[PDF] Massive Gravity On A Brane eBook

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File Size : 40,94 MB
Release : 2003
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At present no theory of a massive graviton is known that is consistent with experiments at both long and short distances. The problem is that consistency with long distance experiments requires the graviton mass to be very small. Such a small graviton mass however implies an ultraviolet cutoff for the theory at length scales far larger than the millimeter scale at which gravity has already been measured. In this paper we attempt to construct a model which avoids this problem. We consider a brane world setup in warped AdS spacetime and we investigate the consequences of writing a mass term for the graviton on a the infrared brane where the local cutoff is of order a large (galactic) distance scale. The advantage of this setup is that the low cutoff for physics on the infrared brane does not significantly affect the predictivity of the theory for observers localized on the ultraviolet brane. For such observers the predictions of this theory agree with general relativity at distances smaller than the infrared scale but go over to those of a theory of massive gravity at longer distances. A careful analysis of the graviton two-point function, however, reveals the presence of a ghost in the low energy spectrum. A mode decomposition of the higher dimensional theory reveals that the ghost corresponds to the radion field. We also investigate the theory with a brane localized mass for the graviton on the ultraviolet brane, and show that the physics of this case is similar to that of a conventional four dimensional theory with a massive graviton, but with one important difference: when the infrared brane decouples and the would-be massive graviton gets heavier than the regular Kaluza-Klein modes, it becomes unstable and it has a finite width to decay off the brane into the continuum of Kaluza-Klein states.

Author : Lavinia Heisenberg
Publisher : Springer
Page : 212 pages
File Size : 13,82 MB
Release : 2015-06-12
Category : Science
ISBN : 3319189352

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This work is a detailed study of both the theoretical and phenomenological consequences of a massive graviton, within the ghost-free theory of massive gravity, the de Rham-Gabadadze-Tolley (dRGT) theory. Its aim is to test the physical viability of the theory. It begins by putting constraints on the parameters of the theory in the decoupling limit based on purely theoretical grounds, like classical stability in the cosmological evolution of self-accelerating and degravitating solutions. The author then constructs a proxy theory to massive gravity from the decoupling limit resulting in non-minimally coupled scalar-tensor interactions as an example of a subclass of Horndeski theories. Lastly, she addresses the natural question of whether the parameters introduced in the dRGT theory are subject to strong renormalization by quantum loops and shows how the non-renormalization theorem protects the graviton mass from quantum corrections. Beyond the decoupling limit the quantum corrections are found to be proportional to the graviton mass, proving its technical naturalness.

Author : Philip D. Mannheim
Publisher : World Scientific
Page : 354 pages
File Size : 43,82 MB
Release : 2005
Category : Science
ISBN : 9812703136

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This timely and valuable book provides a detailed pedagogical introduction and treatment of the brane-localized gravity program of Randall and Sundrum, in which gravitational signals are able to localize around our four-dimensional world in the event that it is a brane embedded in an infinitely-sized, higher dimensional anti-de Sitter bulk space. A completely self-contained development of the material needed for brane-world studies is provided for both students and workers in the field, with a significant amount of the material being previously unpublished. Particular attention is given to issues not ordinarily treated in the brane-world literature, such as the completeness of tensor gravitational fluctuation modes, the causality of brane-world propagators, and the status of the massless graviton fluctuation mode in brane worlds in which it is not normalizable.

Author : Ralph Blumenhagen
Publisher : Springer Science & Business Media
Page : 787 pages
File Size : 50,15 MB
Release : 2012-10-03
Category : Science
ISBN : 3642294979

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The purpose of this book is to thoroughly prepare the reader for research in string theory at an intermediate level. As such it is not a compendium of results but intended as textbook in the sense that most of the material is organized in a pedagogical and self-contained fashion. Beyond the basics, a number of more advanced topics are introduced, such as conformal field theory, superstrings and string dualities - the text does not cover applications to black hole physics and cosmology, nor strings theory at finite temperatures. End-of-chapter references have been added to guide the reader wishing to pursue further studies or to start research in well-defined topics covered by this book.

Author : Jorge Ovalle
Publisher : Springer Nature
Page : 120 pages
File Size : 36,72 MB
Release : 2020-01-16
Category : Science
ISBN : 303039493X

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This book serves two main purposes: firstly, it shows, in a simple way, how the possible existence of an extra-spatial dimension would affect the predictions of four-dimensional General Relativity, a model known as the Brane world; secondly, it explains, step-by-step, a new technique called Minimal Geometric Deformation, which was introduced for the purpose of solving the correspondingly modified Einstein field equations. This method gave rise to the Gravitational Decoupling in General Relativity, which is widely used to solve the Einstein field equations in various contexts.

Author : Mokhtar Hassaine
Publisher : World Scientific
Page : 149 pages
File Size : 34,57 MB
Release : 2016-01-07
Category : Science
ISBN : 9814730955

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'The authors provide an up-to-date, well-organised background and essential elements of supergravity notions as well as all relevant aspects of Chern-Simons forms in gravitation. The book is a self-contained, informative, and much-needed broad introduction into the latest quantum gravity concepts, with a main focus on Chern-Simons gravity and supersymmetry … The book represents a comprehensive and systematic pedagogical exposition on gravitational Chern-Simons (Super)gravity theories, their applications, together with a selection of related recent developments in the field.'Contemporary PhysicsThis book grew out of a set of lecture notes on gravitational Chern-Simons (CS) theories developed over the past decade for several schools and different audiences including graduate students and researchers.CS theories are gauge-invariant theories that can include gravity consistently. They are only defined in odd dimensions and represent a very special class of theories in the Lovelock family. Lovelock gravitation theories are the natural extensions of General Relativity for dimensions greater than four that yield second-order field equations for the metric. These theories also admit local supersymmetric extensions where supersymmetry is an off-shell symmetry of the action, as in a standard gauge theory.Apart from the arguments of mathematical elegance and beauty, the gravitational CS actions are exceptionally endowed with physical attributes that suggest the viability of a quantum interpretation. CS theories are gauge-invariant, scale-invariant and background independent; they have no dimensional coupling constants. All constants in the Lagrangian are fixed rational coefficients that cannot be adjusted without destroying gauge invariance. This exceptional status of CS systems makes them classically interesting to study, and quantum mechanically intriguing and promising.

Author : James Blackman Dent
Publisher :
Page : pages
File Size : 45,5 MB
Release : 2005
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The cosmology in the Hubble expansion era of the Horava-Witten M-theory compactified on a Calabi-Yau threefold is studied in the reduction to five-dimensions where the effects of the Calabi-Yau manifold are summarized by the volume modulus, and all perturbative potentials are included. Matter on the branes are treated as first order perturbations of the static vacuum solution, and all equations in the bulk and all boundary conditions on both end branes are imposed. It is found that for a static volume modulus and a static fifth dimension, y, one can recover the four dimensional Robertson-Friedmann-Walker cosmology for relativistic matter on the branes, but not for non-relativistic matter. For relativistic matter, the Hubble parameter H becomes independent of y to first order in matter density, and if a consistent solution for nonrelativistic matter exists it would require H to be y dependent. These results hold also when an arbitrary number of 5-branes are included in the bulk. The five dimensional Horava-Witten model is compared with the Randall Sundrum phenomenology with a scalar field in the bulk where a bulk and brane potential are used so that the vacuum solutions can be rigorously obtained. (In the Appendix, the difficulty of obtaining approximate vacuum solutions for other potentials is discussed.) In this case nonrelativistic matter is accommodated by allowing the distance between the branes to vary. It is suggested that non-perturbative potentials for the vacuum solution of Horava-Witten theory are needed to remove the inconsistency that non-relativistic matter creates. Also considered is the problem of gravitational forces between point particles on the branes in a Randall-Sundrum (R-S) two brane model with S1/Z2 symmetry. Matter is assumed to produce a perturbation to the R-S vacuum metric and all the 5D Einstein equations are solved to linearized order (for arbitrary matter on both branes). We show that while the gauge condition h[subscript i]5 = 0, i = 0, 1, 2, 3 can always be achieved without brane bending, the condition h55 = 0 leads to large brane bending. The static potential arising from the zero modes and the corrections due to the Kaluza-Klein (KK) modes are calculated. Gravitational forces on the Planck (y1 = 0) brane recover Newtonian physics with small KK corrections (in accord with other work). However, forces on the TeV (y2) brane due to particles on that brane are strongly distorted by large R-S exponentials, making the model in disagreement with experiment if theTeV brane is the physical brane.

Author : Shamit Kachru
Publisher : World Scientific
Page : 954 pages
File Size : 31,24 MB
Release : 2001
Category : Science
ISBN : 9810247745

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Many of the topics in this book are outgrowths of the spectacular new understanding of duality in string theory which emerged around 1995. They include the AdS/CFT correspondence and its relation to holography, the matrix theory formulation of M theory, the structure of black holes in string theory, the structure of D-branes and M-branes, and detailed development of dualities with N = 1 and N = 2 supersymmetry. In addition, there are lectures covering experimental and phenomenological aspects of the Standard Model and its extensions, and discussions on cosmology including both theoretical aspects and the exciting new experimental evidence for a non-zero cosmological constant.

Author : H.C. Huang
Publisher : Xlibris Corporation
Page : 103 pages
File Size : 14,64 MB
Release : 2011-01-07
Category : Science
ISBN : 1456805045

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Branes of Gravity: The Structure of Gravitational Force, a new title by H. C. Huang, builds on the author’s earlier volume, A Simple Unified Theory: From Magnetism to Gravity. The author disagrees with some of the current beliefs in theoretical physics. For example, it is commonly believed that a perpetual machine is impossible. But this author thinks that our entire universe, galaxies, solar systems, and atoms are all, in effect, perpetual machines, whose motion still energizes everything we can sense. Based on the synthesis of discoveries in this book and the previous volume—covering such topics as how gravity and inertia differ, the Moon-Earth relationship, and applications of the neutral charge field—Huang discusses their implications for re-evaluating the structure and future understanding of physical nature and phenomena of particle universes.

Author : Eleftherios Papantonopoulos
Publisher : Springer
Page : 435 pages
File Size : 18,57 MB
Release : 2014-11-04
Category : Science
ISBN : 331910070X

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In the last few years modified gravity theories have been proposed as extensions of Einstein's theory of gravity. Their main motivation is to explain the latest cosmological and astrophysical data on dark energy and dark matter. The study of general relativity at small scales has already produced important results (cf e.g. LNP 863 Quantum Gravity and Quantum Cosmology) while its study at large scales is challenging because recent and upcoming observational results will provide important information on the validity of these modified theories. In this volume, various aspects of modified gravity at large scales will be discussed: high-curvature gravity theories; general scalar-tensor theories; Galileon theories and their cosmological applications; F(R) gravity theories; massive, new massive and topologically massive gravity; Chern-Simons modifications of general relativity (including holographic variants) and higher-spin gravity theories, to name but a few of the most important recent developments. Edited and authored by leading researchers in the field and cast into the form of a multi-author textbook at postgraduate level, this volume will be of benefit to all postgraduate students and newcomers from neighboring disciplines wishing to find a comprehensive guide for their future research.