reste-t-il de la matière dans l’univers ? Depuis la découverte de l’anti-matière, miroir de la matière dont nous sommes constitués et s’annihilant de prime abord parfaitement avec cette dernière, ce mystère stimule l’étude des propriétés communes et distinctes entre particules et anti-particules. Dans ce cadre, il a été établi au vu des interactions dites de jauge (en particulier les interactions électrofaibles) que la symétrie intrinsèque entre particules et anti-particules est la combinaison subtile du conjugué de charge (C) et de la parité d’espace (P) : la symétrie CP. Ainsi, un comportement distinct entre matière et anti-matière est caractérisé au niveau fondamental par une violation de CP. D’une part, une telle violation a été mise en évidence expérimentalement dans la désintégration de mesons K et B, où la production de particules dans certains canaux est favorisée. D’autre part, la violation de CP est l’une des conditions requises à la création d’un excès de matière durant l’évolution de l’univers. Dans la présente thèse, nous étudions deux aspects de cette asymétrie entre matière et anti-matière. Tout d’abord, un scénario de création d’un excès de matière dans l’évolution de l’univers basé sur la désintégration de neutrinos lourds est étudié. Les récents résultats expérimentaux sur l’existence d’une masse pour les neutrinos rendent très attractif ce scénario. Bien que le schéma général repose uniquement sur les interactions liées à la masse des particules (secteur scalaire), nous le prolongeons ici dans la perspective plus naturelle de l’unification des interactions de jauge, seule motivation complète à l’inclusion de neutrinos lourds dans le spectre des particules. L’inclusion d’interactions de jauge liées aux neutrinos lourds complète ainsi la description. Les résultats tirés sur les paramètres de masse des neutrinos, grandes inconnues de la physique des particules, s’en voient modifiés de manière importante. Ensuite, la question de l’origine de la violation de CP est posée. En effet, dans la description standard des interactions faibles, la violation de CP est explicite et résulte uniquement de la liberté pour les couplages de masse (couplages de Yukawa) d’être des nombres complexes. Ainsi, aucune compréhension fondamentale sur la différence de comportement entre particules et anti-particules n’est apportée. Nous proposons dans ce sens une source de violation de CP par la compactification d’une théorie de jauge dans un espace de dimensions étendues. A partir de couplages réels, une valeur classique de la composante supplémentaire des bosons de jauge fournit une masse effective complexe aux fermions. Les conditions de l’obtention d’une violation de CP physique sont alors étudiées. Nous identifions la structure minimale pour rendre compte des interactions électrofaibles tout en incluant une source de violation de CP dans ce contexte. L’unification avec les interactions fortes est alors établie dans une structure qui apporte une lumière différente sur les schémas d’unification usuels.

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