Cosmological Constant and Fundamental Length

Anderson, James L.; Finkelstein, David

doi:10.1119/1.1986321

Cited by 184 publications

(232 citation statements)

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“…One approach along these lines is unimodular gravity [174]; in this theory, the determinant of the metric is fixed to be −1. A starting point to understand unimodular gravity is to consider the traceless Einstein equations following Weinberg [34] R µν − 1 4 Rg µν = 1 M 2…”

Section: Modifications To Einstein's Equationsmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Modifications To Einstein's Equationsmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…Here, unlike in unimodular gravity [11][12][13][14][15][16][17][18], there are no hidden equations nor integration constants, and all the sources are automatically accounted for in (1.4). The counterterm Λ is a global dynamical field fixed by the field equations.…”

Section: Jhep09(2017)074mentioning

confidence: 99%

An étude on global vacuum energy sequester

D’Amico

Kaloper

Padilla

et al. 2017

J. High Energ. Phys.

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Recently two of the authors proposed a mechanism of vacuum energy sequester as a means of protecting the observable cosmological constant from quantum radiative corrections. The original proposal was based on using global Lagrange multipliers, but later a local formulation was provided. Subsequently other interesting claims of a different nonlocal approach to the cosmological constant problem were made, based again on global Lagrange multipliers. We examine some of these proposals and find their mutual relationship. We explain that the proposals which do not treat the cosmological constant counterterm as a dynamical variable require fine tunings to have acceptable solutions. Furthermore, the counterterm often needs to be retuned at every order in the loop expansion to cancel the radiative corrections to the cosmological constant, just like in standard GR. These observations are an important reminder of just how the proposal of vacuum energy sequester avoids such problems.

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“…The conformal metric f is the sole gravitational variable of unimodular relativity. We assume that the metric tensor field gµν found by measuring the proper times dτ 2 = gµν dx µ dx ν for a sufficiently fine network of intervals dx µ , also determines the measure field µ by the usual relation (2). Once the measure µ has been experimentally determined it establishes a class of admissible metrics obeying (2).…”

Section: Introduction To Unimodular Relativitymentioning

confidence: 99%

“…Originally we proposed unimodular relativity because there is indeed an experimental atomic standard of length near each point of space-time, not built into general relativity [2] . This suggests that the macroscopic structure of space-time is a smoothed description of an underlying atomic space-time microstructure, which seems necessary for other reasons.…”

Section: Introduction To Unimodular Relativitymentioning

confidence: 99%

“…Unimodular relativity is an alternative theory of gravity considered by Einstein in 1919 [1] without a Lagrangian and put into Lagrangian form by Anderson and Finkelstein [2]. The space-time of unimodular relativity is a measure manifold, a manifold provided by nature with a fixed absolute physical measure field µ(x) to be found by direct measurement, subject to no dynamical development.…”

Section: Introduction To Unimodular Relativitymentioning

confidence: 99%

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Unimodular relativity and cosmological constant

Finkelstein

Galiautdinov

Baugh

2001

Journal of Mathematical Physics

113

145

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Unimodular relativity is a theory of gravity and space-time with a fixed absolute space-time volume element, the modulus, which we suppose is proportional to the number of microscopic modules in that volume element. In general relativity an arbitrary fixed measure can be imposed as a gauge condition, while in unimodular relativity it is determined by the events in the volume. Since this seems to break general covariance, some have suggested that it permits a non-zero covariant divergence of the material stress-energy tensor and a variable cosmological "constant." In Lagrangian unimodular relativity, however, even with higher-derivatives of the gravitational field in the dynamics, the usual covariant continuity holds and the cosmological constant is still a constant of integration of the gravitational field equations.

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Cosmological Constant and Fundamental Length

Cited by 184 publications

References 0 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

An étude on global vacuum energy sequester

Unimodular relativity and cosmological constant

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