Dissertations / Theses on the topic 'Vector coupling'

A greater understanding of precessional dynamics in magnetic systems is central to several emerging technologies. This thesis presents the design, construction and development of a Vector Network Analyser based Ferromagnetic Resonance measurement instrument (VNA-FMR), and its application in characterising dynamic material properties in hybrid anisotropy [CoPd]8-NiFe films, produced by remote plasma sputtering. Potential applications for hybrid films include Spin Torque Oscillators (STOs) or Vortex Oscillators (VO) for use as microwave emitters in, for example in Microwave Assisted Magnetic Recording (MAMR). The VNA-FMR system was first used to measure thin films of NiFe (permalloy) which allowed its capabilities to be quantified and compared to systems reported in the literature. The instrument demonstrated the capability of measuring permalloy films down to a thickness of 3 nm and was used to measure resonance and damping behaviour which agreed well with theory. The results obtained forMs were in agreement with measurement using Vibrating Sample Magnetometry. The effect of interlayer exchange on FMR was explored in hybrid films using a sample series with varying Pd spacer layer thickness, t, [Co/Pd]-Pd(t)-NiFe. As Pd spacer thickness increased, a transition was observed from near complete coupling with a single resonance mode to separate acoustic and optical branches of resonance. As spacing was further increased, the branches converged towards the resonances of the individual component layers of the hybrid films. The results suggest exchange coupling has a range of less than 2 nm, and is completely extinguished at 5 nm, in agreement with previous measurements. However, a change in damping behaviour was observed between 10 and 20 nm spacer thickness, independent of field orientation.

Pour lutter contre le changement climatique, l'Europe s'est engagée à ce que son système énergétique soit décarboné d'ici 2050.Le système électrique présente un important potentiel de décarbonation. Il peut ainsi contribuer à la décarbonation d'autres vecteurs (hydrogène par exemple), qui auront donc tendance à s'électrifier davantage. Cette thèse s'est donc concentrée d’une part sur la décarbonation du système électrique, et d’autre part sur l'interaction entre les différents vecteurs énergétiques. La décarbonation du vecteur électrique reposera sur l'utilisation des énergies renouvelables. Or, les études qui évaluent leur potentiel obtiennent des valeurs très différentes. Dans le premier chapitre, à travers une revue systématique de la littérature des études de potentiel éolien et photovoltaïque en Europe, la variabilité de ces valeurs a été examinée. Ce chapitre montre que les limites surfaciques des potentiels ne sont pas restrictives, et la variabilité des valeurs est due à l'ajout de critères socio-politiques dans les calculs de potentiel. In fine, la limite au développement des énergies renouvelables ne sera pas la faisabilité technique mais la volonté politique et sociétale et les contraintes du secteur industriel, y compris la disponibilité des ressources naturelles nécessaires, comme les métaux par exemple. Dans un deuxième chapitre, le fonctionnement et les prix du système énergétique couplé, à capacités fixes, ont été étudiés. L'influence des couplages sur les prix des vecteurs énergétiques a été soulignée. En particulier, la flexibilité de la demande en gaz de synthèse (via l'électrolyse) pourrait fixer les prix de l'électricité sur une majorité des pas de temps de l'année. De plus, l’importance de la gestion saisonnière des stocks dans la formation des prix du gaz, et donc de l'électricité, a été mise en évidence. Par ailleurs, pour fonctionner de manière optimale, un tel système nécessite un haut niveau de coordination entre les vecteurs : les variantes qui dégradent la coordination montrent une augmentation significative des coûts d'exploitation du système énergétique. Enfin, un troisième chapitre a traité des conséquences des couplages énergétiques sur les besoins en flexibilité du système. Des variantes sur chaque vecteur ont été analysées à travers l'évaluation des besoins en flexibilité via des indicateurs sur plusieurs échelles de temps. En particulier, l'intérêt de la coordination entre les vecteurs a été confirmé : elle permet aussi d'éviter des investissements massifs
To address climate change, Europe is committed to a decarbonized energy system by 2050.The power system has a large potential for decarbonization. It can thus contribute to the decarbonization of other vectors (hydrogen for example), which will therefore tend to become more electrified. Therefore, this thesis has focused on the decarbonization of the power system on the one hand, and the interaction between the various energy vectors on the other.The decarbonization of the power vector will involve the use of renewable energies. However, the studies that evaluate their potential obtain very different values. In the first chapter, which consisted of a systematic literature review of wind and photovoltaic studies of potential in Europe, the variability of these values was examined. The areal limits of the potentials are not restrictive, and the variability of the values is due to the addition of socio-political criteria to the calculations of potential. Ultimately, the limit to the development of renewables will not be technical feasibility but political and societal will and limits of the industrial sector, including the availability of the necessary natural resources (metals, etc.).In a second chapter, the operation and prices of this coupled system with fixed capacities were studied. The influence of the couplings on the prices of the energy vectors was underlined. In particular, the flexibility of the demand for synthesis gas (via electrolysis) could set the electricity prices on a majority of the time steps of the year. The importance of seasonal stock management in the formation of gas prices, and therefore electricity prices, was highlighted. To operate optimally, such a system requires a high level of coordination between vectors. Variants that degrade coordination show a significant increase in the operating costs of the energy system.Finally, a third chapter addressed the consequences of energy couplings on the system flexibility requirements. Variants on each vector were analyzed through the evaluation of the flexibility needs based on indicators on several time scales. In particular, the interest of coordination between vectors was confirmed: it also avoids massive investments

The primary objective of this dissertation is to present a clear physical picture and useful insights of polarization effects in the diffraction of focused beams by grooved, multilayer-coated disks. The reading process of optical disk systems significantly relies on the reaction of the incident focused beam to the disk structure, may it be the groove profile or coating materials. The resulting complex-amplitude from diffraction is the main source for the readout signal. In the presence of the periodic pattern and the focused beam, however, different polarization states usually result in different complex-amplitudes. A good understanding of polarization effects in grooved multilayer disks is thus required for the optimum design of optical data storage systems. The pursuit of high-density recording inevitably drives the optical data storage industry to reduce the wavelength of light sources, decrease the track pitch of optical disks, and increase the numerical aperture of objective lenses. The track pitch and the size of the focused spot gradually approach the optical wavelength. Under these circumstances, the analysis of the interaction of focused beams with this type of high-frequency periodic disk using conventional scalar diffraction theory is no longer adequate. Only through vector diffraction study of polarization effects in the interaction of the focused beam with the periodic pattern can the characteristics of an optical disk system be fully understood and improved. Starting from the introduction of various polarization effects in optical disk systems and basic concepts of both scalar and vector diffraction theory, we then focus on the studies of diffraction patterns at the exit pupil of the objective lens and on the disk surface. Different behavior on the baseball pattern and in the effective groove depth is observed for the two polarization states. The use of the solid immersion lens to extensively increase the area density of optical disk systems prompts us to investigate the influence of evanescent-wave coupling on the near-field optical disk system. Finally, we study the feasibility of using a novel differential polarization microscope to reduce polarization effects and to increase the image contrast of magnetic domains on magneto-optical disks.

The role of scalar mesons in radiative vector meson decays is investigated. The effects of scalar-isoscalar f_{0}(980) and scalar-isovector a_{0}(980) mesons are studied in the mechanism of the radiative Phi->
pi{+}pi{-}gamma and phi->
pi{0}eta gamma decays, respectively. A phenomenological approach is used to study the radiative phi->
pi{+}p{-}gamma decay by considering the contributions of sigma-meson, rho-meson and f_{0}-meson. The interference effects between different contributions are analyzed and the branching ratio for this decay is calculated. The radiative phi->
pi{0}eta gamma decay is studied within the framework of a phenomenological approach in which the contributions of rho-meson, chiral loop and a_{0}-meson are considered. The interference effects between different contributions are examined and the coupling constants g_{phi a_{0} gamma} and g_{a_{0}K{+}K{-}} are estimated using the experimental branching ratio for the phi->
pi{0}eta gamma decay. Furthermore, the radiative rho{0}pi{+}pi{-}gamma$ and rho{0}->
pi{0}pi{0}gamma decays are studied to investigate the role of scalar-isoscalar sigma-meson. The branching ratios of the rho{0}->
pi{+}pi{-}gamma and rho{0}->
pi{0}pi{0}gamma decays are calculated using a phenomenological approach by adding to the amplitude calculated within the framework of chiral perturbation theory and vector meson dominance the amplitude of sigma-meson intermediate state. In all the decays studied the scalar meson intermediate states make important contributions to the overall amplitude.

The goal of the original research presented in this thesis is to study the strong coupling regime of Quantum Field Theories (QFTs) with different methods, making concrete predictions about the phase structure and the dynamics of these theories, and on their observables. The focus is on (gauge) field theories in three spacetime dimensions, which are an interesting laboratory to understand the properties of strong coupling in setups that are usually simpler than in the more familiar case of gauge theories in four dimensions. Importantly, topological effects play a relevant role in three dimensions, thanks to the presence of the so-called Chern-Simons term.The thesis contains a short introduction to QFTs in 3d, principles and applications of infrared dualities, large N techniques, and holography. Indeed, the web of infrared dualities, the large N expansion, and the holographic correspondence between QFT and gravity are the main tools which we use to investigate the strongly coupled regimes of 3d QFTs.Then, the original material is presented. In a first line of research, we focus on the study of the phase diagram of a 3d gauge theory making use of conjectured infrared dualities, extending such dualities to the case where more than one mass parameter can be dialed. In a second line of research, we study a class of 3d gauge theories by engineering their gravity dual in a string theory setup. We prove the existence of multiple phase transitions between phases characterized by both massless particles and topological sectors. In a third line of research, we use holography as a tool to explore the interplay between the physics of 4d QCD and 3d gauge theories. In particular, we analyze the properties of 3d domain walls, which appear as soliton-like solutions of 4d QCD in specific parametric regimes. Finally, we propose a boundary construction of 3d large N vector models, which appear as critical points of theories obtained by coupling degrees of freedom localized on a 3d boundary to a 4d bulk theory. This construction allows to prove new dualities and uncovers a new computational tool for 3d vector models.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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Dans ce document deux analyses des propriétés du boson de Higgs se désintégrant en 2 photons dans l'expérience CMS située auprès du LHC (Large Hadron Collider) sont présentées.Le document commence par une introduction théorique sur le Modèle Standard et sur la physique du boson de Higgs, suivie par une description détaillée de l'expérience CMS. En deuxième lieu, les algorithmes de réconstruction et identification des photons sont présentés, avec une attention particulière aux différences entre le premier et le deuxième run du LHC, le premier run (Run1) ayant été pris entre 2010 et 2012 avec une énergie dans le centre de masse de 7 puis 8 TeV, le deuxième (Run2) ayant commencé en 2015 avec une énergie dans le centre de masse de 13 TeV. Les performances des reconstructions du Run 1 et du Run 2 en ce qui concerne l'identification des photons sont comparées. Ensuite l'algorithme d’identification des photons pour l'analyse H->γγ et optimisé pour le Run2 est présenté. Pour ce faire une méthode d'analyse multivariée est utilisée. Les performances de l'identification des photons à 13 TeV sont enfin étudiées et une validation donnée-simulation est effectuée.Ensuite l'analyse H->γγ avec les premières données du Run2 est présentée. Les données utilisées correspondent à une luminosité intégrée de 12.9 fb⁻¹. Une catégorisation des événements est faite, afin de rendre maximale la signification statistique du signal et d’étudier les différents modes de production du boson de Higgs. La signification statistique observée pour le boson de Higgs du Modèle Standard est 1.7 sigma, pour une signification attendue de 2.7 sigma.Enfin une étude de faisabilité ayant pour but de contraindre les couplages anomaux du boson de Higgs aux bosons de jauges est présentée. Pour cette analyse les données à 8 TeV collectées pendant le Run 1 du LHC, correspondant a' une luminosité intégrée de 19.5/fb sont utilisées. Cette analyse exploite la production du boson de Higgs par fusion de bosons-vecteurs (VBF), avec le Higgs se désintégrant ensuite en 2 photons. Les distributions cinématiques des jets et des photons, qui dépendent de l'hypothèse de spin-parité, sont utilisées pour construire des discriminants capables de séparer les différentes hypothèses de spin-parité. Ces discriminants permettent de définir différentes régions de l'espace des phases enrichies en signal de différentes spin-parité. Les différents nombres d’événements de signal sont extraits dans chaque région par un ajustement de la masse invariante diphoton, permettant de déterminer les contributions respectives des différents signaux et permettant ainsi de contraindre la production de boson de Higgs pseudo-scalaire (spin-parité 0-)
In this document two analyses of the properties of the Higgs boson in the diphoton decay channel with the CMS experiment at the LHC (Large Hadron Collider) are presented.The document starts with a theoretical introduction of the Standard Model and the Higgs boson physics, followed by a detailed description of the CMS detector.Then, photon reconstruction and identification algorithms are presented, with a particular focus on the differences between the first and the second run of the LHC, the first run (Run1) took place from 2010 to 2012 with a centre-of-mass energy of 7 and then 8 TeV, while the second run (Run2) started in 2015 with a centre-of-mass energy of 13 TeV. Performances of Run1 and Run2 reconstructions from the photon identification point of view are compared. Then the photon identification algorithm for the H->γγ analysis optimised for Run2 is presented. To do that a multivariate analysis method is used. Performances of the photon identification at 13 TeV are finally studied and a data-simulation validation is performed.Afterwards, the H->γγ analysis using the first Run2 data is presented. The analysis is performed with a dataset corresponding to an integrated luminosity of 2.7/fb. An event classification is performed to maximize signal significance and to studyspecific Higgs boson production modes. The observed significance for the standard model Higgs boson is 1.7 sigma, while a significance of 2.7 sigma is expected.Finally a feasibility study, having the aim of constraining the anomalous couplings of the Higgs boson to the vector bosons, is presented. This analysis is performed using the data collected at 8 TeV during Run1 at the LHC, corresponding to an integrated luminosity of 19.5/fb. This analysis exploits the production of the Higgs boson through vector boson fusion (VBF), with the Higgs decaying to 2 photons. The kinematic distributions of the dijet and diphoton systems, which depend from the spin-parity hypothesis, are used to build some discriminants able to discriminate between different spin-parity hypotheses. These discriminants allow to define different regions of the phase-space enriched with a certain spin-parity process. The Higgs boson signal yield is extracted in each region from a fit to the diphoton mass, allowing to determine the contributions of the different processes and then constrain the production of a pseudo-scalar (spin-parity 0-) Higgs boson

Electroweak gauge bosons as central components of the Standard Model of particle physics are well understood theoretically and have been studied with high precision at past and present collider experiments. The electroweak theory predicts the existence of a scattering process of these particles consisting of contributions from triple and quartic bosonic couplings as well as Higgs boson mediated interactions. These contributions are not separable in a gauge invariant way and are only unitarized in the case of a Higgs boson as it is described by the Standard Model. The process is tied to the electroweak symmetry breaking which introduces the longitudinal modes for the massive electroweak gauge bosons. A study of this interaction is also a direct verification of the local gauge symmetry as one of the fundamental axioms of the Standard Model. With the start of the Large Hadron Collider and after collecting proton-proton collision data with an integrated luminosity of 20.3/fb at a center-of-mass energy of 8 TeV with the ATLAS detector, first-ever evidence for this process could be achieved in the context of this work. A study of leptonically decaying WWjj, same-electric-charge diboson production in association with two jets resulted in an observation of the electroweak WWjj production with same electric charge of the W bosons, inseparably comprising WW->WW electroweak gauge boson scattering contributions, with a significance of 3.6 standard deviations. The measured production cross section is in agreement with the Standard Model prediction. In the course of a study for leptonically decaying WZ productions, methods for background estimation, the extraction of systematic uncertainties and cross section measurements were developed. They were extended and applied to the WZjj final state whereof the purely electroweakly mediated contribution is intrinsically tied to the scattering of all Standard Model electroweak gauge bosons: Wγ->WZ and WZ->WZ. Three charged leptons and a neutrino from the decay of the final state bosons allow inferences about the scattering process. A distinct signature is provided by the two accompanying tagging jets as remnants of the incoming quarks radiating the initial electroweak gauge bosons. The cross section of the electroweak WZjj production was measured to σ(fiducial, observed) = (0.63 +0.32 -0.28 (stat.) +0.41 -0.24 (syst.)) fb and was found to be consistent with the Standard Model prediction at next-to-leading order in perturbative quantum chromodynamics, σ(fiducial, theory) = (0.31 +0.03 -0.05) fb. Unfolded differential cross sections of kinematic variables sensitive to models of new physics were derived. Anomalous quartic electroweak gauge couplings are introduced as dimensionless coupling parameters of additional operators within an effective field theory approach. Constraints on the parameters of operators with dimension eight were set employing a unitarization prescription based on form factors.

Un code de calcul utilisant la méthode des éléments finis nodaux a été développé. Ce logiciel permet de simuler, en trois dimensions, les machines électriques tournantes. Les phénomènes magnétiques sont calculés par une formulation en potentiel vecteur magnétique A. Pour modéliser les moteurs électriques quel que soit leur fonctionnement, nous utilisons une résolution en régime transitoire avec couplage de l'équation générale de la mécanique. Une méthode de prise en compte du mouvement et plus généralement des limites a été étudiée et utilisée dans le logiciel. Des conditions aux limites de type champ tangentiel, champ normal, symétrie et périodicité (cyclique, anti-cyclique) ont été implémentées. Des maillages tridimensionnels spécifiques aux machines tournantes ont été construits afin de remédier au manque de puissance des systèmes informatiques actuels (1994). Afin de réduire les temps de résolution, inhérents à la méthode de résolution en pas à pas dans le temps tridimensionnel, nous avons pris soin d'optimiser le logiciel dans sa structure général et dans chacune de ses routines de calcul. Le logiciel a été validé sur l'étude d'un moteur à courant continu ainsi que sur un moteur à réluctance variable

Due to the ever-increasing worldwide consumption of memory for digital information, new technologies for higher capacity and faster data storage systems have been the focus of research and development. A step towards achieving higher data storage densities or magnetic recording media is the concept of bit patterned media, where the magnetic recording layer is divided up into magnetically isolated bit units. This approach is one of the most promising technologies for increasing data storage densities and could be implemented by nanostructuring the wafer. Therefore, the fabrication of the appropriate nanostructures on a small scale and then be able to manufacture these structures on an industrial scale is one of the problems where science and industry are working on a solution. In addition, the answer to the open question about the influence that patterning on the nano length scale has on the magnetic properties is of great interest. The main goal of this thesis is to answer the open question, which magnetic properties can be tailored by a modification of the surface texture on the nanometre length scale. For this purpose the following properties: anisotropy, remanence, coercivity, switching field distribution, saturation magnetisation, Gilbert damping, and inhomogeneous linebroadening were compared between planar two dimensional thin ferromagnetic films and three dimensional magnetic structures. In addition, the influences of the tailored morphology on the intergranular or the exchange coupling between the structures, which is called interdot exchange coupling, was investigated. For the ferromagnetic thin films, the focus of the investigations was on the granular CoCrPt:SiO2 and [Co/Pd] layer, which currently are the state-of-the-art material for magnetic data storage media. These materials are characterised by their high coercivity and high perpendicular anisotropy, which has a low spatial distribution in the preferred direction of magnetisation. In this work the pre-structured GaSb(001) substrate with self-assembled periodic nanocone structures at the surface are used. The preparation by ion beam erosion of these structures is simple, fast, and highly reproducible and therefore this method is particularly beneficial for fundamental research. To compare the 2D thin films with the 3D magnetic structures, besides the pre-structured specimen, planar samples were also fabricated. The first sample series prepared was coated by Py. Due to the fact that the magnetic properties of this material are well-known, it was also possible to do some OOMMF simulations in addition to the VNA-FMR and MOKE measurements. Afterwards two planar samples with CoCrPt and CoCrPt:SiO2 were prepared. The planar CoCrPt:SiO2 samples were Co+ ion implanted to study the influence of such irradiation on the intergranular and interdot exchange coupling, switching field distribution, and in particular on the spin dynamics. Moreover, both samples were measured by TRMOKE in order to obtain information about the spin dynamics. Subsequently, the perpendicular storage media materials CoCrPt:SiO2 and [Co/Pd] were deposited on a prestructured GaSb(001) nanocone substrate surface. These sample series were measured by MOKE, SQUID, and vector-VSM. The measurements demonstrate the influence of the periodicity and height of the nanocones on the intergranular and interdot exchange coupling. They also show the reorientation of the magnetisation with respect to the curvature of the substrate template and furthermore, the morphology-induced influences on the magnetic domains. From the comparison between the results for the planar and the pre-structured samples, a decrease of the interdot exchange coupling was observed, which scales together with the periodicity of the nanocone pattern. In addition, it was shown that for all samples with thin magnetic films on nanocones,the magnetisation aligns along the curvature of the underlying nanocone structure. For Py on nanocones, planar granular CoCrPt:SiO2, and planar granular CoCrPt, measurements by VNA-FMR and TRMOKE could be carried out, which yielded information about the spin dynamics. The results obtained for both of the planar sample are comparable to values from the literature for the Gilbert damping. The results for the Py samples showed that the commonly used 2D model resonance condition is, in case of a 3D magnetic structure, no longer valid due to the alignment of the magnetisation along the underlying substrate structure and therefore an new model has to be derived
Aufgrund des weltweiten, immer weiter steigenden Bedarfs an Speicherplatz von digitalen Information, sind neue Technologien für größere und schnellere Speichermedien im Fokus von Forschung und Entwicklung. Ein Schritt hin zu einer höheren Speicherdichte in der magnetischen Datenspeicherung ist dabei das sogenannte Konzept der ”Bit patterned media”, das definierte Informationseinheiten auf regelmäßig angeordneten Nanostrukturen beschreibt. Dieser Ansatz ist einer der derzeit vielversprechendsten Optionen die Speicherdichte zu erhöhen. Dabei ist die Herstellung der benötigten Nanostrukturen und deren Skalierung hin zu makroskopischen Dimensionen eines der Probleme an deren Lösung die Wissenschaft und Industrie derzeit arbeitet. Desweiteren ist die Antwort auf die noch offene Frage nach der Beeinflussung der nanoskaligen Strukturen auf die magnetischen Eigenschaften von großem Interesse. Das Hauptziel in dieser Arbeit ist es, einen Beitrag zur Beantwortung der Frage, welche magnetischen Eigenschaften sich durch eine Veränderung der Oberflächenstruktur im Nanometerbereich beeinflussen lassen, zu leisten. Hierzu wurden die folgenden Eigenschaften, wie zum Beispiel die Anisotropie, Remanenz,Koerzitivität, Schaltfeldverteilung, Sättigungsmagnetisierung, Gilbertdämpfung und inhomogene Linienverbreiterung von planaren zweidimensionalen dünnen ferromagnetische Schichten mit denen von dreidimensionalen magnetischen Strukturen verglichen. Zusätzlich wurde der Einfluss der angegpassten Morphologie auf die intergranularen- beziehungsweise auf die zwischen den Strukturen wirkende (interdot) Austauschkopplung untersucht. Der Hauptaugenmerk bei den ferromagnetisch dünnen Schichten lag dabei auf den granularen CoCrPt:SiO2 und [Co/Pd] Filmen, die heutzutage ein Standardmaterial für die magnetischen Speichermedien darstellen. Diese Materialien zeichnen sich durch eine hohe Koerzivität und senkrechte Anisotropie, mit geringer räumlicher Verteilung der Vorzugsrichtung der Magnetisierung, aus. Die hier vorgestellten vorstrukturierten GaSb(001) Substrate mit selbstordnenden periodischen Nanokegeln auf der Oberfläche, sind mittels Ionenstrahlerosion einfach, schnell und sehr gut reproduzierbar herzustellen. Deshalb ist diese Methode besonders für die Grundlagenforschung von Vorteil. Um einen Vergleich zwischen 2D Filmen und 3D Strukturen ziehen zu können, wurden neben den vorstrukturierten Substraten auch planare Proben beschichtet. Eine erste Versuchsreihe wurde mit einem dünnen Py Film präpariert. Da dessen magnetische Eigenschaften wohlbekannt sind, konnten neben den Untersuchungen mit VNA-FMR und MOKE auch einige OOMF Simulationen erstellt werden. Danach wurden zwei Proben mit planarem CoCrPt beziehungsweise CoCrPt:SiO2 untersucht. Bei den planaren CoCrPt:SiO2 Proben wurden außerdem noch Co+ Ionen implantiert, um deren Auswirkungen auf die intergranulare Austauschkopplung, Schaltfeldverteilung und besonders auf die Spindynamik zu bestimmen. Bei beiden Probensystemen konnte zusätzlich die Spindynamik mittels zeitaufgelöstem MOKE gemessen werden. Im Anschluss wurden die beiden senkrechten Speichermedien CoCrPt:SiO2 and [Co/Pd] auf Substraten mit Nanokegeln vorstrukturierten GaSb(001) Oberflächen abgeschieden. Diese Proben wurden mit MFM, MOKE, SQUID und Vektor-VSM vermessen. Aus den Messungen konnnten dann die Einflüsse auf die intergranulare- beziehungsweise interdot Austauschkopplung in Abhängigkeit von der Periodizität und Höhe der Nanokegel bestimmt werden, sowie die Umorientierung der Magnetisierung bezüglich der Substratkrümmung und den Morphologie induzierten Einfluss auf die magnetischen Domänen. Anhand der Vergleiche zwischen den Messungen der planaren und den vorstrukturierten Proben konnte eine Verringerung der Austauschkopplung zwischen den Strukturen gezeigt werden, die mit der Nanokegelstrukturperiodizität skaliert. Außerdem wurde in allen dünnen magnetischen Filmen auf Nanokegeln gezeigt, dass die Magnetisierung sich in Abhängigkeit der darunterliegenden Struktur ausrichtet. Bei den Py auf Nanokegeln, den planaren CoCrPt und dem planaren CoCrPt:SiO2 Proben konnten außerdem mit VNA-FMR und TRMOKE Informationen bezüglich der Spindynamik gemessen werden. Die erzielten Ergebnisse, der beiden planaren Proben, sind vergleichbar mit denen, aus der Literatur bekannten Werten, für die Gilbertdämpfung. Darüber hinaus wurde durch die Messungen an den Py Proben gezeigt, dass die Theorie, des bisher genutzten 2D Modells, nicht mehr gültig ist, da sich die Magnetisierung entlang der Substratstruktur ausrichtet, und deshalb ein neues Model aufgestellt werden muss

Due to the ever-increasing worldwide consumption of memory for digital information, new technologies for higher capacity and faster data storage systems have been the focus of research and development. A step towards achieving higher data storage densities or magnetic recording media is the concept of bit patterned media, where the magnetic recording layer is divided up into magnetically isolated bit units. This approach is one of the most promising technologies for increasing data storage densities and could be implemented by nanostructuring the wafer. Therefore, the fabrication of the appropriate nanostructures on a small scale and then be able to manufacture these structures on an industrial scale is one of the problems where science and industry are working on a solution. In addition, the answer to the open question about the influence that patterning on the nano length scale has on the magnetic properties is of great interest. The main goal of this thesis is to answer the open question, which magnetic properties can be tailored by a modification of the surface texture on the nanometre length scale. For this purpose the following properties: anisotropy, remanence, coercivity, switching field distribution, saturation magnetisation, Gilbert damping, and inhomogeneous linebroadening were compared between planar two dimensional thin ferromagnetic films and three dimensional magnetic structures. In addition, the influences of the tailored morphology on the intergranular or the exchange coupling between the structures, which is called interdot exchange coupling, was investigated. For the ferromagnetic thin films, the focus of the investigations was on the granular CoCrPt:SiO2 and [Co/Pd] layer, which currently are the state-of-the-art material for magnetic data storage media. These materials are characterised by their high coercivity and high perpendicular anisotropy, which has a low spatial distribution in the preferred direction of magnetisation. In this work the pre-structured GaSb(001) substrate with self-assembled periodic nanocone structures at the surface are used. The preparation by ion beam erosion of these structures is simple, fast, and highly reproducible and therefore this method is particularly beneficial for fundamental research. To compare the 2D thin films with the 3D magnetic structures, besides the pre-structured specimen, planar samples were also fabricated. The first sample series prepared was coated by Py. Due to the fact that the magnetic properties of this material are well-known, it was also possible to do some OOMMF simulations in addition to the VNA-FMR and MOKE measurements. Afterwards two planar samples with CoCrPt and CoCrPt:SiO2 were prepared. The planar CoCrPt:SiO2 samples were Co+ ion implanted to study the influence of such irradiation on the intergranular and interdot exchange coupling, switching field distribution, and in particular on the spin dynamics. Moreover, both samples were measured by TRMOKE in order to obtain information about the spin dynamics. Subsequently, the perpendicular storage media materials CoCrPt:SiO2 and [Co/Pd] were deposited on a prestructured GaSb(001) nanocone substrate surface. These sample series were measured by MOKE, SQUID, and vector-VSM. The measurements demonstrate the influence of the periodicity and height of the nanocones on the intergranular and interdot exchange coupling. They also show the reorientation of the magnetisation with respect to the curvature of the substrate template and furthermore, the morphology-induced influences on the magnetic domains. From the comparison between the results for the planar and the pre-structured samples, a decrease of the interdot exchange coupling was observed, which scales together with the periodicity of the nanocone pattern. In addition, it was shown that for all samples with thin magnetic films on nanocones,the magnetisation aligns along the curvature of the underlying nanocone structure. For Py on nanocones, planar granular CoCrPt:SiO2, and planar granular CoCrPt, measurements by VNA-FMR and TRMOKE could be carried out, which yielded information about the spin dynamics. The results obtained for both of the planar sample are comparable to values from the literature for the Gilbert damping. The results for the Py samples showed that the commonly used 2D model resonance condition is, in case of a 3D magnetic structure, no longer valid due to the alignment of the magnetisation along the underlying substrate structure and therefore an new model has to be derived.
Aufgrund des weltweiten, immer weiter steigenden Bedarfs an Speicherplatz von digitalen Information, sind neue Technologien für größere und schnellere Speichermedien im Fokus von Forschung und Entwicklung. Ein Schritt hin zu einer höheren Speicherdichte in der magnetischen Datenspeicherung ist dabei das sogenannte Konzept der ”Bit patterned media”, das definierte Informationseinheiten auf regelmäßig angeordneten Nanostrukturen beschreibt. Dieser Ansatz ist einer der derzeit vielversprechendsten Optionen die Speicherdichte zu erhöhen. Dabei ist die Herstellung der benötigten Nanostrukturen und deren Skalierung hin zu makroskopischen Dimensionen eines der Probleme an deren Lösung die Wissenschaft und Industrie derzeit arbeitet. Desweiteren ist die Antwort auf die noch offene Frage nach der Beeinflussung der nanoskaligen Strukturen auf die magnetischen Eigenschaften von großem Interesse. Das Hauptziel in dieser Arbeit ist es, einen Beitrag zur Beantwortung der Frage, welche magnetischen Eigenschaften sich durch eine Veränderung der Oberflächenstruktur im Nanometerbereich beeinflussen lassen, zu leisten. Hierzu wurden die folgenden Eigenschaften, wie zum Beispiel die Anisotropie, Remanenz,Koerzitivität, Schaltfeldverteilung, Sättigungsmagnetisierung, Gilbertdämpfung und inhomogene Linienverbreiterung von planaren zweidimensionalen dünnen ferromagnetische Schichten mit denen von dreidimensionalen magnetischen Strukturen verglichen. Zusätzlich wurde der Einfluss der angegpassten Morphologie auf die intergranularen- beziehungsweise auf die zwischen den Strukturen wirkende (interdot) Austauschkopplung untersucht. Der Hauptaugenmerk bei den ferromagnetisch dünnen Schichten lag dabei auf den granularen CoCrPt:SiO2 und [Co/Pd] Filmen, die heutzutage ein Standardmaterial für die magnetischen Speichermedien darstellen. Diese Materialien zeichnen sich durch eine hohe Koerzivität und senkrechte Anisotropie, mit geringer räumlicher Verteilung der Vorzugsrichtung der Magnetisierung, aus. Die hier vorgestellten vorstrukturierten GaSb(001) Substrate mit selbstordnenden periodischen Nanokegeln auf der Oberfläche, sind mittels Ionenstrahlerosion einfach, schnell und sehr gut reproduzierbar herzustellen. Deshalb ist diese Methode besonders für die Grundlagenforschung von Vorteil. Um einen Vergleich zwischen 2D Filmen und 3D Strukturen ziehen zu können, wurden neben den vorstrukturierten Substraten auch planare Proben beschichtet. Eine erste Versuchsreihe wurde mit einem dünnen Py Film präpariert. Da dessen magnetische Eigenschaften wohlbekannt sind, konnten neben den Untersuchungen mit VNA-FMR und MOKE auch einige OOMF Simulationen erstellt werden. Danach wurden zwei Proben mit planarem CoCrPt beziehungsweise CoCrPt:SiO2 untersucht. Bei den planaren CoCrPt:SiO2 Proben wurden außerdem noch Co+ Ionen implantiert, um deren Auswirkungen auf die intergranulare Austauschkopplung, Schaltfeldverteilung und besonders auf die Spindynamik zu bestimmen. Bei beiden Probensystemen konnte zusätzlich die Spindynamik mittels zeitaufgelöstem MOKE gemessen werden. Im Anschluss wurden die beiden senkrechten Speichermedien CoCrPt:SiO2 and [Co/Pd] auf Substraten mit Nanokegeln vorstrukturierten GaSb(001) Oberflächen abgeschieden. Diese Proben wurden mit MFM, MOKE, SQUID und Vektor-VSM vermessen. Aus den Messungen konnnten dann die Einflüsse auf die intergranulare- beziehungsweise interdot Austauschkopplung in Abhängigkeit von der Periodizität und Höhe der Nanokegel bestimmt werden, sowie die Umorientierung der Magnetisierung bezüglich der Substratkrümmung und den Morphologie induzierten Einfluss auf die magnetischen Domänen. Anhand der Vergleiche zwischen den Messungen der planaren und den vorstrukturierten Proben konnte eine Verringerung der Austauschkopplung zwischen den Strukturen gezeigt werden, die mit der Nanokegelstrukturperiodizität skaliert. Außerdem wurde in allen dünnen magnetischen Filmen auf Nanokegeln gezeigt, dass die Magnetisierung sich in Abhängigkeit der darunterliegenden Struktur ausrichtet. Bei den Py auf Nanokegeln, den planaren CoCrPt und dem planaren CoCrPt:SiO2 Proben konnten außerdem mit VNA-FMR und TRMOKE Informationen bezüglich der Spindynamik gemessen werden. Die erzielten Ergebnisse, der beiden planaren Proben, sind vergleichbar mit denen, aus der Literatur bekannten Werten, für die Gilbertdämpfung. Darüber hinaus wurde durch die Messungen an den Py Proben gezeigt, dass die Theorie, des bisher genutzten 2D Modells, nicht mehr gültig ist, da sich die Magnetisierung entlang der Substratstruktur ausrichtet, und deshalb ein neues Model aufgestellt werden muss.

L'objet de ce travail a principalement consisté en l'étude et la mise en oeuvre d'une méthode de calcul des gradients des fonctions aérodynamiques par rapport à des paramètres géométriques pour un système aéroélastique soumis à un écoulement lointain stationnaire. Dans un premier temps, une méthodologie de calcul de l'équilibre aéroélastique statique a tout d'abord été développée. Dans ce cadre, le comportement du fluide peut être modélisé par les équations d'Euler ou par les équations de Navier-Stokes moyennées (RANS). Celles-ci sont numériquement résolues par elsA - code de simulation numérique pour la mécanique des fluides développé à l'ONERA. Le comportement de la structure est, quant à lui, prédit par la théorie des poutres et les équations d'Euler-Bernoulli. Le chargement aérodynamique est transmis à la structure par l'intermédiaire de la matrice des coefficients d'influence également appelée matrice de flexibilité. Seuls les efforts de torsion et de flexion sont transmis de manière consistante à la structure, dont seuls les mouvements induits de torsion et de flexion sont calculés sous l'hypothèse des petits déplacements. La déformation résultante sur le maillage du domaine fluide est prédite analytiquement par analogie avec la mécanique du solide. Enfin, le système aéroélastique couplé est résolu selon un processus itératif inspiré de la méthode du point fixe. Dans un deuxième temps, un cadre de calcul, pour le système aéroélastique décrit précédemment, des gradients des fonctions d'intérêt (objectif et contraintes) par rapport à un vecteur de paramètres géométriques de la forme solide a été mis en oeuvre. Les gradients peuvent être calculés par la méthode de l'équation linéarisée discrète ou par la méthode du vecteur adjoint discret. Ces méthodes reposent sur la résolution de systèmes linéaires couplés, effectuée, dans le cadre de cette étude, par un processus itératif doublement retardé. Pour finir, ces développements ont été appliqués au calcul des gradients des coefficients aérodynamiques de traînée et de portance par rapport à un ensemble de paramètres de forme pour trois configurations aérodynamiques de complexité croissante: équations d'Euler résolues sur un maillage multibloc coïncident, équations RANS résolues sur un maillage monobloc, et, finalement, équations RANS résolues sur un maillage multibloc non-coïncident. La validité des résultats a été établie par comparaison aux gradients calculés par différences finies. Une dernière partie du travail a été consacrée à l'évaluation des performances de quatre modèles réduits non physiques dans le cadre d'un processus d'optimisation de forme d'une configuration bidimensionnelle de turbomachine.

L’objet de ce travail a consisté en l’étude et la mise en oeuvre d. Une méthodede calcul des dérivées des fonctions d’intérêt d’un problème d’optimisation de forme par rapport aux paramètres géométriques décrivant la forme solide, appelées de façon générique gradients. . , pour un système aéroélastique soumis à un écoulement lointain stationnaire. Une méthodologie de calcul de l’équilibre aéroélastique statique a tout d. Abord été développée dans le cadre de laquelle le comportement du fluide peut être modélisé par les équations d’Euler ou de Navier-Stokes moyennées (RANS), résolues numériquement par elsA, code de simulation numérique pour la mécanique des fluides développé à l’ONERA, et le comportement de la structure est prédit par la théorie des poutres (équations d’Euler-Bernoulli écrites en formulation matrice de lexibilité). Un cadre de calcul des gradients relatifs à ce système a ensuite pu être mis en place. Ceux-ci sont calculés de manière analytique en utilisant, soit la méthode de l’équation linéarisée discrète, soit la méthode du vecteur adjoint discret. Ces méthodes impliquent la résolution de systèmes linéaires couplés effectuée, dans le cadre de cette étude, par un processus itératif doublement retardé. Enfin, ces développements ont été appliqués au calcul des gradients des coefficients aérodynamiques de traînée et de portance par rapport à un ensemble de paramètres de forme pour trois configurations de complexité croissante, et validés par comparaison aux valeurs des gradients calculés par différences finies. Une dernière partie de ce travail a été consacrée à l’évaluation des performances de quatre modèles réduits non physiques dans le cadre d’un processus d’optimisation de forme d’une configuration bidimensionnelle de turbomachine
This work is mainly dedicated to the sensitivity analysis of a static aeroelastic system with respect to design parameters governing its jig-shape. First, a framework able to predict the static aeroelastic equilibrium has been set up. The fluid behavior can be governed either by the nonlinear Euler equations or by the Navier-Stokes Reynolds averaged (RANS) equations. They are numerically solved by an ONERA CFD solver: elsA. The structural behavior is governed by the Euler-Bernoulli equations within the context of beam theory. The aerodynamic loads are transferred to the structure using the matrix of the influence coefficients, also called the flexibility matrix. Only the bending and the twisting aerodynamic load components are consistently transmitted to the structure, and only the bending and the torsional displacements of the structure are calculated under the small displacement hypothesis. The deformation induced on the fluid domain mesh is analytically prescribed using an analogy to solid mechanics. Finally, the resulting coupled aeroelastic system of equations is solved by an iterative process inspired from the fixed-point algorithm. Second, a framework aiming at computing the gradients of the functions of interest (objective and constraints) with respect to a vector of shape parameters related to the jig-shape of the aeroelastic system previously depicted, has been raised. These gradients can be computed either by the discrete direct differentiation method or by the discrete adjoint vector method. In both cases, a coupled linear system of equations has to be solved, which is carried out using a doubly lagged iterative process. Finally, this framework has been applied to the computation of the gradients of the drag and lift aerodynamic coefficients with respect to different shape parameters for three aerodynamic configurations of growing complexity: Euler equations solved on a multiblock mesh with matching boundaries, RANS equations on a monoblock mesh, and, at last, RANS equations solved on a multiblock mesh with non-matching boundaries. The analytical gradients have been validated through the comparison with the finite difference gradients. A last part of this work has been dedicated to the evaluation of the performances of four surrogate models within the shape optimization of a bidimensional turbomachinery configuration

The dissertation thesis deals with the investigation of the coexistence of GSM–EDGE and UMTS systems with focus on the physical layer of the systems. The aim is to provide a set of recommendations for practical cooperation while the systems operate in both the separated and the common radio bands. A detailed description of signal processing of both the systems on the physical layer is presented. On the basis of this description, models of both systems were created and implemented in the MATLAB environment. The simulations are focused on the physical layer quality parameters, especially the bit error ratio evaluation for various ratios of useful signal power to noise power during the transmission over the radio channel. Simulation is also used to examine the quality of received useful signal while it is interfered by signals from the same and adjacent channels. The purpose is to determine the isolation between these adjacent channels, when the bit error ratio of the useful signal does not exceed a certain reference value. The simulation results are subsequently subjected to comparison with the results of the experimental measurements in laboratory conditions. Before the measurements are carried out, a study of possible interference types is performed. Consequently, the crucial parameters of the measuring equipment used are verified. From the results of simulations and measurements, the proposal of a minimum and recommended carrier separation between both the systems is presented in order to efficiently utilize the assigned frequency spectrum. Furthermore, for the cooperation in both the separated and the common radio bands, the necessary precautions are given for reaching the required isolation and thereby inter-system interference minimization.

AC motors are largely used in a wide range of modern systems, from household appliances to automated industry applications such as: ventilations systems, fans, pumps, conveyors and machine tool drives. Inverters are widely used in industrial and commercial applications due to the growing need for speed control in ASD systems. Fast switching transients and the common mode voltage, in interaction with parasitic capacitive couplings, may cause many unwanted problems in the ASD applications. These include shaft voltage and leakage currents. One of the inherent characteristics of Pulse Width Modulation (PWM) techniques is the generation of the common mode voltage, which is defined as the voltage between the electrical neutral of the inverter output and the ground. Shaft voltage can cause bearing currents when it exceeds the amount of breakdown voltage level of the thin lubricant film between the inner and outer rings of the bearing. This phenomenon is the main reason for early bearing failures. A rapid development in power switches technology has lead to a drastic decrement of switching rise and fall times. Because there is considerable capacitance between the stator windings and the frame, there can be a significant capacitive current (ground current escaping to earth through stray capacitors inside a motor) if the common mode voltage has high frequency components. This current leads to noises and Electromagnetic Interferences (EMI) issues in motor drive systems. These problems have been dealt with using a variety of methods which have been reported in the literature. However, cost and maintenance issues have prevented these methods from being widely accepted. Extra cost or rating of the inverter switches is usually the price to pay for such approaches. Thus, the determination of cost-effective techniques for shaft and common mode voltage reduction in ASD systems, with the focus on the first step of the design process, is the targeted scope of this thesis. An introduction to this research – including a description of the research problem, the literature review and an account of the research progress linking the research papers – is presented in Chapter 1. Electrical power generation from renewable energy sources, such as wind energy systems, has become a crucial issue because of environmental problems and a predicted future shortage of traditional energy sources. Thus, Chapter 2 focuses on the shaft voltage analysis of stator-fed induction generators (IG) and Doubly Fed Induction Generators DFIGs in wind turbine applications. This shaft voltage analysis includes: topologies, high frequency modelling, calculation and mitigation techniques. A back-to-back AC-DC-AC converter is investigated in terms of shaft voltage generation in a DFIG. Different topologies of LC filter placement are analysed in an effort to eliminate the shaft voltage. Different capacitive couplings exist in the motor/generator structure and any change in design parameters affects the capacitive couplings. Thus, an appropriate design for AC motors should lead to the smallest possible shaft voltage. Calculation of the shaft voltage based on different capacitive couplings, and an investigation of the effects of different design parameters are discussed in Chapter 3. This is achieved through 2-D and 3-D finite element simulation and experimental analysis. End-winding parameters of the motor are also effective factors in the calculation of the shaft voltage and have not been taken into account in previous reported studies. Calculation of the end-winding capacitances is rather complex because of the diversity of end winding shapes and the complexity of their geometry. A comprehensive analysis of these capacitances has been carried out with 3-D finite element simulations and experimental studies to determine their effective design parameters. These are documented in Chapter 4. Results of this analysis show that, by choosing appropriate design parameters, it is possible to decrease the shaft voltage and resultant bearing current in the primary stage of generator/motor design without using any additional active and passive filter-based techniques. The common mode voltage is defined by a switching pattern and, by using the appropriate pattern; the common mode voltage level can be controlled. Therefore, any PWM pattern which eliminates or minimizes the common mode voltage will be an effective shaft voltage reduction technique. Thus, common mode voltage reduction of a three-phase AC motor supplied with a single-phase diode rectifier is the focus of Chapter 5. The proposed strategy is mainly based on proper utilization of the zero vectors. Multilevel inverters are also used in ASD systems which have more voltage levels and switching states, and can provide more possibilities to reduce common mode voltage. A description of common mode voltage of multilevel inverters is investigated in Chapter 6. Chapter 7 investigates the elimination techniques of the shaft voltage in a DFIG based on the methods presented in the literature by the use of simulation results. However, it could be shown that every solution to reduce the shaft voltage in DFIG systems has its own characteristics, and these have to be taken into account in determining the most effective strategy. Calculation of the capacitive coupling and electric fields between the outer and inner races and the balls at different motor speeds in symmetrical and asymmetrical shaft and balls positions is discussed in Chapter 8. The analysis is carried out using finite element simulations to determine the conditions which will increase the probability of high rates of bearing failure due to current discharges through the balls and races.

碩士
國立臺灣科技大學
電子工程系
87
Light propagates through waveguides in the form of modes. The TE and TM modes of a slab waveguide can be determined by solving the eigenvalue equation for the corresponding polarization. The modal analysis of the guided wave structure gives the modal field distribution and the propagation constant. Accurate values of the propagation constant and modal profiles are very critical for the coupling characteristics. In mode solvers there are many different techniques are investigated. We use the finite difference solution technique that based on the Alternating Direction Implicit (ADI) iterative method because of its fast convergence and minimal computer resources. This method is also adapted to the complex waveguides structure. The well-known rib semiconductor waveguides is analysed. We solve the electric field of the fundamental mode distributions of the waveguides structure, some results are compare with those other methods to confirm the accuracy of our numerical model. Optical fibers and diode laser have become the very important components in the light wave communication system. It is very important information “ how much power from a propagation light signal with any distribution can be coupled to a guided mode of a fiber.” The efficiency of coupling is given by the power overlap integral (POI). We simulated the coupling efficiency between optical fiber and strip-loaded waveguides constructed of GaAs / AlGaAs at wavelength near 0.85 . In order to optimize the coupling between waveguide and fiber, we adjust the parameters of strip-loaded, including the core index, the core thickness, the strip height, and the strip width. At the last we can get the cioupling loss fall to under —0.31 dB in the best case. Chapter 2 Theoretical Analysis of Optical Waveguides 3 2.1 Formulations 3 2.1.1 Full Vector Formulations 4 2.1.2 Semi-Vector Formulations 6 2.1.3 Scalar Formulation 6 2.2 The Finite Difference Method 7 2.2.1 Formulation 7 2.2.2 Boundary Conditions 8 2.2.3 Formulation of the Difference Equations 9 2.3 The ADI Scheme 12 Chapter3 Modes of the Waveguide and Fiber 18 3.1 Validation 18 3.2 The Coupler Structures 19 Chapter 4 Numerical Results 31 4.1 Implements 31 4.2 Optimizing the coupling efficiency 33 4.2.1 decreasingly the index of the core 33 4.2.2 Reduce the thickness of the film 36 4.2.3 Adjust the height of the strip 38 4.2.4 Variation the width of the strip 41 4.3 Summary 43 Chapter 5 Conclusion 44 Bibliography 45

碩士
國立中興大學
生物科技學研究所
102
Infectious bursal disease virus (IBDV) is an acute and highly contagious virus which is main cause of infectious bursal disease. It primarily occurrs in 3-6 weeks chickens and seriously affects the economy loss of poultry industry. Currently, inactivated and attenuated vaccines are two main strategies for chicken IBD prevention. In recent years, the safer and low-cost vaccines are produced by using plants as a platform. In this study, we constructed Bamboo mosaic virus (BaMV), Tobacco mosaic virus (TMV), Foxtail mosaic virus (FoMV), and Potato virus X (PVX) as plant viral vectors. The coat protein genes of viral vectors are replaced with IBDV VP2 gene and fused with His-tag in the C-terminal, to generate BaMVdC-VP2His, TMVdC-VP2His, FoMVdC-VP2His, and PVXdC-VP2His. To test the VP2 production, these four recombinant viruses were individually transfected into Nicotiana benthamiana leaves by agro-infiltration. The results showed that among four viral vectors, BaMV vector expressed the most high-level accumulation of VP2 protein. In order to stably express VP2 protein in plants, we generated BaMVdC-VP2His transgenic N. benthamiana plants by Agrobacterium- mediated transformation. Western blot analysis confirmed the VP2 protein could be expressed in homologous transgenic lines. The virus like particles (VLP) of VP2 approximately 20-30 nm in diameter were purified and observed by transmission electron microscopy. Taking into account the environmental safety and high expression of VP2His protein, different gene silencing suppressors replace BaMV TGB or co-expression with BaMVdC-VP2His. Furthermore, complementation coat protein function of BaMVdC-VP2His by co-expression of BaMV CP. The results indicate VP2 protein dose not significantly increase. To develop edible vaccine, the transgenic barley (Hordeum vulgare) were generated. The results showed that BaMVdC-VP2His transgenic barley accumulated low VP2 protein. However, we have successfully established tissue culture and plant regeneration system in barley. We will use VP2-VLP to immuning chicken and to test the neutralizing antibodies production. We hope in the future, to develop subunit vaccine against IBDV by the BaMV based vector system.

博士
國立中央大學
物理學系
102
High quality polycrystalline samples of Mn3-xCoxTeO6 (x = 0, 1, 2) perovskite were synthesized using the solid-state reaction technique, that a portion of the Mn2+ ions are substituted by the Co2+ ions for samples x = 1, 2. The temperature dependence of X-ray and high resolution neutron diffraction were performed to check the nuclear phase transition and to detect the long-range antiferromagnetic ordering of the samples x = 1, 2. From the results of General Structure Analysis System (GSAS) refinement, the substitution of Co2+ for Mn2+ in Mn3TeO6 will not alters the symmetry of crystal structure (hexagonal, ), even the temperature was cooled down to 3 K. Order parameters analysis of neutron diffraction and χ-T measurement show that the transition temperature of antiferromagnetic order are changed from 35 to 40 K for x = 1 to 2, and relocations of Mn/Co ions are observed below 35 and 40 K for Mn2CoTeO6 and MnCo2TeO6, respectively. The thermal variation of lattice constants of Mn3TeO6 can be described by T4 phonon term, but that of Mn2CoTeO6 and of MnCo2TeO6 can be described by T2 conduction electron term. From magnetization and susceptibility measurements, another magnetic transition is revealed for Mn2CoTeO6 and for MnCo2TeO6 at the temperature ~ 185 K due to the order of moments of Co2+, and the magnetic domains in the system are changed with the increasing of applied magnetic fields. The incommensurate propagation vectors are shifted from k = [0, 0, 0.481] to [0, 0, 0.515] as the concentration of Co2+ increased from x = 1 to 2, and it changes from k = [0, 0, 0.4302] in Mn3TeO6 to k = [0, 0, 0.515] in MnCo2TeO6, that a reduction of k with increased concentration of Co is toward the commensurate propagation vector k = [0, 0, 0.5]. The unique Mn/Co spin is split into two magnetically different orbits through the refinement of magnetic structure.

This thesis details the measurement of the pp¯ → W gamma + X → munugamma + X cross section at s = 1.96 TeV using the DO detector at Fermilab, in 134.5 pb -1 of integrated luminosity. From the photon E T spectrum limits on anomalous couplings of the photon to the W are obtained. At 95% confidence level, limits of -1.05 < Deltakappa < 1.04 for lambda = 0 and -0.28 <lambda < 0.27 for Deltakappa = 0 are obtained on the anomalous coupling parameters. The charge signed rapidity difference from the data is displayed, and its significance discussed.

Atomic nuclei form an excellent playground to investigate the primary building blocks of nature in the context of fundamental interactions between particles. Long-range electroma- gnetic Coulomb interaction, short-range strong interaction which binds nucleons into atomic nuclei (nucleon-nucleon interaction), and weak interaction responsible for beta decay pose a serious challenge in theoretical description of the nuclear chart where a deep understanding of all of them is a must. The eld of study is highly interdisciplinary as the understanding of fundamental interactions have been the main goal of the Standard Model of particle physics - the theory which pretends to account for the fundamental laws of nature. Binary structure of atomic nucleus - the quantum system composed of two types of par- ticles protons and neutrons causes the asymmetry of the nucleon-nucleon interaction due to, for instance, electromagnetic interaction which acts only between protons. The analysis of bre- aking of the isospin symmetry in the so-called superallowed Fermi beta decay provides a unique opportunity to verify the basic assumption of the Standard Model, where hadronic structure is built upon three generations of quarks. For that reason one of the key point of the thesis was to focus on the research of unitarity of the Cabbibo-Kobayashi-Maskawa (CKM) quark mixing matrix (Nobel prize 2008 "for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature"). So far, the calculation of nuclear beta decay with an e ective nucleon-nucleon interaction does not contradict with this assumption. Therefore either, we live indeed in the three-generation-quark world or quarks of next generation are so massive that we need much more precise calculation to reach the required level of accuracy of the unitarity of CKM matrix. The Fermi beta decay is by no means the only channel of beta transition. With nearly the same probability the nucleus may decay in the Gamow-Teller channel where the spin change is involved. Many years ago it turned out that the transition probability is systematically overestimated by the theory with respect to experimental data. The observed reduction is re- sponsible for coining the term quenching for the reduction e ect related to the coupling constant of Gamow-Teller type of electroweak currents. The coupling constant has been studied within both nuclear and particle physics. The conclusion that has been made within this work allowed to reject the main hypothesis behind the quenching. Instead of suspecting the drawbacks of the theoretical approach itself it turned out that the solution of the puzzle of the quenching was most probably related to many-body currents, which had been not included at any point in the calculation. Only very recently this statement has been con rmed by the ab initio calculations in several examples of the Gamow-Teller beta decay. Furthermore, the Gamow-Teller transitions are crucial to settle up the research on neutri- noless double beta decay. It is one of the most sought-after process in physics as if measured, would indicate the existence of new physics beyond the Standard Model with neutrino being its own antiparticle with the non-zero mass. The discovery of the neutrino oscillation (Nobel prize 2015) made the subject even more vivid among scientists. It meant that neutrinos are massive. It is therefore obligatory for nuclear theory to perform extremely precise calculation indicating possible isotopes that may decay in that exciting neutrinoless double decay channel. The model that has been widely tested and explored within the thesis, especially in the context of Gamow-Teller transitions, is now almost ready for the calculation of the 0 channel.

The nature of interactions of fundamental particles is governed by symmetries. These interactions are well described by an elegant and simple SU(3)c x SU(2)L x U(1)Y symmetric gauge theory that we call the Standard Model (SM) of particle physics. Very recently the CMS and ATLAS experiments at the Large Hadron Collider (LHC) confirmed the discovery of a boson of mass of about 125 GeV. Already, the data collected from these experiments seem to indicate that this particle is in fact the last missing piece and essential ingredient of the Standard Model : the Higgs boson. The Higgs has the very distinct role of providing a mechanism through which masses for other particles can be generated without destroying gauge invariance and hence the renormalizability of the theory. While this discovery completes the picture we have of the SM, the SM itself does not account for several experimentally observed phenomena , notably, dark matter (DM) and the baryon asymmetry in the universe (BAU). From a theoretical perspective a possibility for gauge coupling unification, an explanation for the quark flavour structure and the stability of the Higgs mass to radiative corrections are features that are absent in the framework of SM. This provides a strong basis to the hypothesis that there must be some intermediate scale (between the Planck scale and electroweak scale) of new physics, i.e. physics beyond the SM (BSM). The renormalizability of SM guarantees that various parameters of SM can be determined from the electroweak scale all the way up to the Planck scale. It is interesting to note that the RG evolution of the Higgs quartic coupling is driven to smaller values and can also become negative as the energy scale increases. Naively, a negative quartic coupling indicates destabilization of the EWSB vacuum. The energy scale at which the quartic coupling becomes negative would signify a break down of the theory and would set a scale for new physics. In principle the potential can be made stable through Planck scale dynamics and other vacua (other than the EWSB vacuum) may crop up. In this scenario the EWSB vacuum may decay to the deeper vacua. It is safe to say that, within experimental uncertainties of the Higgs and top quark masses the EWSB vacuum appears to be metastable. We are now left clueless: neither do we have any hints as to the nature of BSM physics nor the scale at which SM breaks down and new physics is assured. One should also note that although the evidence for BSM is compelling, data analysed from 7 and 8 TeV runs of the LHC have not produced any signals of BSM physics so far. Thus any indications of TeV scale BSM physics have been eluding us. In such a scenario the Higgs boson has assumed the role of a portal to study the possibilities of new physics. This is also motivated by the key role that the Higgs plays in generation of mass in a gauge symmetric theory. It is therefore reasonable to assume that the Higgs boson does in fact couple to particles predicted in BSM physics. Such couplings would play a role in modifying the properties of this boson. It is now essential to determine the properties of the Higgs as precisely as possible to search for signs of BSM. This thesis explores the idea of using the Higgs as a portal to study BSM physics. The properties of the Higgs that have already been measured with data from the first two runs of the LHC are its mass, branching ratios, spin and CP. When placed in the framework of a particular new physics model, these properties impose restrictions on the couplings and masses of BSM particles. A strong candidate for a BSM scenario is a Supersymmetric extension of the SM. Supersymmetry is an extension of the Poincar´e group that describes space time symmetries. Fermionic and bosonic degrees of freedom are mixed through the generators of this extended symmetry. In the minimal supersymmetric extension of the SM (MSSM), each particle of SM has a corresponding superpartner with identical quantum numbers modulo its spin. Since we do not see, for example, a bosonic superpartner of the fermionic top quark of the same mass as that of the top quark, this must mean that the supersymmetry, even if it is realized in nature, is not exact and must be broken. Although the symmetry may be broken the MSSM has some very appealing features: stabilization of the Higgs mass to quantum corrections, gauge coupling unification and possible dark matter candidate if the lightest Supersymmetric particle happens to be both stable and neutral. It is interesting to note that in MSSM, the tree level Higgs mass is bounded from above by the Z boson mass ( ~90 GeV ). The measured value of the Higgs mass (~126 GeV ) is still achievable in the MSSM through quantum corrections, the largest contribution coming from the top quarks and stop squarks. One therefore sees that the mass of the Higgs can already provide information about top superpartners. The presence of additional charged and coloured scalars implies the possibility of existence of charge and colour breaking (CCB) minima which would affect the stability of the Electroweak Symmetry breaking (EWSB) minima generated by the Higgs potential. Stability of EWSB is then dependent on parameters in the scalar sector of MSSM. We explore the nexus between the Higgs mass and vacuum stability in this model and find restrictions on the MSSM parameter space. The lighter Higgs of the MSSM couples differently to SM particles than the SM Higgs boson. More specifically one expects the couplings of the MSSM Higgs to gauge bosons to be smaller than in SM and unlike the SM Higgs, up type quarks have couplings strengths that are different from that of down type quarks. In the decoupling regime these differences become negligible and the lighter MSSM Higgs behaves identically to the SM Higgs. The measured Higgs rates do not show any large deviations from the expectations of a SM Higgs. It is therefore reasonable to assume that MSSM, if realized, resides in the decoupling regime. While tree level processes are not altered significantly in this regime, the same cannot be said about loop induced processes such as (h→ γγ) or (gg → h). Such processes may be affected significantly by sparticles running in the loops. Higgs decays to two photons can be strongly affected by the stau sector of MSSM and we study this in connection with EWSB vacuum stability. In several models of dark matter, the dark matter candidate particle couples to the Higgs boson. It may well be that this candidate particle may be light enough so that the decay of the Higgs boson to these particles may be possible. For example, in the framework of the MSSM, the LSP (˜χ01) is the dark matter candidate and a decay of the form hχ˜→01χ˜01is possible depending on the mass and strength of coupling of such a particle. At the LHC this would show up as an branching ratio to particles that are invisible to the detectors. The dominant production mode of the Higgs at LHC proceeds through gluon fusion. In this channel a signal for an “invisibly” decaying Higgs would show up as missing energy plus jets at LHC. This has already been studied in quite some detail. We focus on other production modes, namely Vector Boson Fusion (VBF) and associated production (VH), in determining an invisible branching fraction at LHC. These two production channels are much less sensitive to any other BSM signals that may mimic an invisibly decaying Higgs and thus provide clean signals for the latter. A determination of the nature of interactions between the Higgs and gauge bosons is of paramount importance. An understanding of these interactions is closely tied to an understanding of the nature of EWSB. There are two aspects to probing these interactions. One is a determination of the Lorentz structure of the Higgs and gauge boson vertices and the second is to determine the strength of its couplings. The Higgs coupling to two gauge bosons (the hVV vertex) in SM is of the form ~ agµν . Under the assumption that BSM physics does not alter this Lorentz structure, information about possible new physics can be simply extracted through a determination of the strength of the coupling aV . However, the most general structure of this vertex is of the form (aV gµν + bV pµq ν + cV ɛ µνρσpρqσ) . Here p and q are the sum and difference of the two gauge boson momenta respectively and ɛµνρσ the completely antisymmetric Levi-Civita tensor. The term cV parametrizes CP-odd couplings while the rest are CP-even. The terms proportional to b V and cV may be generated by new physics. But which new physics model do we look at? There are a plethora of such models. Rather than shooting in the dark at random BSM directions one could adopt the following approach. In the absence of BSM signals at the LHC so far, one could assume that the scale of physics is relatively high and BSM particles are more massive than SM particles and can therefore be integrated out of the Lagrangian. It is also prudent to assume that new physics respects the SU(3)c x SU(2)L x U(1)Y gauge symmetry of SM. With these two assumptions in hand, one could supplement the SM Lagrangian with additional operators. These operators which generally have mass dimensions greater than four would destroy the renormalizability of the theory, though an interpretation as an effective theory up to a scale Λ is still valid. The idea is to now study the consequences that this effective theory would have on measurable properties of the Higgs. The effective theory could affect both the Lorentz structure as well as the strength of the couplings of the Higgs to the gauge bosons. This thesis deals with the determination of the Lorentz structure of the Higgs coupling to two gauge bosons , i.e the trilinear vertex. An analysis of this for the hZZ vertex has already been performed by ATLAS and CMS using h → ZZ *decays. A pure pseudoscalar Higgs (cZ ≠0, aZ = bZ = 0) coupling has been ruled out at about 2 ~ 3 σ level. Bounds have also been placed on a mixed scalar-pseudoscalar coupling (a Z =0,cZ =0,bZ = 0). This however, is not the end of the story. There are two important points to note here. Firstly it is important to be able to verify these findings in other production modes. To this end, we investigate the ability of VBF production to probe such anomalous couplings and find strong effects on the pseudo-rapidity distributions of the tagging jets in VBF. Secondly it is important to also look for such anomalous couplings in the hWW vertex. At this point, one might argue that the hZZ vertex and hWW vertex are connected by Custodial symmetry. However this symmetry is violated in SM by gauging of the hypercharge. It follows that violations of this symmetry should arise naturally in BSM physics. A study of the anomalous vertex is not easily achieved in h→ WW ∗ decays due to backgrounds and difficulties in reconstructing momenta. The VBF channel can be quite effective here although there is significant contamination from VBF production through the Z boson. We find that a cleaner production mode to use would be associated production. Until recently the low cross-section of Vh made it difficult to analyse this channel at LHC. An analysis of Vh has been made possible by the use of modern jet substructure techniques using (h→ bb) decays. We use these techniques and study how one can probe anomalous couplings in the Vh production mode at LHC. One of the most important couplings of the Higgs is that to the top, the heaviest SM particle. Not only is this coupling responsible for the main production channel of the SM Higgs at the LHC but the interaction with the top also has important consequences on spontaneous symmetry breaking within the SM – notably, vacuum stability arguments – as well as beyond the SM – supersymmetry, for instance, where the top drives electroweak symmetry breaking in some scenarios. The strength as well as the CP property of the Higgs top coupling is therefore an important aspect of to study. more specifically we investigate terms of the form ψ¯t(at + ibtγ5)ψth. here ψt and h corresponds to the top quark and Higgs fields respectively. at and bt parametrize scalar and pseudoscalar couplings respectively. Since the dominant production mode of the Higgs at the LHC (gluon fusion) proceeds through a top quark loop as do decays of the Higgs to two photons, some information about these couplings may be extracted just by looking at Higgs production and decay rates. However, an unambiguous determination of these couplings is possible only through Higgs production with a top and anti-top pair. Although the production rates are very small at the LHC, such a study is of prime importance. We investigate t¯th production at the LHC and list some useful observable that can probe the couplings described above. The outline of the thesis is as follows. We start with brief introduction to SM and Electroweak Symmetry breaking (EWSB) also briefly reviewing SM Higgs production and decay at the LHC. We then investigate the information that the Higgs mass in conjunction with stability of the EWSB vacuum provides about the stop sector of the MSSM. We further investigate the information that Higgs decay rates in conjunction with the stability of the EWSB vacuum could provide about the stau sector in the MSSM. We move on to examining the extent to which an invisible branching ratio of the Higgs could be measured or excluded directly at the LHC. Coming to the second part of the thesis we examine in a model independent way the nature of the Higgs-gauge boson couplings. We first give a brief description of the Higgs gauge boson vertex and the effective theory approach following it up with a description of how this could be probed using Higgs decays. We then follow it up with a study on how the Lorentz structure could affect Higgs production in Vector Boson fusion and Higgs production in association with W or Z boson. Finally, we show how the CP properties of the Higgs coupling to the top quark can be investigated using tth production along with Higgs rates.

The nature of interactions of fundamental particles is governed by symmetries. These interactions are well described by an elegant and simple SU(3)c x SU(2)L x U(1)Y symmetric gauge theory that we call the Standard Model (SM) of particle physics. Very recently the CMS and ATLAS experiments at the Large Hadron Collider (LHC) confirmed the discovery of a boson of mass of about 125 GeV. Already, the data collected from these experiments seem to indicate that this particle is in fact the last missing piece and essential ingredient of the Standard Model : the Higgs boson. The Higgs has the very distinct role of providing a mechanism through which masses for other particles can be generated without destroying gauge invariance and hence the renormalizability of the theory. While this discovery completes the picture we have of the SM, the SM itself does not account for several experimentally observed phenomena , notably, dark matter (DM) and the baryon asymmetry in the universe (BAU). From a theoretical perspective a possibility for gauge coupling unification, an explanation for the quark flavour structure and the stability of the Higgs mass to radiative corrections are features that are absent in the framework of SM. This provides a strong basis to the hypothesis that there must be some intermediate scale (between the Planck scale and electroweak scale) of new physics, i.e. physics beyond the SM (BSM). The renormalizability of SM guarantees that various parameters of SM can be determined from the electroweak scale all the way up to the Planck scale. It is interesting to note that the RG evolution of the Higgs quartic coupling is driven to smaller values and can also become negative as the energy scale increases. Naively, a negative quartic coupling indicates destabilization of the EWSB vacuum. The energy scale at which the quartic coupling becomes negative would signify a break down of the theory and would set a scale for new physics. In principle the potential can be made stable through Planck scale dynamics and other vacua (other than the EWSB vacuum) may crop up. In this scenario the EWSB vacuum may decay to the deeper vacua. It is safe to say that, within experimental uncertainties of the Higgs and top quark masses the EWSB vacuum appears to be metastable. We are now left clueless: neither do we have any hints as to the nature of BSM physics nor the scale at which SM breaks down and new physics is assured. One should also note that although the evidence for BSM is compelling, data analysed from 7 and 8 TeV runs of the LHC have not produced any signals of BSM physics so far. Thus any indications of TeV scale BSM physics have been eluding us. In such a scenario the Higgs boson has assumed the role of a portal to study the possibilities of new physics. This is also motivated by the key role that the Higgs plays in generation of mass in a gauge symmetric theory. It is therefore reasonable to assume that the Higgs boson does in fact couple to particles predicted in BSM physics. Such couplings would play a role in modifying the properties of this boson. It is now essential to determine the properties of the Higgs as precisely as possible to search for signs of BSM. This thesis explores the idea of using the Higgs as a portal to study BSM physics. The properties of the Higgs that have already been measured with data from the first two runs of the LHC are its mass, branching ratios, spin and CP. When placed in the framework of a particular new physics model, these properties impose restrictions on the couplings and masses of BSM particles. A strong candidate for a BSM scenario is a Supersymmetric extension of the SM. Supersymmetry is an extension of the Poincar´e group that describes space time symmetries. Fermionic and bosonic degrees of freedom are mixed through the generators of this extended symmetry. In the minimal supersymmetric extension of the SM (MSSM), each particle of SM has a corresponding superpartner with identical quantum numbers modulo its spin. Since we do not see, for example, a bosonic superpartner of the fermionic top quark of the same mass as that of the top quark, this must mean that the supersymmetry, even if it is realized in nature, is not exact and must be broken. Although the symmetry may be broken the MSSM has some very appealing features: stabilization of the Higgs mass to quantum corrections, gauge coupling unification and possible dark matter candidate if the lightest Supersymmetric particle happens to be both stable and neutral. It is interesting to note that in MSSM, the tree level Higgs mass is bounded from above by the Z boson mass ( ~90 GeV ). The measured value of the Higgs mass (~126 GeV ) is still achievable in the MSSM through quantum corrections, the largest contribution coming from the top quarks and stop squarks. One therefore sees that the mass of the Higgs can already provide information about top superpartners. The presence of additional charged and coloured scalars implies the possibility of existence of charge and colour breaking (CCB) minima which would affect the stability of the Electroweak Symmetry breaking (EWSB) minima generated by the Higgs potential. Stability of EWSB is then dependent on parameters in the scalar sector of MSSM. We explore the nexus between the Higgs mass and vacuum stability in this model and find restrictions on the MSSM parameter space. The lighter Higgs of the MSSM couples differently to SM particles than the SM Higgs boson. More specifically one expects the couplings of the MSSM Higgs to gauge bosons to be smaller than in SM and unlike the SM Higgs, up type quarks have couplings strengths that are different from that of down type quarks. In the decoupling regime these differences become negligible and the lighter MSSM Higgs behaves identically to the SM Higgs. The measured Higgs rates do not show any large deviations from the expectations of a SM Higgs. It is therefore reasonable to assume that MSSM, if realized, resides in the decoupling regime. While tree level processes are not altered significantly in this regime, the same cannot be said about loop induced processes such as (h→ γγ) or (gg → h). Such processes may be affected significantly by sparticles running in the loops. Higgs decays to two photons can be strongly affected by the stau sector of MSSM and we study this in connection with EWSB vacuum stability. In several models of dark matter, the dark matter candidate particle couples to the Higgs boson. It may well be that this candidate particle may be light enough so that the decay of the Higgs boson to these particles may be possible. For example, in the framework of the MSSM, the LSP (˜χ01) is the dark matter candidate and a decay of the form hχ˜→01χ˜01is possible depending on the mass and strength of coupling of such a particle. At the LHC this would show up as an branching ratio to particles that are invisible to the detectors. The dominant production mode of the Higgs at LHC proceeds through gluon fusion. In this channel a signal for an “invisibly” decaying Higgs would show up as missing energy plus jets at LHC. This has already been studied in quite some detail. We focus on other production modes, namely Vector Boson Fusion (VBF) and associated production (VH), in determining an invisible branching fraction at LHC. These two production channels are much less sensitive to any other BSM signals that may mimic an invisibly decaying Higgs and thus provide clean signals for the latter. A determination of the nature of interactions between the Higgs and gauge bosons is of paramount importance. An understanding of these interactions is closely tied to an understanding of the nature of EWSB. There are two aspects to probing these interactions. One is a determination of the Lorentz structure of the Higgs and gauge boson vertices and the second is to determine the strength of its couplings. The Higgs coupling to two gauge bosons (the hVV vertex) in SM is of the form ~ agµν . Under the assumption that BSM physics does not alter this Lorentz structure, information about possible new physics can be simply extracted through a determination of the strength of the coupling aV . However, the most general structure of this vertex is of the form (aV gµν + bV pµq ν + cV ɛ µνρσpρqσ) . Here p and q are the sum and difference of the two gauge boson momenta respectively and ɛµνρσ the completely antisymmetric Levi-Civita tensor. The term cV parametrizes CP-odd couplings while the rest are CP-even. The terms proportional to b V and cV may be generated by new physics. But which new physics model do we look at? There are a plethora of such models. Rather than shooting in the dark at random BSM directions one could adopt the following approach. In the absence of BSM signals at the LHC so far, one could assume that the scale of physics is relatively high and BSM particles are more massive than SM particles and can therefore be integrated out of the Lagrangian. It is also prudent to assume that new physics respects the SU(3)c x SU(2)L x U(1)Y gauge symmetry of SM. With these two assumptions in hand, one could supplement the SM Lagrangian with additional operators. These operators which generally have mass dimensions greater than four would destroy the renormalizability of the theory, though an interpretation as an effective theory up to a scale Λ is still valid. The idea is to now study the consequences that this effective theory would have on measurable properties of the Higgs. The effective theory could affect both the Lorentz structure as well as the strength of the couplings of the Higgs to the gauge bosons. This thesis deals with the determination of the Lorentz structure of the Higgs coupling to two gauge bosons , i.e the trilinear vertex. An analysis of this for the hZZ vertex has already been performed by ATLAS and CMS using h → ZZ *decays. A pure pseudoscalar Higgs (cZ ≠0, aZ = bZ = 0) coupling has been ruled out at about 2 ~ 3 σ level. Bounds have also been placed on a mixed scalar-pseudoscalar coupling (a Z =0,cZ =0,bZ = 0). This however, is not the end of the story. There are two important points to note here. Firstly it is important to be able to verify these findings in other production modes. To this end, we investigate the ability of VBF production to probe such anomalous couplings and find strong effects on the pseudo-rapidity distributions of the tagging jets in VBF. Secondly it is important to also look for such anomalous couplings in the hWW vertex. At this point, one might argue that the hZZ vertex and hWW vertex are connected by Custodial symmetry. However this symmetry is violated in SM by gauging of the hypercharge. It follows that violations of this symmetry should arise naturally in BSM physics. A study of the anomalous vertex is not easily achieved in h→ WW ∗ decays due to backgrounds and difficulties in reconstructing momenta. The VBF channel can be quite effective here although there is significant contamination from VBF production through the Z boson. We find that a cleaner production mode to use would be associated production. Until recently the low cross-section of Vh made it difficult to analyse this channel at LHC. An analysis of Vh has been made possible by the use of modern jet substructure techniques using (h→ bb) decays. We use these techniques and study how one can probe anomalous couplings in the Vh production mode at LHC. One of the most important couplings of the Higgs is that to the top, the heaviest SM particle. Not only is this coupling responsible for the main production channel of the SM Higgs at the LHC but the interaction with the top also has important consequences on spontaneous symmetry breaking within the SM – notably, vacuum stability arguments – as well as beyond the SM – supersymmetry, for instance, where the top drives electroweak symmetry breaking in some scenarios. The strength as well as the CP property of the Higgs top coupling is therefore an important aspect of to study. more specifically we investigate terms of the form ψ¯t(at + ibtγ5)ψth. here ψt and h corresponds to the top quark and Higgs fields respectively. at and bt parametrize scalar and pseudoscalar couplings respectively. Since the dominant production mode of the Higgs at the LHC (gluon fusion) proceeds through a top quark loop as do decays of the Higgs to two photons, some information about these couplings may be extracted just by looking at Higgs production and decay rates. However, an unambiguous determination of these couplings is possible only through Higgs production with a top and anti-top pair. Although the production rates are very small at the LHC, such a study is of prime importance. We investigate t¯th production at the LHC and list some useful observable that can probe the couplings described above. The outline of the thesis is as follows. We start with brief introduction to SM and Electroweak Symmetry breaking (EWSB) also briefly reviewing SM Higgs production and decay at the LHC. We then investigate the information that the Higgs mass in conjunction with stability of the EWSB vacuum provides about the stop sector of the MSSM. We further investigate the information that Higgs decay rates in conjunction with the stability of the EWSB vacuum could provide about the stau sector in the MSSM. We move on to examining the extent to which an invisible branching ratio of the Higgs could be measured or excluded directly at the LHC. Coming to the second part of the thesis we examine in a model independent way the nature of the Higgs-gauge boson couplings. We first give a brief description of the Higgs gauge boson vertex and the effective theory approach following it up with a description of how this could be probed using Higgs decays. We then follow it up with a study on how the Lorentz structure could affect Higgs production in Vector Boson fusion and Higgs production in association with W or Z boson. Finally, we show how the CP properties of the Higgs coupling to the top quark can be investigated using tth production along with Higgs rates.