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The top quark has been extensively studied since the Large Hadron Collider (LHC) began operating in 2010. The excellent performance of both the LHC and the Compact Muon Solenoid (CMS) detector has enabled complex analyses of many properties of the top quark. In this thesis inclusive and differential top pair (tt) production cross sections have been measured. Inclusive tt cross sections of 145.6 ± 8.2 (stat.) +38.1/28.3 (syst.) pb and 237.4 ± 1.9 (stat.) +20.4/-16.9 (syst.) pb were measured at 7 TeV and 8 TeV center-of-mass collision energies using luminosities of 1 fb⁻¹ and 19.7 fb⁻¹, respectively. These measurements were performed in the semi-leptonic channel by means of a maximum likelihood t of the lepton's pseudorapidity. The work in this thesis focuses specifically on the muon-plus-jets channel. The methods used for measuring the inclusive cross sections were built upon to measure differential cross sections with respect to event level observables. These observables include the missing transverse energy (Emiss T ) as well as some other kinematic distributions involving the jets, lepton and Emiss T in the decay. These results are unfolded to remove detector and selection effects and have uncertainties in the range of 3% to 15%. A low uncertainty is achieved by normalising the differential cross section using the total cross section. This leads to cancellations of some uncertainties. The results were compared with different Monte Carlo generators and with different input parameters. No significant deviations from predictions of the Standard Model were observed. This thesis also contains test beam results on CMS ECAL Endcap Lead Tungstate (PbWO4) crystals. These crystals had been damaged using various doses of proton irradiation. The damage for some crystals is expected to be roughly equivalent to 300 fb-1 of integrated luminosity at √s = 14 TeV. The energy resolution for these crystals was seen to reduce by close to a factor of 20.

Over the last few decades, the Standard Model (SM) of particle physics has been used as a means of understanding the world around us. However, there is an increasing amount of data that suggests the SM of particle physics only describes nature up to energies of the electroweak scale. Extensions to the SM have been developed as a means of explaining experimental observation. If these extensions are indeed the correct mathematical descriptions of nature, the Large Hadron Collider (LHC), located at the European Center for Nuclear Research (CERN) near Geneva, Switzerland, is expected to produce new and exciting physics signatures that can shed light on the evolution of our universe since the early hypothesized Big Bang. Of particular interest are models that may lead to events with highly energetic tau lepton pairs. In this dissertation, focus is placed on a possible search for new heavy gauge bosons decaying to highly energetic tau pairs using a data sample corresponding to an integrated luminosity of 36 pb^-1 of proton-proton collisions at sqrt(s) = 7 TeV collected with the CMS detector at the CERN LHC. The number of observed events in the data is in good agreement with the predictions for SM background processes. In the context of the Sequential SM, a Z0 with mass less than 468 GeV/c^2 is excluded at 95 percent credibility level, exceeding the sensitivity by the Tevatron experiments at the Fermi National Accelerator Laboratory.

The Standard Model has granted exquisite power to predict the behaviour of high-energy particle collisions. It is not, however, without conceptual and empirical weaknesses. Several theories have been proposed which aim to resolve these difficulties. This thesis describes searches for two such theories: models of extra spatial dimensions, and supersymmetry. The Large Hadron Collider has extended the frontiers of energy and intensity in particle physics. In 2015, the LHC resumed proton–proton collisions at a centre-of-mass energy of 13 TeV. This increase over previous operation grants an enhancement in sensitivity to many processes beyond those of the Standard Model. Extra-dimensional theories address the hierarchical nature of the Standard Model. The lowered fundamental scale of gravity in these models allows a rich phenomenology at energies which may be accessible to the LHC. Some models predict the formation of microscopic black holes, which are the target of an analysis of collisions recorded by the ATLAS detector in 2015. No significant deviations from Standard Model predictions were observed. The constraints inferred on the parameters of the model are a significant advance on previous results. Lepton flavour is conserved in the Standard Model. This is not the result of a known fundamental symmetry, however. The latter part of this thesis proposes a search examining asymmetries of charge and flavour in the eμ final state. Models of supersymmetry with an R-parity-violating λ'₂₃₁ coupling are taken as motivation. The strategy is developed using collision data recorded by ATLAS in 2015 and 2016, and the most significant biasing effects are addressed.

OLIVEIRA JÚNIOR, R. I . Modelos de Randall Sundrum e estabilização do raio da dimensão extra. 2017. 54 f. Dissertaço (mestrado) - Universidade Federal do Ceará, Centro de Ciencias, Programa de Pós-Graduação em Fısica, Fortaleza, 2017. / Submitted by Pós-Graduação em Física (posgrad@fisica.ufc.br) on 2017-10-26T19:33:09Z No. of bitstreams: 1 2017_dis_rioliveirajunior.pdf: 803388 bytes, checksum: e30dc735640f5c347b38926012dc5612 (MD5) / Approved for entry into archive by Giordana Silva (giordana.nascimento@gmail.com) on 2017-10-30T14:55:42Z (GMT) No. of bitstreams: 1 2017_dis_rioliveirajunior.pdf: 803388 bytes, checksum: e30dc735640f5c347b38926012dc5612 (MD5) / Made available in DSpace on 2017-10-30T14:55:42Z (GMT). No. of bitstreams: 1 2017_dis_rioliveirajunior.pdf: 803388 bytes, checksum: e30dc735640f5c347b38926012dc5612 (MD5) Previous issue date: 2017 / In this dissertation we study The Randall Sundrum models type I and II and the stabilization of the radius of the extra dimension. Both the types were elaborated by Lisa Randall and Ramman Sundrum. The type I was developed to solve the gauge hierarchy problem (big discrepancy between the energy scale of the standard model(103GeV ) and the energy scale of the gravity (1019GeV ) . The type II explain, in details, the behavior of the gravity. We begin speaking of the extra dimensions models that preceded the Randall Sundrum model: Kaluza Klein, Arkani-Hammed- Dimopoulus-Dvali (ADD) and the Rubakov’s model ( The universe as a domain wall). Then, we make a review of the Lisa Randall and Ramman Sundrum papers. After that,we focus on the problem of the stabilization of the radius. This problem arises in the type I model. Lastly, we explain the solution that was created to it: The Goldberger Wise mechanism. / Nessa dissertação estudamos os modelos Randall Sundrum Tipos I e II e a estabilização do raio da dimensão extra. Tanto o tipo I quanto o II foram elaborados por Lisa Randall e Ramman Sundrum. O tipo I foi desenvolvido para resolver o problema da hierarquia de gauge ( grande discrepância entre a escala de energia do modelo padrão (103 GeV ) e a escala de energia da gravidade (1019 GeV ) . O tipo II trata, detalhadamente, o comportamento da gravidade. Iniciamos falando dos modelos de dimensões extra que antecederam os modelos de Randall Sundrum: Kaluza-Klein, Arkani-Hamed-DimopoulosDvali (ADD) e o modelo de Rubakov (O Universo como uma parede de domínio). Em seguida, fazemos uma revisão dos trabalhos de Lisa Randall e Ramman Sundrum. Após isso, focamos no problema da estabilização do raio. Esse problema surge no modelo tipo I. Por fim, explicamos a solução dada para ele: O mecanismo de Goldberger Wise.

Since the discovery of the Higgs boson in 2012, the search for new physics beyond the Standard Model has been greatly intensified. At the CERN Large Hadron Collider (LHC), ATLAS searches for new physics entail looking for new particles by colliding protons together. Presented here is a search for a new form of quark matter called Vector-like Quarks (VLQ), which are hypothetical particles that are expected to have mass around a few TeV. VLQ can come in a variety of forms and can couple to their Standard Model (SM) quark counterparts, particularly to the third generation. They are necessary in several beyond the SM theories in order to solve the hierarchy problem. This search uses 36.1 fb−1of proton-proton collision data collected with the ATLAS detector at the LHC from August 2015 to October 2016. Only events with two leptons of the same charge, or three leptons, plus b-jets and high missing transverse energy are considered in the main analysis. This signature is rarely produced in the SM, which means the backgrounds in this analysis are relatively low. This analysis is sensitive to specific predicted decay modes from pair production of an up-type VLQ with a charge of +2/3, T, an up-type VLQ with a charge of +5/3, T5/3, and a down-type quark with a charge of −1/3, B, as well as single production of T5/3. There is another theorized VLQ that this analysis is not sensitive to: B−4/3, due to its primary decay mode, which is unable to produce the final-state signature of interest. The results from this analysis suggest only a slight deviation of data from SM backgrounds reaching as high as 1.89σ, which does not indicate evidence for VLQ. A mostly frequentist statistical technique, called the CLS Method, is used to interpret the data and set limits on the T, B, and T5/3 signal models. Using this method, exclusion limits are set at the 95% confidence level, effectively excluding T mass below 0.98 TeV, T5/3 mass below 1.2 TeV, and B mass below 1.0 TeV, assuming singlet branching ratios. Also, branching ratio independent limits are set on the T and B VLQ.

No description available.

Proteases are important enzymes in the biotechnology due to their specific cleavage of substrates. HRV 3C, sortase A and TEV are some examples of cysteine proteases which become more of use lately in applications as removal of affinity tags (3C/TEV) and labelling of proteins (sortase). Here an investigation was made on the proteases by displaying them on two different prokaryotic hosts; E. coli and S. carnosus and to use these to cleave away affinity proteins (Affibody molecule) from other cells with an incorporated cleavage site. Constructs were cloned and incorporated into expressing strains which were then cultivated and induced. Analysis of surface expression was done by flow cytometer. Cleavage was made by cultivating combinations with cleavable bacteria and bacteria displaying proteases. A functional protease would lead to the presence of Affibody molecules in the supernatant. Flow cytomtery analysis was first made to inevstigate signal difference in Affibody binding by the addition of flurophores. Secondly SDS-PAGE was made on the centrifuged supernatant to investigate the presence of a product. Finally analysis of the bacteria was made by examining the reaction with soluble substrate and comparing activity with soluble enzyme. All of the enzymes were able to be displayed on the surface of bacteria with a clear separation from control. The cleavage analysis showed however varying results yet no clear evidence of product. Best flow cytometer results were seen for 3C but SDS-PAGE/MS did not show any cleaved product. For Sortase SDS-PAGE showed positive result but analysis with MS showed no product. TEV was concluded not to be funcional at all hence the failing to cleave soluble substrate  when condition seemed near optimal and faulty flow cytometer data. Even though the lack of success there is still many further studies that can be done on the proteases in order to prove its absence/presence  of activity.

Man has always been fascinated by the flight of birds and insects. First attempts at flight involved flapping wings to mimic the birds and insects that had been observed in flight. Fixed wings proved to be a more practical approach and have been used for over 100 years for manned flight. Emphasis has been placed on flapping wing designs for micro air vehicles (MAVs) as research has shown that challenges arise in lift generation and stability in fixed wing flight as the scale decreases [1].This research explores the use of 3D, time-resolved, Synthetic Aperture PIV (SAPIV) in measuring flow velocities on the mechanical flapping wing of a MAV in tethered flight. The vortical structures on the MAV are measured using both SAPIV and 2DPIV to be able to analyze 2D and 3D velocity fields. The 3D vorticity plots and 2D slice vorticity plots show the three-dimensional nature of the Leading Edge Vortex (LEV) and Trailing Edge Vortex (TEV). 2DPIV plots and 2D slices from the 3D data show general agreement in the structure and behavior of the flow around the flapping wing. The lift and thrust generated by the MAV are measured using a force gauge. The wing tip is tracked in 2D and 3D for synchronization of the measured lift forces with the flow field measurements from the SAPIV. The positive and negative circulation are plotted against the measured lift and thrust forces. The measured lift and thrust forces from the force gauge are then compared to the calculated lift and thrust forces from the measured 3D circulation found through the SAPIV flow field measurements. A plane measured parallel to the LEV and TEV vortex cores allows the defining of a unit vector that is directed normal to the top of the wing and the LEV and TEV cores. The decomposition of the unit vector allows for the calculation of the lift and thrust generated by the circulation around the wing. The comparisons between the measured and calculated forces show good agreement in the case of the measured and calculated lift forces.

Le détecteur ATLAS est une expérience généraliste de physique des particules situéeà un point de collision du LHC, au CERN. Le détecteur est complet et opérationneldepuis juin 2008. La mise en oeuvre du système calorimétrique a alors été possible,grâce notamment à l’étude de la variable "énergie transverse manquante". Cettevariable, indispensable aux mesures de précision du Modèle Standard et à larecherche de Nouvelle Physique, a ainsi pu être testée pour la première fois in situ. Ledétecteur était prêt et a montré de bonnes performances lors des premières collisionsdu LHC à la fin de l’année 2009, en particulier avec l’étude de données dites de biaisminimum. Avec les données de collisions, il a également été possible d’étudier desperformances des électrons, notamment leurs variables d’identification, et la compréhension de la matière avant le calorimètre.Les premières collisions à une énergie de 7 TeV dans le centre de masse en 2010 ontpermis d’étudier les propriétés des bosons W produits lors de ces collisions. Aprèsseulement quelques mois de prise de données, l’on a pu observer et mesurer la section efficace de production de cette particule. L’enjeu principal de cette mesure aété l’estimation des erreurs systématiques dues à l’électron et à l’énergie transversemanquante. Avec toutes les données enregistrées en 2010, l’asymétrie de charge duboson W a également pu être mesurée. Cette mesure est importante pour ladétermination des fonctions de distribution de partons dans le proton, donnéesindispensables à la bonne compréhension des collisions hadroniques au LHC. / The ATLAS detector is a multi-purpose experiment located at one of the collisionpoints of the LHC, at CERN. The detector is complete and in the acquisition since June2008. I’ve been working since then on the commissioning of the calorimeter system, inparticular thanks to the study of the “missing transverse energy” variable. Thisvariable is essential for precision measurements of the Standard Model, and for thesearch of New Physics ; it was tested in situ for the first time. The detector are readyfor the first LHC collisions at the end of 2009, and showed good performances, inparticular in the study of minimum bias events. I also participated to the study of theelectron performances, more particularly working on the identification variables andon the material before the calorimeter.The first collisions at a centre-of-mass energy of 7 TeV allowed me to study theproperties of W bosons. I participated to the observation and to the measurement ofthe production cross-section of this particle, taking part in particular in theassessment of the uncertainties due to the missing transverse energy. With all thedata recorded in 2010, I took part in the measurement of the W boson chargeasymmetry. This measurement is important for the determination of the partondistribution functions of the proton, which are of utmost importance for theunderstanding of hadronic collisions at the LHC.