Gravitational wave constraints on spatial covariant gravities

Zhu, Tong; Zhang, Wen; Wang, Anzhong

doi:10.48550/arxiv.2211.04711

Cited by 4 publications

(6 citation statements)

References 58 publications

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“…The case with β ν = 2 can arise from the spatial covariant gravities [55,91] and the Hořava-Lifshtz gravity with mixed derivative coupling [37]. This case corresponds to a specific…”

Section: β ν =mentioning

confidence: 99%

“…The case with β μ = 2 can arise from a large number of Lorentz-violating theories of gravity, including the chiral Weyl gravity [93], spatial covariant gravities [55,91], Hořava-Lifshitz gravity [32,33,35], diffeomorphism/Lorentz violating linear gravity in the standard model extension [45,46], consistent four-dimensional Einstein-Gauss-Bonnet gravity [61,94,95], Lorentz-violating Weyl gravity [96], etc. This case corresponds to a nonlinear dispersion relation of GWs.…”

Section: β μ =mentioning

confidence: 99%

See 1 more Smart Citation

Power spectra and circular polarization of primordial gravitational waves with parity and Lorentz violations

Li,

Zhu,

Zhao

et al. 2024

J. Cosmol. Astropart. Phys.

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The violations of parity and Lorentz symmetries in gravity can change the propagating properties of gravitational waves (GWs) in the cosmological background, which can arise from a large number of parity- and Lorentz-violating theories. In this paper, through a systematic parametrization for characterizing possible derivations from the standard GW propagation in general relativity, we study both the parity- and Lorentz-violating effects on the power spectra and the polarization of the primordial gravitational waves (PGWs) during the slow-roll inflation. To this end, we calculate explicitly the power spectrum and the corresponding circular polarization of the PGWs analytically by using the uniform asymptotic approximation. It is shown that the new contributions to power spectra contain two parts, one from the parity-violating terms and the other from the Lorentz-violating terms. While the Lorentz-violating terms can only affect the overall amplitudes of PGWs, the parity-violating terms induce nonzero circular polarization of PGWs, i.e., the left-hand and right-hand polarization modes of GWs have different amplitudes.

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“…The case with β ν = 2 can arise from the spatial covariant gravities [55,91] and the Hořava-Lifshtz gravity with mixed derivative coupling [37]. This case corresponds to a specific…”

Section: β ν =mentioning

confidence: 99%

Section: β μ =mentioning

confidence: 99%

Power spectra and circular polarization of primordial gravitational waves with parity and Lorentz violations

Li,

Zhu,

Zhao

et al. 2024

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…A large class of SCG Lagrangians without any scalar degree of freedom has been investigated in [17,18] and applied in the study of cosmology and black holes [19][20][21][22]. 1 Additionally, constraints from gravitational waves on SCG have been explored in [28][29][30][31], from which one can see that SCG provides a broad framework to study various modified gravity theories in a unifying manner.…”

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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“…Other recent studies on parity violating gravities can be found in Refs. [22][23][24][25][26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Irregular universe in the Nieh-Yan modified teleparallel gravity

Li¹,

Rao²

2023

Preprint

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The Nieh-Yan modified teleparallel gravity is a model which modifies the general relativity equivalent teleparallel gravity by a coupling between the Nieh-Yan density and an axion-like field. This model predicts parity violations in the gravitational waves if the axion-like field has a non-trivial background, and more importantly it is ghost free and avoids the pathologies presented in other parity-violating gravity models. The cosmological dynamics and perturbations of the Nieh-Yan modified teleparallel gravity have been investigated in detail, but all these previous investigations rely on the symmetry requirement that in the background universe both the metric and affine connection are homogeneous and isotropic. In this paper we relax the symmetry constraint on the connection and leave it arbitrary at the beginning, after all the cosmological principle only needs the metric of the background spacetime to meet the symmetry requirement. We find a new flat universe solution for the Nieh-Yan modified teleparallel gravity, for which the background dynamics itself is unchanged but the perturbations around it present a new feature that the scalar and tensor perturbations are coupled together at the linear level. The implications of this peculiar feature in primordial perturbations from inflation are also discussed.

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Gravitational wave constraints on spatial covariant gravities

Cited by 4 publications

References 58 publications

Power spectra and circular polarization of primordial gravitational waves with parity and Lorentz violations

Power spectra and circular polarization of primordial gravitational waves with parity and Lorentz violations

Spatially covariant gravity with nonmetricity

Irregular universe in the Nieh-Yan modified teleparallel gravity

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