Mirage Cosmology
A. Kehagias,Elias Kiritsis +1 more
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In this article, a brane universe moving in a curved higher dimensional bulk space is considered, where the motion induces a cosmological evolution on the universe brane that is indistiguishable from a similar one induced by matter density on the brane.Abstract:
A brane universe moving in a curved higher dimensional bulk space is considered The motion induces a cosmological evolution on the universe brane that is indistiguishable from a similar one induced by matter density on the brane The phenomenological implications of such an idea are discussed Various mirage energy densities are found, corresponding to dilute matter driving the cosmological expansion, many having superluminal properties $|w|>1$ or violating the positive energy condition It is shown that energy density due to the world-volume fields is nicely incorporated into the picture It is also pointed out that the initial singularity problem is naturally resolved in this contextread more
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Modified Gravity and Cosmology
TL;DR: A comprehensive survey of recent work on modified theories of gravity and their cosmological consequences can be found in this article, where the authors provide a reference tool for researchers and students in cosmology and gravitational physics, as well as a selfcontained, comprehensive and up-to-date introduction to the subject as a whole.
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Can the dark energy equation - of - state parameter w be less than -1?
TL;DR: In this article, the authors study the stability of dynamical models exhibiting a negative kinetic term and show that these models might be phenomenologically viable if thought of as effective field theories valid only up to a certain momentum cutoff.
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Brane-World Gravity
Roy Maartens,Kazuya Koyama +1 more
TL;DR: In this article, the authors discuss the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional braneworlds based on the Randall-Sundrum models.
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The fundamental constants and their variation: observational and theoretical status
Abstract: This article describes the various experimental bounds on the variation of the fundamental constants of nature. After a discussion of the role of fundamental constants, their definition and link with metrology, it reviews the various constraints on the variation of the fine-structure constant, the gravitational, weak- and strong-interaction couplings and the electron-to-proton mass ratio. The review aims (1) to provide the basics of each measurement, (2) to show as clearly as possible why it constrains a given constant, and (3) to point out the underlying hypotheses. Such an investigation is of importance in comparing the different results and in understanding the recent claims of the detection of a variation of the fine-structure constant and of the electron-to-proton mass ratio in quasar absorption spectra. The theoretical models leading to the prediction of such variation are also reviewed, including Kaluza-Klein theories, string theories, and other alternative theories. Cosmological implications of these results are also discussed. The links with the tests of general relativity are emphasized.
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f(T) teleparallel gravity and cosmology
Yi-Fu Cai,Salvatore Capozziello,Mariafelicia De Laurentis,Emmanuel N. Saridakis,Emmanuel N. Saridakis,Emmanuel N. Saridakis +5 more
TL;DR: In this paper, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description.