Polarization Modes of Gravitational Waves in Palatini Horndeski theory

Dong, Yu-Qi; Liu, Yu-Xiao

doi:10.48550/arxiv.2111.07352

Cited by 4 publications

(4 citation statements)

References 42 publications

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“…Landau damping occurs only if the latter allows for a subluminal phase velocity of the considered radiating degree of freedom, at least in some regions of the wavelengths spectrum. In this respect, an intriguing possibility is offered by further extensions of Horndeski theories, such as the teleparallel formulation [164,165] or the Palatini generalization [166], exhibiting a large variety of additional polarizations, both massive and massless, which could be, in principle, subject to kinetic damping phenomena.…”

Section: Discussionmentioning

confidence: 99%

The Role of Longitudinal Polarizations in Horndeski and Macroscopic Gravity: Introducing Gravitational Plasmas

2021

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We discuss some general and relevant features of longitudinal gravitational modes in Horndeski gravity and their interaction with matter media. Adopting a gauge-invariant formulation, we clarify how massive scalar and vector fields can induce additional transverse and longitudinal excitations, resulting in breathing, vector, and longitudinal polarizations. We review, then, the interaction of standard gravitational waves with a molecular medium, outlining the emergence of effective massive gravitons, induced by the net quadrupole moment due to molecule deformation. Finally, we investigate the interaction of the massive mode in Horndeski gravity with a noncollisional medium, showing that Landau damping phenomenon can occur in the gravitational sector as well. That allows us to introduce the concept of “gravitational plasma”, where inertial forces associated with the background field play the role of cold ions in electromagnetic plasma.

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Section: Discussionmentioning

confidence: 99%

The Role of Longitudinal Polarizations in Horndeski and Macroscopic Gravity: Introducing Gravitational Plasmas

2021

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“…Landau damping occurs only if the latter allows for a subluminal phase velocity of the considered radiating degree of freedom, at least in some regions of the wavelengths spectrum. In this respect, an intriguing possibility is offered by further extensions of Horndeski theories, such as the teleparallel formulation [152,153] or the Palatini generalization [154], exhibiting a large variety of additional polarizations, both massive and massless, which could be in principle subject to kinetic damping phenomena. We conclude by stressing that the achievement of this very result, i.e.…”

Section: Discussionmentioning

confidence: 99%

The role of longitudinal polarizations in Horndeski and macroscopic gravity: Introducing gravitational plasmas

Moretti,

Bombacigno,

Montani

2021

Preprint

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We discuss some general and relevant features of longitudinal gravitational modes in Horndeski gravity and their interaction with matter media. Adopting a gauge-invariant formulation we clarify how massive scalar and vector fields can induce additional transverse and longitudinal excitations, resulting in breathing, vector and longitudinal polarizations. We review, then, the interaction of standard gravitational waves with a molecular medium, outlining the emergence of effective massive gravitons, induced by the net quadrupole moment due to the molecule deformation. Finally, we investigate the interaction of the massive mode in Horndeski gravity with a noncollisional medium, showing that Landau damping phenomenon can occur in the gravitational sector as well. That allows us to introduce the concept of "gravitational plasma", where inertial forces associated to the background field play the role of cold ions in electromagnetic plasma.

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“…By coupling MAG to scalar field(s), one gets the so-called "metric-affine scalar-tensor theory" [56][57][58][59][60], which can be seen as an analogue of the scalar-tensor theory in Riemannian geometry. In [61][62][63], propagation of gravitational waves has been discussed, which gives constraints on the relevant theory. MAG also generates "gauge theories of gravity" by applying the Yang-Mills theory to gravity (see [64] for a review).…”

Section: Introductionmentioning

confidence: 99%

Spatially covariant gravity with nonmetricity

Yu,

Chen,

Gao

2024

Eur. Phys. J. C

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Scalar fields play an important role in constructing modified gravity theories. In the case of a single scalar field with timelike gradient, the corresponding Lagrangian in the unitary gauge takes the form of spatially covariant gravity (SCG), which is proved useful in analyzing and extending the generally covariant theories. In this work, we apply the SCG method to the scalar-nonmetricity theory, of which the Lagrangian is built of the nonmetricity tensor and a scalar field. We derive the 3+1 decomposition of the geometric quantities and especially covariant derivatives of the scalar field up to the third order in the presence of a nonvanishing nonmetricity tensor. By fixing the unitary gauge, the resulting Lagrangian takes the form of a SCG with nonmetricity, in which all the ingredients are spatial tensors. We then exhaust the scalar monomials of SCG with nonmetricity up to $$d=3$$ d = 3 with d the total number of derivatives. Since the disformation tensor plays as an auxiliary variable, we take the Lagrangian with $$d=2$$ d = 2 as an example to show that after solving the disformation tensor, we can get an effective SCG theory for the metric variables but with modified coefficients. Our results provides a novel approach to extending the scalar-nonmetricity theory.

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Polarization Modes of Gravitational Waves in Palatini Horndeski theory

Cited by 4 publications

References 42 publications

The Role of Longitudinal Polarizations in Horndeski and Macroscopic Gravity: Introducing Gravitational Plasmas

The Role of Longitudinal Polarizations in Horndeski and Macroscopic Gravity: Introducing Gravitational Plasmas

The role of longitudinal polarizations in Horndeski and macroscopic gravity: Introducing gravitational plasmas

Spatially covariant gravity with nonmetricity

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