Heidelberg, University, Diss., 2004.

In this work we explore the collider prospects for the asymptotic safety scenario being realized as a quantum theory of gravity. Testing gravity at colliders becomes a real possibility in the case of extra dimensional models, or with additional physics leading to a fundamental scale of gravity significantly lower than the Planck mass. We present several approximations for the full non-perturbative renormalization group running, and show how these can be implemented at the level of the graviton wave-function renormalization. The issue of scale identi fication of the physical process with the renormalization group scale k is clarified and several different choices are compared. The various approximations are resolved and shown in most cases to generate scheme independent results. On the phenomenological side, we investigate two separate observables. First, at tree-level we present results on LHC di-muon production due to asymptotically safe gravitons. By including fixed point scaling Kaluza- Klein modes, the predicted signal is enhanced and simultaneously problems associated with the breakdown of perturbative unitarity are reduced. At the one-loop level, we outline our calculation for the contribution to electro-weak precision observables originating from asymptotically safe gravity. New bounds are derived which show different behaviour as a function of the number of extra dimensions compared with previous effective field theory results. Finally, we comment on possible further directions for exploring the frontier of collider physics and quantum gravity.

University, Diss., 2002--Bonn.

Orientador: José Geraldo Pereira / Banca: Ruben Aldrovandi / Banca: Victor de Oliveira Rivelles / Banca: José Abdalla Helaÿel-Neto / Banca: José Wadih Maluf / Resumo: Na primeira parte da tese é feito um estudo dos fundamentos do equivalente teleparalelo da Relatividade Geral. Usando o fato que esse modelo corresponde a uma teoria de gauge para o grupo das translações, obtemos primeiramente a corrente de gauge representando a densidade de energia-momento do campo gravitacional, a qual se verifica ser um tensor verdadeiro. Sua relação com a expressão de Moller para o pseudo-tensor energia-momento canônico é também obtida. Então, para que resulte completamente equivalente com a Relatividade Geral, uma nova expressão para a conexão de spin teleparalela é proposta. Na segunda parte da tese, adotando-se a estrutura de gauge do Teleparalelismo como paradigma, desenvolvemos a versão teleparalela da teoria de Kaluza-Klein não- Abeliana. Nessa teoria, apenas o espaço interno (fibra) adquire dimensões extras, sendo o espaço-tempo mantido sempre quadri-dimensional. O processo de unificação neste formalismo resulta bem mais simples e natural do que nos modelos de Kaluza- Klein ordinários / Abstract: In the first part of the thesis, a study on the foundations of the teleparallel equivalent of General Relativity is made. Using the fact that it corresponds to a gauge theory for the translation group, we obtain first the energy-momentum gauge current of the gravitational field, which is shown to be a true tensor. Its relation to the usual expression obtained by Mpller for the canonical energy-momentum pseudo-tensor is also obtained. Then, in order to be fully equivalent with General Relativity, a new expression for the teleparallel spin connection is proposed. In the second part of the thesis, by adopting the gauge construction of teleparallel gravity as paradigm, a teleparallel version of the non-Abelian Kaluza-Klein theory is developed. In this theory, only the internai (fiber) space acquires extra dimensions, spacetime being kept always four-dimensional. The uniíication in this approach results to be much simpler and more natural than in ordinary Kaluza-Klein models / Doutor

published_or_final_version / abstract / Physics / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Orientador: José Geraldo Pereira / Mestre

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By using the concept of isometry Killing vectors were introduced. Generalizing the Killing vectors Killing tensors of rank two were briefly introduced. Their metrical properties have been dealt.With this path Killing &ndash / Yano tensors were introduced as being some hidden space-time symmetries and also square roots of Killing tensors of rank two. Also physical importance of Killing &ndash / Yano tensors were briefly introduced. A calculation for 4D pp-wave metric is reviewed. Standart 5-D Kaluza- Klein theory is rewieved in an anholonomic base. 5- D Killing &ndash / Yano equations are written in this base. Simplified forms of these equations are given and the necessary conditions on the EM field tensor and the KY tensor are presented

In this work the search for the dark matter arising from a model of extra dimensions, otherwise known as Kaluza Klein WIMPs, on the data taken with the AMANDA neutrino telescope in the South Pole is presented. The limit on the dark matter from the Kaluza Klein Solar WIMPs analysis on the data taken from year 2001 to 2003 is derived.