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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Unification and explanation in early Kaluza-Klein theories

Muntean, Ioan Lucian. January 2009 (has links)
Thesis (Ph. D.)--University of California, San Diego, 2009. / Title from first page of PDF file (viewed September 17, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 444-468).
12

Aspectos gerais da teoria de Kaluza-Klein e mecanismo de compactificação

Almeida, Rodrigo dos Santos January 2016 (has links)
ALMEIDA, R. dos S. Aspectos gerais da teoria de Kaluza-Klein e mecanismo de compactificação. 2016. 52 f. Dissertação (Mestrado em Física) – Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Pós-Graduação em Física (posgrad@fisica.ufc.br) on 2017-10-19T13:42:21Z No. of bitstreams: 1 2016_dis_rsalmeida.pdf: 485609 bytes, checksum: c99272206044d096f79b32437b4ec5d0 (MD5) / Approved for entry into archive by Giordana Silva (giordana.nascimento@gmail.com) on 2017-10-25T22:37:35Z (GMT) No. of bitstreams: 1 2016_dis_rsalmeida.pdf: 485609 bytes, checksum: c99272206044d096f79b32437b4ec5d0 (MD5) / Made available in DSpace on 2017-10-25T22:37:35Z (GMT). No. of bitstreams: 1 2016_dis_rsalmeida.pdf: 485609 bytes, checksum: c99272206044d096f79b32437b4ec5d0 (MD5) Previous issue date: 2017 / In this work we will explore the theory of Kaluza-Klein, that proposes to unify the electromagnetism with the gravitation in one classical approach through the addition of one extra dimension (space type), thus obtaining one composed variety by 4 spatial dimensions and 1 time dimension. We will see how to obtain Einstein’s equations in this model and ,thereby, explain their consequences and restrictions when we do one dimensional reduction in order to rescue the known equations in 4 dimensions. We will analyse the compaction of this extra dimension and we will use one mechanism of spontaneous compaction in the case where we will have more than one extra dimension in the theory, this mechanism is known as flux compaction. This mechanism of compaction is done through the introduction of a tensor totally antisymmetric in the Eistein’s equations in 5 dimensions. Finally, we will approach the Kaluza-Klein theory using the formalism of differential forms, showing that it is a powerful tool in this study once that its algebra allowed us to obtain the same results in less time. / Neste trabalho explora-se a teoria de Kaluza-Klein que propõe unificar o eletromagnetismo com a gravitação em uma abordagem clássica mediante a adição de uma dimensão extra tipo espaço, assim obtendo uma variedade composta por 4-dimensões espaciais e 1dimensão temporal. Será visto como obter as equações de Einstein neste modelo e assim explanar suas consequências e restrições quando é feita uma redução dimensional para resgatar as equações já conhecidas em 4-dimensões. Será analisado a compactificação dessa dimensão extra e será usando um mecanismo de compactificação espontânea para o caso onde teremos mais de uma dimensão extra na teoria, mecanismo este conhecido por compactificação de Fluxo. Esse mecanismo de compactificação se da por meio da introdução de um tensor totalmente antissimétrico nas equações de Einstein em 5-dimensões. Por ultimo foi abordado a teoria de Kaluza-Klein usando o formalismos de formas diferenciais, mostrando ser uma poderosa ferramenta para tal estudo uma vez que sua álgebra nos permitiu obter os mesmos resultados em um menor tempo.
13

On the nature of time in cosmological perspective : a comparative study of the weak and strong interaction chronometries via an analysis of high resolution ⁸⁷Rb-β-̄⁸⁷Sr, ²³⁵/²³⁸U-α-²⁰⁷/⁷⁰⁶Pb and ¹⁴²Sm-α-¹⁴³Nd isotopic age determinations of meteoritic, lunar and geological samples

Harper, Charles L. January 1988 (has links)
No description available.
14

The embedding of gauged N = 8 supergravity into 11 dimensions

Krüger, Olaf 16 December 2016 (has links)
Diese Doktorarbeit behandelt die bosonische Einbettung der geeichten N = 8 Supergravitation in elf Dimensionen. Die höher dimensionalen Felder müssen zuerst nichtlinear umdefiniert werden, sodass ihre supersymmetrischen Transformationen mit denen der vierdimensionalen Felder verglichen werden können. So wurden in der Literatur nichtlineare Beziehungen zwischen den neu definierten elfdimensionalen Feldern und den Feldern der N = 8 Supergravitation gefunden. Darauf basierend können nun direkte Ansätze gefunden werden, die eine vierdimensionale in eine elfdimensionale Lösung der Supergravitation einbetten. Die Arbeit präsentiert alle Ansätze für die skalaren internen Felder. Zuerst werden die schon bekannten Einbettungsformeln für die inverse Metrik, das Dreiform-Potential mit gemischter Indexstruktur sowie das Sechsform-Potential zusammengefasst. Danach werden neue Ansätze für die explizite interne Metrik, das vollständige Dreiform-Potential, den Warp Faktor, die Vierform Feldstärke sowie den Freund-Rubin Faktor gefunden. Die Einbettung der Vektorbosonen hängt dann nur von den skalaren Feldern ab. Der zweite Teil der Arbeit benutzt die gefundenen Einbettungsformeln, um gruppeninvariante Lösungen der elfdimensionalen Supergravitation zu finden. In solchen Fällen hängen die höherdimensionalen Felder ausschließlich von speziellen gruppeninvarianten Tensoren ab, die auf die jeweilige interne Geometrie angepasst sind. Als Beispiel wird zuerst die schon bekannte Einbettung der G2 invarianten Supergravitation zusammengefasst. Dann wird eine neue SO(3)×SO(3) invariante Löung der elfdimensionalen Supergravitation gefunden. Schließlich wird die Konsistenz der gefundenen Lösungen für eine maximal symmetrische Raumzeit überprüft. Die Ergebnisse können auf andere Kompaktifizierungen verallgemeinert werden, z.B. auf die nichtkompakten CSO(p,q,r) Eichungen oder auf die Reduzierung der Typ IIB Supergravitation zu fünf Dimensionen. / This thesis presents the complete embedding of the bosonic section of gauged N = 8 supergravity into 11 dimensions. The fields of 11-dimensional supergravity are reformulated in a non-linear way, such that their supersymmetry transformations can be compared to the four-dimensional ones. In this way, non-linear relations between the redefined higher-dimensional fields and the fields of N = 8 supergravity were already found in the literature. This is the basis for finding direct uplift Ansätze for the bosonic fields of 11-dimensional supergravity in terms of the four-dimensional ones. This work gives the scalar Ans¨atze for the internal fields. First, the well known uplift formulae for the inverse metric, the three-form potential with mixed index structure and the six-form potential are summarized. Secondly, new embedding formulae for the explicit internal metric, the full three-form potential and the warp factor are presented. Additionally, two subsequent non-linear Ansätze for the full internal four-form field strength and the Freund-Rubin term are found. Finally, the vector uplift can simply be found in terms of the obtained scalar fields. The second part of this thesis uses the obtained embedding formulae in order to construct group invariant solutions of 11-dimensional supergravity. In such cases, the higher-dimensional fields can be written solely in terms of certain group invariant tensors that are adapted to the particular geometry of the internal space. Two such examples are discussed in detail. The first one is the well-known uplift of G2 gauged supergravity. Furthermore, a new SO(3)×SO(3) invariant solution of 11-dimensional supergravity is found. In particular, the consistency of both solutions is explicitly checked for a maximally symmetric spacetime. The results may be generalized to other compactifications, e.g. the non-compact CSO(p, q, r) gaugings or the reduction from type IIB supergravity to five dimensions.
15

Symétrie électrofaible à la lumière du LHC / Electroweak symmetry breaking in the light of LHC

Kubik, Bogna 05 October 2012 (has links)
Les extensions du Modèle Standard (MS) des particules sont maintenant dans une époque de développement très actif. Les motivations de l'introduction des dimensions supplémentaires sont basées d'une part sur la théorie des cordes qui nécessitent l'existence de nouvelles dimensions pour être cohérent. D'un autre côté ces théories peuvent potentiellement expliquer le problème de hiérarchie, le nombre de générations de fermions ou la stabilité du proton. La caractéristique commune de ces modèles est qu'ils fournissent une nouvelle particule neutre interagissant faiblement –un candidat idéal de la matière noire. Sa stabilité est préservée par la parité KK qui interdit les désintégrations du LKP en particules du MS. La géométrie de l'espace sous-jacent détermine le spectre de particules du modèle donc la masse et le spin du candidat DM, qui à leur tour jouent un rôle clé dans les études phénoménologiques. Nous présentons un modèle à deux dimensions supplémentaires universelles compactifiées sur le plan projectif réel. Cette géométrie particulière permet la définition des fermions chiraux et la stabilité de la matière noire neutre candidat dérive naturellement des propriétés intrinsèques de l'espace sans ajouter de nouvelles symétries ad hoc. Nous présentons le spectre de deux premiers niveaux KK à une boucle. Le spectre au sein de chaque niveau KK est fortement dégénéré ce qui fournit des signatures très intéressantes du modèle. Nous étudions la phénoménologie de la matière noire dans notre modèle pour limiter l'espace des paramètres en comparant nos résultats avec les données de WMAP et les expériences de détection directe. En utilisant les bornes obtenues, nous nous concentrons sur la phénoménologie LHC de notre modèle / The extra-dimensional extensions of the Standard Model of particles are now in a very active epoch of development. The motivations of introducing extra dimensions are based on one hand on string theories that require the existence of new dimensions to be consistent. On the other hand such theories can potentially explain the hierarchy problem, number of fermion generations, proton stability and other enigmas of the Standard Model. The common feature of these models is that they provide a new neutral weakly interacting particle - perfect candidate to the Dark Matter. Its stability is preserved by the so-called KK parity which prohibits the decays of the LKP into SM particles. The geometry of the underlying space determines the particle spectrum of the model, thus the mass and the spin of the DM candidate, which in turn plays the key role in the phenomenological studies We present a model with two universal extra dimensions compactified on a real projective plane. This particular geometry is chosen because chiral fermions can be defined on such orbifold and the stability of the neutral dark matter candidate arise naturally from the intrinsic geometrical properties of the space without adding any new symmetries ad hoc. We present the particle spectrum at loop order up to the second level in Kaluza-Klein expansion. The particularity of the spectrum is that the mass splittings within each KK level are highly degenerated providing a very interesting potential signatures in the LHC. We study the dark matter phenomenology in our model and constrain the parameter space by comparing our results with WMAP data and direct detection experiments. Using the obtained bounds we focus on the collider phenomenology of our model
16

Cosmological and theoretical aspects of higher dimensions

Fairbairn, Malcolm January 2001 (has links)
No description available.
17

Constraints on the Kaluza-Klein Photon as a Dark Matter Candidate from the IceCube Collaboration Results

Colom i Bernadich, Miquel January 2019 (has links)
New constraints on the scattering cross sections of the Kaluza Klein photon as a darkmatter candidate, its annihilation rate in the Sun and the resulting muon flux on Earth are derived.For this purpose, data collected in the IceCube Neutrino Observatory during 532 days of exposurein the austral winters between 2011 and 2014 have been analyzed with Poisson confidence intervals (J. Conrad et al., 2003) and compared to the simulated prediction achieved with the WimpSimsoftware (J. Edsjö et al., 2003). The results do not allow for any detection claim, but they improveby one order of magnitude the constraints formerly presented in R. Abbasi et al. (2010). Despitethe recent results from LHC experiment which discard lower masses for the Kaluza Klein photon (N. Deutschmann et al., 2017), the new constraints are still relevant for masses above 1500 GeV.
18

Etude de la production resonante de graviton de Kaluza-Klein dans ses desintegrations en paires de muons dans le modele de Ramdall-Sundrum aupres de l'experience D0 au Tevatron

Lahrichi, Nadia 02 July 2004 (has links) (PDF)
Dans cette thèse nous avons posé les premières contraintes sur les paramètres du modèle de dimensions supplémentaires de Randall-Sundrum, à savoir k/M_Pl qui est proportionnel au couplage du graviton aux champs du modèle standard et M_G qui est la masse du premier état excité du graviton. L'analyse du signal Monte Carlo est basée sur le générateur PYTHIA. Cette étude a permis de mettre en évidence et de rectifier une erreur dans le générateur PYTHIA grâce à l'élaboration d'un générateur indépendant dédié à cette analyse. Le lot de données utilisées pour l'analyse correspond à la période de prise des données effectuée par la collaboration Dzero au Tevatron allant de novembre 2002 à juillet 2003, qui correspond à une luminosité totale de 107,8 pb-1. La recherche du graviton dans ses désintégrations en paires de muons a permis de mesurer dans un premier temps la section efficace de production du boson Z multiplié par le rapport d'embranchement du Z en deux muons.
19

A Search for Dark Matter in the Sun with AMANDA and IceCube

Engdegård, Olle January 2011 (has links)
A search for weakly interacting massive particles (WIMPs) annihilating in the Sun was performed with the IceCube and AMANDA neutrino telescopes, using data from 2008 corresponding to 149 days of livetime. Assuming that particles in the dark matter halo scatter and accumulate in the centre of the Sun, Majorana WIMPs may pair-wise annihilate and give rise to a neutrino signal detectable in an experiment at Earth. No excess of muon-neutrinos from the Sun was observed, and limits on the νμ-flux were set for masses between 50 GeV and 5 TeV considering WIMPs annihilating into b‾b and W+W-. Separate limits were also calculated for the case of the lightest Kaluza-Klein particle. The flux limits were converted to limits on the spin-dependent and spin-independent WIMP-proton cross sections, σSD and σSI. The search was combined using a joint likelihood method with AMANDA and IceCube data from 2001-2007, yielding the 90% CL upper limits Φμ < 103 km-2y-1 for a WIMP mass of 1000 GeV and σSD < 1.28×10-4 pb for 250 GeV, both for the W+W- spectrum. / IceCube
20

Kaluza-klein Monopole

Sakarya, Emre 01 September 2007 (has links) (PDF)
Kaluza-Klein theories generally in $(4+D)$ and more specifically in five dimensions are reviewed. The magnetic monopole solutions found in the Kaluza-Klein theories are generally reviewed and their generalizations to Anti-de Sitter spacetimes are discussed.

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