scholarly journals Quantum interference in external gravitational fields beyond General Relativity

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
Luca Buoninfante ◽  
Gaetano Lambiase ◽  
Luciano Petruzziello
Keyword(s):  
General Relativity ◽  
Quantum Interference ◽  
Relativistic Effects ◽  
Newtonian Potential ◽  
Alternative Theories Of Gravity ◽  
Gravitational Fields ◽  
Decoherence Rate ◽  
Relativistic Regime ◽  
Theories Of Gravity ◽  
To Come

AbstractIn this paper, we study the phenomenon of quantum interference in the presence of external gravitational fields described by alternative theories of gravity. We analyze both non-relativistic and relativistic effects induced by the underlying curved background on a superposed quantum system. In the non-relativistic regime, it is possible to come across a gravitational counterpart of the Bohm–Aharonov effect, which results in a phase shift proportional to the derivative of the modified Newtonian potential. On the other hand, beyond the Newtonian approximation, the relativistic nature of gravity plays a crucial rôle. Indeed, the existence of a gravitational time dilation between the two arms of the interferometer causes a loss of coherence that is in principle observable in quantum interference patterns. We work in the context of generalized quadratic theories of gravity to compare their physical predictions with the analogous outcomes in general relativity. In so doing, we show that the decoherence rate strongly depends on the gravitational model under investigation, which means that this approach turns out to be a promising test bench to probe and discriminate among all the extensions of Einstein’s theory in future experiments.

scholarly journals Testing the Vainshtein mechanism using stars and galaxies

2015 ◽  
Vol 24 (12) ◽  
pp. 1544021 ◽  
Author(s):  
Jeremy Sakstein ◽  
Kazuya Koyama
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Main Sequence ◽  
Alternative Theories Of Gravity ◽  
The Novel ◽  
Main Sequence Stars ◽  
Cosmic Expansion ◽  
Astrophysical Objects ◽  
Theories Of Gravity ◽  
Alternative Theories

The Vainshtein mechanism is of paramount importance in many alternative theories of gravity. It hides deviations from general relativity (GR) in the solar system while allowing them to drive the acceleration of the cosmic expansion. Recently, a class of theories have emerged where the mechanism is broken inside astrophysical objects. In this essay, we look for novel probes of these theories by deriving the modified properties of stars and galaxies. We show that main-sequence stars are colder, less luminous and more ephemeral than GR predicts. Furthermore, the circular velocities of objects orbiting inside galaxies are slower and the lensing of light is weaker. We discuss the prospects for testing these theories using the novel phenomena presented here in light of current astrophysical surveys.

scholarly journals Beyond Einstein’s General Relativity: Hybrid metric-Palatini gravity and curvature-matter couplings

2020 ◽  
Vol 29 (13) ◽  
pp. 2030008 ◽  
Author(s):  
Tiberiu Harko ◽  
Francisco S. N. Lobo
Keyword(s):  
General Relativity ◽  
Human Mind ◽  
Compact Objects ◽  
Cosmic Acceleration ◽  
Modified Theories Of Gravity ◽  
Late Time ◽  
Gravitational Fields ◽  
Matter Coupling ◽  
Theories Of Gravity ◽  
Einstein’S General Relativity

Einstein’s General Relativity (GR) is possibly one of the greatest intellectual achievements ever conceived by the human mind. In fact, over the last century, GR has proven to be an extremely successful theory, with a well established experimental footing, at least for weak gravitational fields. Its predictions range from the existence of black holes and gravitational radiation (now confirmed) to the cosmological models. Indeed, a central theme in modern Cosmology is the perplexing fact that the Universe is undergoing an accelerating expansion, which represents a new imbalance in the governing gravitational equations. The cause of the late-time cosmic acceleration remains an open and tantalizing question, and has forced theorists and experimentalists to question whether GR is the correct relativistic theory of gravitation. This has spurred much research in modified theories of gravity, where extensions of the Hilbert–Einstein action describe the gravitational field, in particular, [Formula: see text] gravity, where [Formula: see text] is the curvature scalar. In this review, we perform a detailed theoretical and phenomenological analysis of specific modified theories of gravity and investigate their astrophysical and cosmological applications. We present essentially two largely explored extensions of [Formula: see text] gravity, namely: (i) the hybrid metric-Palatini theory; (ii) and modified gravity with curvature-matter couplings. Relative to the former, it has been established that both metric and Palatini versions of [Formula: see text] gravity possess interesting features but also manifest severe drawbacks. A hybrid combination, containing elements from both of these formalisms, turns out to be very successful in accounting for the observed phenomenology and avoids some drawbacks of the original approaches. Relative to the curvature-matter coupling theories, these offer interesting extensions of [Formula: see text] gravity, where the explicit nonminimal couplings between an arbitrary function of the scalar curvature [Formula: see text] and the Lagrangian density of matter, induces a nonvanishing covariant derivative of the energy-momentum tensor, which implies nongeodesic motion and consequently leads to the appearance of an extra force. We extensively explore both theories in a plethora of applications, namely, the weak-field limit, galactic and extragalactic dynamics, cosmology, stellar-type compact objects, irreversible matter creation processes and the quantum cosmology of a specific curvature-matter coupling theory.

scholarly journals ON GENERATING SOME KNOWN BLACK HOLE SOLUTIONS

2010 ◽  
Vol 25 (10) ◽  
pp. 835-842 ◽  
Author(s):  
F. RAHAMAN ◽  
MUBASHER JAMIL ◽  
A. GHOSH ◽  
K. CHAKRABORTY
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Alternative Theories Of Gravity ◽  
Dimensional Parameters ◽  
Theories Of Gravity ◽  
Alternative Theories ◽  
Black Hole Solutions

In this paper, we have presented an algorithm to generate various black hole solutions in general relativity and alternative theories of gravity. The algorithm involves few dimensional parameters that are assigned suitable values to specify the required black hole.

scholarly journals Cosmological Tests of Gravity

2019 ◽  
Vol 57 (1) ◽  
pp. 335-374 ◽  
Author(s):  
Pedro G. Ferreira
Keyword(s):  
General Relativity ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Alternative Theories Of Gravity ◽  
Systematic Uncertainties ◽  
Cosmological Observations ◽  
Theories Of Gravity ◽  
Tests Of Gravity ◽  
The Universe

Cosmological observations are beginning to reach a level of precision that allows us to test some of the most fundamental assumptions in our working model of the Universe. One such assumption is that gravity is governed by the theory of general relativity. In this review, we discuss how one might go about extending general relativity and how such extensions can be described in a unified way on large scales. This allows us to describe the phenomenology of modified gravity in the growth and morphology of the large-scale structure of the Universe. On smaller scales, we explore the physics of gravitational screening and how it might manifest itself in galaxies, clusters, and, more generally, in the cosmic web. We then analyze the current constraints from large-scale structure and conclude by discussing the future prospects of the field in light of the plethora of surveys currently being planned. Key results include the following: ▪ There are a plethora of alternative theories of gravity that are restricted by fundamental physics considerations. ▪ There is now a well-established formalism for describing cosmological perturbations in the linear regime for general theories of gravity. ▪ Gravitational screening can mask modifications to general relativity on small scales but may, itself, lead to distinctive signatures in the large-scale structure of the Universe. ▪ Current constraints on both linear and nonlinear scales may be affected by systematic uncertainties that limit our ability to rule out alternatives to general relativity. ▪ The next generation of cosmological surveys will dramatically improve constraints on general relativity, by up to two orders of magnitude.

scholarly journals FOURTH-ORDER GRAVITY AND EXPERIMENTAL CONSTRAINTS ON EDDINGTON PARAMETERS

2006 ◽  
Vol 21 (30) ◽  
pp. 2291-2301 ◽  
Author(s):  
S. CAPOZZIELLO ◽  
A. STABILE ◽  
A. TROISI
Keyword(s):  
Experimental Data ◽  
General Relativity ◽  
Alternative Theories Of Gravity ◽  
Third Order ◽  
Definitive Answer ◽  
Order Polynomial ◽  
Theories Of Gravity ◽  
Definition Of ◽  
Ppn Parameters ◽  
Alternative Theories

PPN-limit of alternative theories of gravity represents a still controversial matter of debate and no definitive answer has been provided, up to now, about this issue. By using the definition of the PPN-parameters γ and β in terms of f(R) theories of gravity, we show that a family of third-order polynomial theories, in the Ricci scalar R, turns out to be compatible with the PPN-limit and the deviation from General Relativity, theoretically predicted, can agree with experimental data.

scholarly journals Renormalizability of Alternative Theories of Gravity: Differences between Power Counting and Entropy Argument

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 148
Author(s):  
Francesco Bajardi ◽  
Francesco Bascone ◽  
Salvatore Capozziello
Keyword(s):  
General Relativity ◽  
Teleparallel Gravity ◽  
Power Counting ◽  
Alternative Theories Of Gravity ◽  
Spherically Symmetric ◽  
Asymptotic Safety ◽  
Renormalizable Theory ◽  
Theories Of Gravity ◽  
Working Out ◽  
Alternative Theories

It is well known that General Relativity cannot be considered under the standard of a perturbatively renormalizable quantum field theory, but asymptotic safety is taken into account as a possibility for the formulation of gravity as a non-perturbative renormalizable theory. Recently, the entropy argument has however stepped into the discussion claiming for a “no-go” to the asymptotic safety argument. In this paper, we present simple counter-examples, considering alternative theories of gravity, to the entropy argument as further indications, among others, on the possible flows in the assumptions on which the latter is based. We considered different theories, namely curvature-based extensions of General Relativity as f(R), f(G), extensions of teleparallel gravity as f(T), and Horava–Lifshitz gravity, working out the explicit spherically symmetric solutions in order to make a comparison between power counting and the entropy argument. Even in these cases, inconsistencies were found.

scholarly journals Scalarized black holes

2021 ◽  
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Burkhard Kleihaus ◽  
Jutta Kunz
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Alternative Theories Of Gravity ◽  
Gravitational Action ◽  
Theories Of Gravity ◽  
Bonnet Term ◽  
Alternative Theories ◽  
Black Hole Solutions

AbstractBlack holes represent outstanding astrophysical laboratories to test the strong gravity regime, since alternative theories of gravity may predict black hole solutions whose properties may differ distinctly from those of general relativity. When higher curvature terms are included in the gravitational action as, for instance, in the form of the Gauss–Bonnet term coupled to a scalar field, scalarized black holes result. Here we discuss several types of scalarized black holes and some of their properties.

scholarly journals TESTS OF GENERAL RELATIVITY AND ALTERNATIVE THEORIES OF GRAVITY USING GRAVITATIONAL WAVE OBSERVATIONS

2013 ◽  
Vol 22 (01) ◽  
pp. 1341012 ◽  
Author(s):  
K. G. ARUN ◽  
ARCHANA PAI
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Strong Field ◽  
Information Matrix ◽  
Simons Theory ◽  
Alternative Theories Of Gravity ◽  
Newtonian Theory ◽  
Theories Of Gravity ◽  
Model Independent ◽  
Alternative Theories

Gravitational wave (GW) observations of coalescing compact binaries will be unique probes of strong-field, dynamical aspects of relativistic gravity. We present a short review of various schemes proposed in the literature to test general relativity (GR) and alternative theories of gravity using inspiral waveforms. Broadly these schemes may be classified into two types: model dependent and model independent. In the model dependent category, GW observations are compared against a specific waveform model representative of a particular theory or a class of theories such as scalar-tensor theories, dynamical Chern–Simons theory and massive graviton theories. Model independent tests are attempts to write down a parametrized gravitational waveform where the free parameters take different values for different theories and (at least some of) which can be constrained by GW observations. We revisit some of the proposed bounds in the case of downscaled LISA configuration (eLISA) and compare them with the original LISA configuration. We also compare the expected bounds on alternative theories of gravity from ground-based and space-based detectors and find that space-based GW detectors can test GR and other theories of gravity with unprecedented accuracies. We then focus on a recent proposal to use singular value decomposition of the Fisher information matrix to improve the accuracies with which post-Newtonian theory can be tested. We extend those results to the case of space-based detector eLISA and discuss its implications.

scholarly journals Radioscience simulations in general relativity and in alternative theories of gravity

2012 ◽  
Vol 29 (23) ◽  
pp. 235027 ◽  
Author(s):  
A Hees ◽  
B Lamine ◽  
S Reynaud ◽  
M-T Jaekel ◽  
C Le Poncin-Lafitte ◽  
...  
Keyword(s):  
General Relativity ◽  
Alternative Theories Of Gravity ◽  
Theories Of Gravity ◽  
Alternative Theories
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