Quasinormal modes from EFT of black hole perturbations with timelike scalar profile

Mukohyama, Shinji; Takahashi, Kazufumi; Tomikawa, Keitaro; Yingcharoenrat, Vicharit

doi:10.1088/1475-7516/2023/07/050

Cited by 13 publications

(7 citation statements)

References 99 publications

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“…Notice that, due to the symmetry of the background metric, only the above four components of the Einstein equation are independent. We see that when g M = 0, the background equations above reduce to the ones found in the case of scalar-tensor theories, where the kinetic term of the scalar field is assumed to be constant [53,55,73]. For g M ̸ = 0, we obtain additional contributions in front of the parameter c in the first two equations of (4.15), whereas the last two equations remain the same as in [53,55,73].…”

Section: Jcap03(2024)012mentioning

confidence: 72%

“…We see that when g M = 0, the background equations above reduce to the ones found in the case of scalar-tensor theories, where the kinetic term of the scalar field is assumed to be constant [53,55,73]. For g M ̸ = 0, we obtain additional contributions in front of the parameter c in the first two equations of (4.15), whereas the last two equations remain the same as in [53,55,73]. These background equations provide relations among the EFT coefficients, given the metric functions A(r) and B(r), and the gauge-field value q.…”

Section: Jcap03(2024)012mentioning

confidence: 84%

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Effective field theory of black hole perturbations in vector-tensor gravity

Aoki,

Gorji,

Mukohyama

et al. 2024

J. Cosmol. Astropart. Phys.

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We formulate the effective field theory (EFT) of vector-tensor gravity for perturbations around an arbitrary background with a timelike vector profile, which can be applied to study black hole perturbations. The vector profile spontaneously breaks both the time diffeomorphism and the U(1) symmetry, leaving their combination and the spatial diffeomorphism as the residual symmetries in the unitary gauge. We derive two sets of consistency relations which guarantee the residual symmetries of the EFT. Also, we provide the dictionary between our EFT coefficients and those of generalized Proca (GP) theories, which enables us to identify a simple subclass of the EFT that includes the GP theories as a special case. For this subclass, we consider the stealth Schwarzschild(-de Sitter) background solution with a constant temporal component of the vector field and study the decoupling limit of the longitudinal mode of the vector field, explicitly showing that the strong coupling problem arises due to vanishing sound speeds. This is in sharp contrast to the case of gauged ghost condensate, in which perturbations are weakly coupled thanks to certain higher-derivative terms, i.e., the scordatura terms. This implies that, in order to consistently describe this type of stealth solutions within the EFT, the scordatura terms must necessarily be taken into account in addition to those already included in the simple subclass.

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Section: Jcap03(2024)012mentioning

confidence: 72%

Section: Jcap03(2024)012mentioning

confidence: 84%

Effective field theory of black hole perturbations in vector-tensor gravity

Aoki,

Gorji,

Mukohyama

et al. 2024

J. Cosmol. Astropart. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…) . In table 5 we compare the dominant quasinormal modes, calculated using the analytic formula (27), and the accurate values calculated in [41]. We see that for small values of the parameter σ the analytic formula gives a good estimation of the frequencies even for small values of the multipole number ℓ.…”

Section: Black Holes In the Effective Field Theorymentioning

confidence: 93%

“…Here we will use the resultant wave like equation for the axial gravitational perturbations in the Effective Field Theory deduced in [41]. The deduction of the wave equation for the even gravitational as well as scalar, electromagnetic and Dirac perturbations are highly non-trivial in the Effective Field Theory, because all of them are characterized by their specific effective propagation speed and tortoise coordinate, so that we used here the case for which the wavelike equation is already known.…”

Section: Black Holes In the Effective Field Theorymentioning

confidence: 99%

Analytic expressions for quasinormal modes and grey-body factors in the eikonal limit and beyond

Konoplya,

Zhidenko

2023

Class. Quantum Grav.

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Although the WKB series converges only asymptotically and guarantees the exact result solely in the eikonal regime, we have managed to derive concise analytical expressions for the quasinormal modes and grey-body factors of black holes, expanding beyond the eikonal approximation. Remarkably, these expressions demonstrate unexpectedly strong accuracy. We suggest a comprehensive approach for deriving analytical expressions for grey-body factors and quasinormal modes at various orders beyond the eikonal approximation. Two cases are examined as examples: the Schwarzschild-de Sitter black hole and hairy black holes within the framework of Effective Field Theory. We have publicly shared a generic code that calculates analytical expressions for grey-body factors and quasinormal modes of spherical black holes.

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“…[53] and then applied to black hole perturbations in Refs. [54,67,68]. It would be intriguing to extend this EFT to incorporate our generalized disformal theories, which we leave for future work.…”

Section: Generalized Disformal Theoriesmentioning

confidence: 99%

Invertible disformal transformations with higher derivatives

2022

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Invertible disformal transformations serve as a useful tool to explore ghost-free scalar-tensor theories. In this paper, we construct a generalization of invertible disformal transformations that involves arbitrary higher-order covariant derivatives of the scalar field. As a result, we obtain a more general class of ghost-free scalar-tensor theories than ever. Notably, our generalization is such that matter fields can be consistently coupled to these theories without introducing an unwanted extra degree of freedom in the unitary gauge. I. INTRODUCTIONGeneral relativity (GR) has passed various gravitational experiments as well as cosmological observations and is now commonly accepted as the standard model of gravitation and cosmology. Nevertheless, there are several motivations to study modifications/extensions of GR. For instance, GR is expected to be a low-energy effective theory and should be modified at high energies. Also, extended gravitational theories serve as good candidates that can be tested against GR [1][2][3]. In general, modified gravity models involve additional degrees of freedom (DOFs) on top of the metric, of which scalar-tensor theories (i.e., those involving a single scalar field besides the metric) have been studied extensively. The most general class of scalar-tensor theories with second-order Euler-Lagrange equations is now known as the Horndeski class [4][5][6]. Note that the second-order nature of the Euler-Lagrange equations guarantees the absence of Ostrogradsky ghosts, i.e., unstable extra DOFs associated with higher-order equations of motion [7].A more general class of ghost-free scalar-tensor theories was constructed in Refs. [8][9][10] by imposing the degeneracy condition [8,[11][12][13][14][15] on the higher-derivative terms, and this class is called the degenerate higher-order scalar-tensor (DHOST) class. (See Refs. [16,17] for reviews.) The DHOST class consists of many subclasses, and one of them can be obtained by the (conformal or) disformal transformation [18][19][20] of the Horndeski class, which we call the disformal Horndeski (DH) class. Note in passing that a ghost-free theory is mapped to another ghost-free theory by the disformal transformation since it is invertible in general [21,22]. Interestingly, DHOST theories that lie outside the DH class are known to exhibit ghost/gradient instabilities (or otherwise the metric becomes nondynamical) on a cosmological background [23][24][25]. Therefore, when one applies the DHOST theories to phenomenology, one usually focuses on the DH class. It was then realized that the framework of ghost-free scalar-tensor theories can be further extended by requiring the degeneracy only in the unitary gauge where the time coordinate is chosen so that the scalar field is spatially uniform. Such an extension was dubbed the U-DHOST class [26], which is equivalent to spatially covariant gravity [27][28][29][30] in the unitary gauge. Note that the scalar field profile has to be timelike in order to be consistent with the unitary gauge. Away from th...

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Quasinormal modes from EFT of black hole perturbations with timelike scalar profile

Cited by 13 publications

References 99 publications

Effective field theory of black hole perturbations in vector-tensor gravity

Effective field theory of black hole perturbations in vector-tensor gravity

Analytic expressions for quasinormal modes and grey-body factors in the eikonal limit and beyond

Invertible disformal transformations with higher derivatives

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