<p>The capability of encrypting top secret information remains as a major research problem in the GGH cryptosystem, which depends on various attacking methods. The early approaches to attacking the GGH cryptosystem mainly relied on special properties of the lattice generated by the vectors of the private key. Consequently, those attacks are not appropriate for general cases.</p> <p>This thesis presents a GGH attacking method for general cases. A lattice basis reduction algorithm is applied to the public key to get a better basis, which is used to decrypt the ciphertext. In the proposed approach, we concentrate on three lattice reduction algorithms: the LLL algorithm, the approximate optimally-reduced algorithm, and the optimally-reduced algorithm. We have implemented a package in MATLAB for the GGH cryptosystem and the three algorithms. We experimented with two groups of experiments and obtained promising results for lattices of low dimensions.</p> / Thesis / Master of Science (MSc)

Diese Arbeit präsentiert die Messung der Produktion eines einzelnen top quarks im s-channel. Dazu wird der 13 TeV ATLAS Datensatz, welcher von 2015 bis 2018 aufgenommen wurde und insgesamt 139 fb^−1 integrierte Luminositat hat, analysiert. Die große Schwierigkeit dieser Analyse ist die überwältigende Menge an Untergrund. Nach einer optimisierten Auswahl von Ereignissen stammen nur 3 % der Ereignisse von dem gesuchten Prozess. Demzufolge muss der Untergrund so gut wie möglich von dem Signal getrennt werden. In dieser Analyse wird die Matrixelement Methode verwendet. Diese Methode wendet das Neyman-Pearson Lemma, das die optimale Teststatistik beschreibt, auf dieses Teilchenphysik Experiment an. Die Likelihood Funktionen werden durch eine Faltung der Matrixelemente, die die harte Streuung beschreiben, mit den Transferfunktionen, die für die Modelierung der Detektoreffekte zuständig sind, berechnet. Wegen begrenzter Rechenkapazitäten kann dabei nur die erste Ordnung der Näherung in die Berechnung einbezogen werden. Diese Arbeit stellt außerdem Studien vor, die das Ziel haben diese Methode zu verbessern. Dazu wurden die Transferfunktion neu bestimmt. Außerdem wird ein Neuronales Netzwerk zur Identifizierung des Signals angewendet. Um das Resultat zu extrahieren wurde eine statistisches Modell der diskriminierenden Variable der Matrixelement Methode erstellt und mit Hilfe des profile likelihood Fits wurde der Parameter μ, der als Quotient aus dem gemessenen s-channel Wirkungsquerschnitt zu dem vom Standard Modell vorhergesagten Wirkungsquerschnitt definiert ist, bestimmt. Das Resultat der Analyse ist μ = 1.28 ^+0.36_− 0.31. Dies stimmt mit der Standard Modell Vorhersage überein. Die gemessene Signifikanz beträgt 4.19 σ. Dies ist die höchste jemals gemessene Signifikanz für die s-channel Produktion eines einzelnen top quarks in Proton-Proton Kollisionen. / This thesis presents the measurement of the single top s-channel production with the ATLAS detector. The analysis is based on data collected between 2015 and 2018, at a center-of-mass energy of 13 TeV and with an integrated luminosity of 139 fb^−1. The main challenge of this analysis is the overwhelming background. After an optimized selection of events the signal amounts to only approximately 3 % of all events in the signal region. This necessitates the best possible separation of signal and background. In this thesis, the Matrix Element is utilized. The underlying principle for this method is the Neyman-Pearson lemma which states the optimal test statistic. The likelihoods are computed by a convolution of the matrix elements describing the hard scattering process and the transfer functions which model the detector effects. Due to limited computing resources, only the leading order approximation can be calculated. This thesis further investigates methodologies aimed at enhancing the effectiveness of the signal separation process. For that reason, the transfer functions are updated and a study in which a neural network uses the event likelihoods of the Matrix Element Method as in- put to produce a different discriminating variable is shown. To extract the final result, a statistical analysis of the discriminating variable result- ing from the Matrix Element Method is preformed. A statistical model is built and the profile likelihood fit is used to extract the parameter of interest μ which is the ratio of the observed s-channel single top production cross-section to the Standard Model expectation. The result of the analysis is μ = 1.28 ^+0.36_− 0.31 which is in agreement with the Standard Model. The observed significance of this analysis is 4.19 σ. This is the highest measured significance of the s-channel single top production in proton-proton collisions.

Σκοπός της εργασίας είναι η παρουσίαση των εξισώσεων κίνησης του στερεού σώματος και η μελέτη δύο σημαντικών επιλύσιμων περιπτώσεων κίνησης στρόβου (Lagrange, Euler) . Στo πρώτο κεφάλαιο περιγράφουμε την κίνηση ενός στερεού σώματος χρησιμοποιώντας την ομάδα στροφών. Αποδεικνύουμε το θεώρημα Chasles το οποίο μας δείχνει πως η μετακίνηση ενός στερεού μπορεί να αποσυντεθεί σε περιστροφή γύρω από έναν άξονα και μεταφορά πάνω σε αυτόν. Στη συνέχεια σκοπός μας είναι η κατανόηση της γωνιακής ταχύτητας ενός στερεού σώματος. Σημαντικό ρόλο σε αυτή την πορεία παίζει τόσο το αδρανειακό όσο και το ενσωματωμένο στο στερεό σύστημα αναφοράς. Έπειτα δίνονται οι ορισμοί της ενέργειας, της στροφορμής, της ροπής και οι εκφράσεις τους συναρτήσει γνωστών πλέον εννοιών από τα προηγούμενα. Το κεφάλαιο ολοκληρώνεται με την Δυναμική που έχει ως αντικείμενο μελέτης και έρευνας τη κίνηση των σωμάτων υπό την επίδραση δυνάμεων, και καταλήγει στην παρουσίαση των εξισώσεων Euler. Στο δεύτερο κεφάλαιο στρέφουμε το ενδιαφέρον μας στις εφαρμογές και παρουσιάζουμε την επίλυση δύο σημαντικών προβλημάτων της μηχανικής: η κίνηση ενός συμμετρικού στρόβου που κινείται υπό την επίδραση του βάρους του έχοντας ένα σταθερό σημείο (ο στρόβος του Lagrange) και η κίνηση ενός στερεού που κινείται χωρίς την επίδραση εξωτερικών ροπών (ο στρόβος του Euler). Οι λύσεις εκφράζονται μέσω Ελλειπτικών Συναρτήσεων. Τέλος, στο τρίτο κεφάλαιο παρατίθενται σχόλια στις εργασίες των Holmes - Marsden και των Heijden - Yagasaki που αφορούν την ύπαρξη χαοτικής συμπεριφοράς στην διαταραγμένη περίπτωση Lagrange, που αναφέρεται σε σχεδόν συμμετρικό στρόβο. / Σκοπός της εργασίας είναι η παρουσίαση των εξισώσεων κίνησης του στερεού σώματος και η μελέτη δύο σημαντικών επιλύσιμων περιπτώσεων κίνησης στρόβου (Lagrange, Euler) . Στo πρώτο κεφάλαιο περιγράφουμε την κίνηση ενός στερεού σώματος χρησιμοποιώντας την ομάδα στροφών. Αποδεικνύουμε το θεώρημα Chasles το οποίο μας δείχνει πως η μετακίνηση ενός στερεού μπορεί να αποσυντεθεί σε περιστροφή γύρω από έναν άξονα και μεταφορά πάνω σε αυτόν. Στη συνέχεια σκοπός μας είναι η κατανόηση της γωνιακής ταχύτητας ενός στερεού σώματος. Σημαντικό ρόλο σε αυτή την πορεία παίζει τόσο το αδρανειακό όσο και το ενσωματωμένο στο στερεό σύστημα αναφοράς. Έπειτα δίνονται οι ορισμοί της ενέργειας, της στροφορμής, της ροπής και οι εκφράσεις τους συναρτήσει γνωστών πλέον εννοιών από τα προηγούμενα. Το κεφάλαιο ολοκληρώνεται με την Δυναμική που έχει ως αντικείμενο μελέτης και έρευνας τη κίνηση των σωμάτων υπό την επίδραση δυνάμεων, και καταλήγει στην παρουσίαση των εξισώσεων Euler. Στο δεύτερο κεφάλαιο στρέφουμε το ενδιαφέρον μας στις εφαρμογές και παρουσιάζουμε την επίλυση δύο σημαντικών προβλημάτων της μηχανικής: η κίνηση ενός συμμετρικού στρόβου που κινείται υπό την επίδραση του βάρους του έχοντας ένα σταθερό σημείο (ο στρόβος του Lagrange) και η κίνηση ενός στερεού που κινείται χωρίς την επίδραση εξωτερικών ροπών (ο στρόβος του Euler). Οι λύσεις εκφράζονται μέσω Ελλειπτικών Συναρτήσεων. Τέλος, στο τρίτο κεφάλαιο παρατίθενται σχόλια στις εργασίες των Holmes - Marsden και των Heijden - Yagasaki που αφορούν την ύπαρξη χαοτικής συμπεριφοράς στην διαταραγμένη περίπτωση Lagrange, που αναφέρεται σε σχεδόν συμμετρικό στρόβο.

Cette thèse présente une mesure de la section efficace de production du quark-top célibataire en voie t avec 1.04 fb-1 de données recueillies par le détecteur ATLAS au LHC à partir de collisions proton-proton d' énergie centre de masse sqrt(s) = 7 TeV. Les événements sélectionnés contiennent un lepton, de l'énergie transverse manquante, et deux ou trois jets, l'un d'eux étant étiqueté comme étant issu d'un quark-b. Le modèle pour le bruit de fond se compose des processus multijets, W+jets et production de paires de quarks top ainsi que de contributions moindres venant d' événements Z+jets et diboson. En utilisant une sélection basée sur la distribution d'un discriminant multivarié construit avec des arbres de décision stimulés, la section efficace de production de quark-top célibataire en voie t a été mesurée. La valeur de 97.3+30.7-30.2 pb a été obtenue. Ce résultat est en bon accord avec la prédiction du Modèle Standard. En supposant que les éléments de la matrice CKM reliée au quark-top obéissent à la relation |Vtb|>>|Vts|, jVtd|, la force du couplage W-t-b est extraite à partir de la section efficace mesurée, |Vtb| = 1.23+0.20-0:19. Si on suppose que |Vtb| <= 1, une limite inférieure |Vtb| > 0.61 est obtenue avec un niveau de confiance de 95%.

In the presented diploma thesis we study the reconstruction of the top antitop system in proton-proton colisions with central mass energy 7 TeV de- livered by LHC accelerator at CERN to the ATLAS experiment. ALPGEN and MC@NLO generators are described as two main method of top antitop pairs simulations. We compare events simulated by generators to data from LHC. The background and selection criteria are summarized. Next we de- scribed various methods of the top antitop reconstruction. Finally the Z particle was also studied. 1

Trata do desenvolvimento de uma metodologia para parametrização de equipamentos mecânicos pressurizados. Objetiva criar sistemas para geração de famílias de equipamentos petroquímicos e reduzir o tempo total de elaboração do projeto, desenhos e listas de materiais em até 80%, diminuir em até 70% o tempo consumido na geração de fichas de corte e mapas de solda na execução de roteiros de fabricação e ainda aprimorar a aquisição de materiais e componentes devido à padronização das entradas de projeto. Relata que os sistemas CAD (Computer-Aided Design) tridimensionais paramétricos têm papel cada vez mais destacado no desenvolvimento de equipamentos, porém alguns setores tradicionais da indústria brasileira apresentam ainda certa resistência ao emprego desta tecnologia. Demonstra que diante dos desafios impostos pela exploração de petróleo na camada do Pré-Sal e o grande volume de investimentos da PETROBRAS na expansão do setor produtivo ligado à extração e refino de petróleo, as empresas fornecedoras de equipamentos para o setor petroquímico são obrigadas a se modernizar e buscar novos paradigmas de projeto e fabricação para atender à demanda. Explica que o emprego produtivo de sistemas CAD 3D paramétricos se torna essencial neste cenário. Aplica a metodologia que foi desenvolvida baseada na abordagem top-down para modelagem de montagens, e afirma esta metodologia pode ser adaptada a qualquer sistema CAD 3D paramétrico comercial, com baixo consumo de recursos computacionais. Apresenta para validação um exemplo de aplicação passo a passo da metodologia para um equipamento. Mostra que a metodologia foi aplicada também para a construção de uma família de vasos de pressão verticais suportados por saia, com o intuito de avaliar o desempenho, com a obtenção de resultados significativos. Discute os problemas e dificuldades enfrentados na implantação do sistema paramétrico, juntamente com as alterações que este sistema trás na estrutura organizacional tradicional de empresas de bens de capital. Conclui que a metodologia desenvolvida apresentou resultados dentro dos objetivos estabelecidos e é uma alternativa viável para projetos mecânicos, que possibilita ganho de produtividade significativo. / This work addresses a methodology for the parameterization of pressurized mechanical equipments. It focuses on creating systems to generate an assembly of petrochemical equipments, hence reducing the total time of project designs, layouts and bill of material until 80%, decreasing until 70% the time consumed for executing manufacturing instructions and also improving materials and components acquisition due to the standardization of project entries. The study reports that three-dimensional parametric CAD systems (Computer-Aided Design) have an increasingly prominent role in the development of equipments, however some traditional sectors in the Brazilian industry are still somewhat resistant to using this technology. This work shows that with the challenges posed by oil exploration in the pre-salt layer and PETROBRAS large investments in the productive expansion sector for oil extraction and refining, the equipment supply companies servicing the petrochemical industry are forced to modernize and seek new design and manufacturing paradigms to meet the demands. It explains that the productive use of 3D parametric CAD systems are essential in this scenario. The methodology that was developed based on the top-down approach for assembly modeling is applied, thereby showing that this methodology can be adapted to any commercial 3D parametric CAD system, with low computational consumption of resources. For validation, it shows a step by step application example of the methodology in one equipment. It shows that the methodology was also applied to the construction of a family of skirt supported vertical pressure vessels, in order to evaluate the performance, with significant results. This work discusses the problems and difficulties faced in implementing the parametric system, along with the changes this system brings in the traditional organizational structure of capital goods companies. It concludes that this methodology presented results within the stated objectives and that it is a viable alternative for mechanical designs, hence enabling significant productivity gains.

Trata do desenvolvimento de uma metodologia para parametrização de equipamentos mecânicos pressurizados. Objetiva criar sistemas para geração de famílias de equipamentos petroquímicos e reduzir o tempo total de elaboração do projeto, desenhos e listas de materiais em até 80%, diminuir em até 70% o tempo consumido na geração de fichas de corte e mapas de solda na execução de roteiros de fabricação e ainda aprimorar a aquisição de materiais e componentes devido à padronização das entradas de projeto. Relata que os sistemas CAD (Computer-Aided Design) tridimensionais paramétricos têm papel cada vez mais destacado no desenvolvimento de equipamentos, porém alguns setores tradicionais da indústria brasileira apresentam ainda certa resistência ao emprego desta tecnologia. Demonstra que diante dos desafios impostos pela exploração de petróleo na camada do Pré-Sal e o grande volume de investimentos da PETROBRAS na expansão do setor produtivo ligado à extração e refino de petróleo, as empresas fornecedoras de equipamentos para o setor petroquímico são obrigadas a se modernizar e buscar novos paradigmas de projeto e fabricação para atender à demanda. Explica que o emprego produtivo de sistemas CAD 3D paramétricos se torna essencial neste cenário. Aplica a metodologia que foi desenvolvida baseada na abordagem top-down para modelagem de montagens, e afirma esta metodologia pode ser adaptada a qualquer sistema CAD 3D paramétrico comercial, com baixo consumo de recursos computacionais. Apresenta para validação um exemplo de aplicação passo a passo da metodologia para um equipamento. Mostra que a metodologia foi aplicada também para a construção de uma família de vasos de pressão verticais suportados por saia, com o intuito de avaliar o desempenho, com a obtenção de resultados significativos. Discute os problemas e dificuldades enfrentados na implantação do sistema paramétrico, juntamente com as alterações que este sistema trás na estrutura organizacional tradicional de empresas de bens de capital. Conclui que a metodologia desenvolvida apresentou resultados dentro dos objetivos estabelecidos e é uma alternativa viável para projetos mecânicos, que possibilita ganho de produtividade significativo. / This work addresses a methodology for the parameterization of pressurized mechanical equipments. It focuses on creating systems to generate an assembly of petrochemical equipments, hence reducing the total time of project designs, layouts and bill of material until 80%, decreasing until 70% the time consumed for executing manufacturing instructions and also improving materials and components acquisition due to the standardization of project entries. The study reports that three-dimensional parametric CAD systems (Computer-Aided Design) have an increasingly prominent role in the development of equipments, however some traditional sectors in the Brazilian industry are still somewhat resistant to using this technology. This work shows that with the challenges posed by oil exploration in the pre-salt layer and PETROBRAS large investments in the productive expansion sector for oil extraction and refining, the equipment supply companies servicing the petrochemical industry are forced to modernize and seek new design and manufacturing paradigms to meet the demands. It explains that the productive use of 3D parametric CAD systems are essential in this scenario. The methodology that was developed based on the top-down approach for assembly modeling is applied, thereby showing that this methodology can be adapted to any commercial 3D parametric CAD system, with low computational consumption of resources. For validation, it shows a step by step application example of the methodology in one equipment. It shows that the methodology was also applied to the construction of a family of skirt supported vertical pressure vessels, in order to evaluate the performance, with significant results. This work discusses the problems and difficulties faced in implementing the parametric system, along with the changes this system brings in the traditional organizational structure of capital goods companies. It concludes that this methodology presented results within the stated objectives and that it is a viable alternative for mechanical designs, hence enabling significant productivity gains.

Este trabalho consistiu em analisar a possibilidade de verificação da violação de sabor em correntes neutras intermediadas por glúons de Kaluza-Klein (GKK) através do modelo de dimensões extras compactas e curvas. Este introduz a possibilidade de violação de sabores em correntes neutras através de processos do tipo próton/próton em top/anti-quark c. Inicialmente estudamos o comportamento de jatos com altos momentos transversos (da ordem de 300 GeV) e suas subestruturas. Após isto, estudamos a detecção do quark top através dos algoritmos HEPTopTagger e Johns Hopkins (fizemos uma breve comparação entre eles). Por último, propusemos duas maneiras de encontrar os GKK. Uma delas, através da procura de somente quarks top. A outra, através da procura de um quark top e um jato sem subestrutura (algoritmo do tipo TJ). Pudemos ver que a possibilidade de encontrar o fenômeno de violação de sabores é acessível (a razão S/B da ordem de 0,1) para ambos os casos de massa analisados através do algoritmo do tipo TJ. / This study was to examine the possibility of verifying the violation of flavor in neutral currents mediated by Kaluza-Klein gluons (GKK), in which it was introduced by compact warped extra dimensions. The possibility of violation of flavors in neutral currents occurs through processes like proton/proton into quark top/ antiquark charm. Initially we studied the behavior of jets with high transverse momentum (the order of 300 GeV) and its substructures. After this, we studied the detection of the top quark via HEPTopTagger and Johns Hopkins algorithms (we did a brief comparison between them). Finally, we proposed two ways to find the GKK. One of them, by searching for only quark top. The other, by looking for a quark top and a jet without substructure (algorithm of TJ type). We could see that the possibility of encountering the phenomenon of violation of flavors is accessible (the ratio S/B is the order of 0.1) in both cases of mass analyzed by TJ type algorithm.

A continuous top-k query retrieves the k most preferred objects from a data stream according to a given preference function. These queries are important for a broad spectrum of applications from web-based advertising, network traffic monitoring, to financial analysis. Given the nature of such applications, a data stream may be subjected at any given time to multiple top-k queries with varying parameter settings requested simultaneously by different users. This workload of simultaneous top-k queries must be executed efficiently to assure real time responsiveness. However, existing methods in the literature focus on optimizing single top-k query processing, thus would handle each query independently. They are thus not suitable for handling large numbers of such simultaneous top-k queries due to their unsustainable resource demands. In this thesis, we present a comprehensive framework, called MTopS for Multiple Top-K Optimized Processing System. MTopS achieves resource sharing at the query level by analyzing parameter settings of all queries in the workload, including window-specific parameters and top-k parameters. We further optimize the shared processing by identifying the minimal object set from the data stream that is both necessary and sufficient for top-k monitoring of all queries in the workload. Within this framework, we design the MTopBand algorithm that maintains the up-to-date top-k result set in the size of O (k), where k is the required top-k result set, eliminating the need for any recomputation. To overcome the overhead caused by MTopBand to maintain replicas of the top-k result set across sliding windows, we optimize this algorithm further by integrating these views into one integrated structure, called MTopList. Our associated top-k maintenance algorithm, also called MTopList algorithm, is able to maintain this linear integrated structure, thus able to efficiently answer all queries in the workload. MTopList is shown to be memory optimal because it maintains only the distinct objects that are part of top-k results of at least one query. Our experimental study, using real data streams from domains of stock trades and moving object monitoring, demonstrates that both the efficiency and scalability in the query workload of our proposed technique is superior to the state-of-the-art solutions.

The Higgs boson and the top quark have been a focus in modern elementary particle physics research because of their special roles in the Standard Model (SM) of particle physics. The studies of both particles are crucial for revealing the unsolved puzzles of modern particle physics. The coupling between the Higgs boson and the top quark, the top-Yukawa coupling, is one of the fundamental parameters in the SM that can potentially direct the future development of the theory of elementary particle physics. This thesis presents two analyses on the Higgs boson and the top quark, using proton-proton (pp) collision data collected by the ATLAS detector during 2012 and 2015. A search for the SM Higgs boson produced in association with a top quark pair (tt̄H) was performed using 20.3 fb⁻¹ of pp collision data at a centre-of-mass energy of √s = 8 TeV. The search is designed to be primarily sensitive to the H → bb decay mode. Events with one of two electrons or muons are used in the search. No significant excess of events is observed above the background predicted by the SM. An observed (expected) upper limit on the signal strength of 3.4 (2.2) times the SM prediction is obtained at 95% confidence level. The tt̄H signal strength, represented by the ratio of the measured tt̄H cross-section to the SM prediction, is found to be μ = 1.5 ± 1.1 for a Higgs boson mass of m_H = 125 GeV. A measurement of the top quark pair (tt̄) production cross-section was performed using 3.2 fb⁻¹ of pp collision data at √s = 13 TeV. The measurement uses events with an opposite-charge-sign electron-muon pair and exactly one and two jets originating from b quarks. The inclusive tt̄ production cross-section is measured to be σ_tt̄ = 818 ± 8(stat) ± 27(syst) ± 19(lumi) ± 12(beam) pb, where the uncertainties arise from data statistics, analysis systematic effects, the integrated luminosity and the LHC beam energy. The total relative uncertainty is 4.4%. The result is consistent with the theoretical prediction at the next-to-next-to-leading order accuracy in the strong coupling constant αs of QCD, with the resummation of next-to-next-to-leading logarithmic (NNLL) soft gluon terms. A fiducial cross-section corresponding to the experimental acceptance of leptons is also measured.