Download or read book Massive Gravity on a Brane written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Theoretical and Observational Consistency of Massive Gravity written by Lavinia Heisenberg and published by Springer. This book was released on 2015-06-12 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Brane localized Gravity written by Philip D. Mannheim and published by World Scientific. This book was released on 2005 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Basic Concepts of String Theory written by Ralph Blumenhagen and published by Springer Science & Business Media. This book was released on 2012-10-03 with total page 787 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Beyond Einstein Gravity written by Jorge Ovalle and published by Springer Nature. This book was released on 2020-01-16 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Chern simons Super gravity written by Mokhtar Hassaine and published by World Scientific. This book was released on 2016-01-07 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: '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.
Download or read book Cosmology and Gravity in the Brane World written by James Blackman Dent and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Branes of Gravity written by H.C. Huang and published by Xlibris Corporation. This book was released on 2011-01-07 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Strings Branes and Gravity written by Shamit Kachru and published by World Scientific. This book was released on 2001 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Modifications of Einstein s Theory of Gravity at Large Distances written by Eleftherios Papantonopoulos and published by Springer. This book was released on 2014-11-04 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Foundations of Massive Gravity written by Andrew Matas and published by . This book was released on 2015 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: General Relativity (GR) is a relativistic theory of gravity which has a large number of theoretical and observational successes. From the perspective of quantum field theory, GR can be thought of as a theory of a massless spin-2 particle called the graviton. It is a fundamental question to ask how the graviton behaves if it has a small but non-zero mass. In this dissertation I shall study the recently constructed theory of ghost-free massive gravity, which avoids the pernicious Boulware-Deser ghost that had thwarted previous attempts to study massive gravity.In Chapter 1 I will give a broad overview of the context, motivation, and model-building issues underlying massive gravity. Then in Chapter 2 I will give a detailed pedagogical introduction to ghost-free massive gravity focusing on concepts that will be used throughout the remainder of the work.In Chapter 3 I will derive the ghost-free structure of massive gravity from an extra dimensional perspective through a process known as Dimensional Deconstruction. Before my work it had been an open question whether Deconstruction could be consistently applied to gravity. The key insight relies on using the elegant formulation of General Relativity in terms of the vielbein. Inspired by Deconstruction, in Chapter 4 I will discuss the possibility of non-standard kinetic interactions in massive gravity. I will show that the only consistent derivative interactions for a massive spin-2 particle must be the same as in GR. This is remarkable because there is no known symmetry reason for this to be the case, since massive gravity breaks diffeomorphism invariance. Finally, in Chapter 5, in order to connect with observations I shall consider the radiation emitted from binary systems in Galileon theories, which are scalar theories that can mimic the behavior of a massive graviton. This work extends the understanding of the Vainshtein screening mechanism into a time-dependent situation.
Download or read book Brane localized Gravity written by Philip D. Mannheim and published by World Scientific. This book was released on 2005 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Massive Gravity in Curved Spacetimes and Other Related Topics written by Laura A. Johnson and published by . This book was released on 2020 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many aspects of gravity remain to be fully understood and many open questions remain. One of the long-standing puzzles is the cosmological constant problem and the nature of dark energy. Doing a standard back of the envelope quantum mechanics calculation, one would expect the size of the cosmological constant to be very large. Yet instead, we find a strangely small, but non-zero value. Massive gravity, a small deformation to the theory of general relativity giving the graviton a mass proposes new solutions to understanding this problem. In addition to its potential relevance to cosmology, massive gravity has many interesting theoretical aspects such as shift symmetries that fix the non-linear structure of its massless decoupling limit interactions, and 4-pt amplitudes that are a double copy of massive Yang--Mills. This thesis probes these aspects of massive gravity. In addition to massive gravity, it explores aspects of scalar theories with shift symmetries that give rise to enhanced soft limits and how they behave like gauge theories and gravity, and it also investigates interactions of pseudo-linear spin-2 fields, which can evade no-go results that rely on additional assumptions not satisfied by these types of interactions.
Download or read book The Scalar Tensor Theory of Gravitation written by Yasunori Fujii and published by Cambridge University Press. This book was released on 2003-01-02 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: A pedagogical overview of the theoretical ideas behind the cosmological constant problem, in particular the scalar-tensor theory, which is one of the most popular alternative theories of gravitation. Covering many developments in the field, including branes and quintessence, it will be an invaluable resource for graduate students and researchers alike.
Download or read book Gravity in Extra Dimensions of Infinite Volume written by and published by . This book was released on 2005 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we discuss various aspects of the Dvali-Gabadadze-Porrati (DGP) model in D-dimensions. Firstly, we generalize the DGP model, which consists of a delta-function type 3-brane embedded in an infinite volume bulk-space by allowing the 3-brane to have a finite thickness. We calculate the graviton propagator in the harmonic gauge both inside and outside the brane and discuss its dependence on the thickness of the brane. We obtain two infinite towers of massive modes and tachyonic ghosts. In the thin-brane limit, we recover the four-dimensional Einstein gravity behavior of the graviton propagator which was found in the delta-function treatment. We then examine the 4D worldvolume momentum dependence of the tensor structure. Secondly, we address the van Dam-Veltman-Zakharov (vDVZ) discontinuity of the 5D DGP model which arises from the breakdown of the perturbative expansion at linear order. Following a suggestion by Gabadadze [hep-th/0403161], we implement a constrained perturbative expansion parametrized by brane gauge-like parameters. We obtain the solution for the metric perturbations, explore the parameter space and show that the DGP solution exhibiting the vDVZ discontinuity corresponds to a set of measure zero. Thirdly, we discuss the weak-field Schwarzschild solution in the DGP model. By keeping up to second-order off-diagonal terms of the metric ansatz, we arrive at a perturbative expansion which is valid both far from and near the Schwarzschild radius. We calculate the lowest-order contribution explicitly and obtain the form of the metric both on the brane and in the bulk. As we approach the Schwarzschild radius, the perturbative expansion yields the standard four-dimensional Schwarzschild solution on the brane which is non-singular in the decoupling limit. This non-singular behavior is similar to the Vainshtein solution in massive gravity demonstrating the absence of the vDVZ discontinuity of the DGP model.
Download or read book Investigations in Three dimensional Topologically Massive Gravity written by Ilkka Oiva Vuorio and published by . This book was released on 1987 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gauge Gravity Duality written by Martin Ammon and published by Cambridge University Press. This book was released on 2015-04-09 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first textbook on this important topic, for graduate students and researchers in particle and condensed matter physics.
