Inflation with massive spin-2 ghosts

Kubo, Jisuke; Kuntz, Jeffrey; Rezacek, Jonas; Saake, Philipp

doi:10.1088/1475-7516/2022/11/049

Cited by 5 publications

(5 citation statements)

References 52 publications

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“…Note that the recovery of the Planck scale by M 2 pl = ξ ϕ 2 requires ξ > 0. This result is consistent with previous studies within the same Jordan frame [15] or the Einstein frame [14].…”

Section: B Masses Of the Scalar Sectorsupporting

confidence: 94%

“…associated to the scalar degree of freedom of the metric perturbation and the scalar mode corresponding to the field that develops the vev, as it has been discussed in [15]. In the JHEP02(2023)232 limit where ξ −→ 0, the two scalar modes do not mix, and the square mass eigenvalues are just m 2 0 and m 2 S .…”

Section: B Masses Of the Scalar Sectormentioning

confidence: 92%

“…In general, the mixing between the gravitational scalar mode and φ cannot be neglected as we discuss in appendix B and it has been pointed out in refs [14,15]…”

mentioning

confidence: 99%

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Gravitational Coleman-Weinberg mechanism

Álvarez-Luna

Calle-Leal

Cembranos

et al. 2023

J. High Energ. Phys.

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The Coleman-Weinberg mechanism provides a procedure by which a scalar field, which initially has no mass parameters, acquires a mass due to the anomalous nature of scale symmetry. Loop corrections trigger a spontaneous symmetry breaking and the appearance of a non-trivial vacuum. We first review the basic example of the Coleman-Weinberg mechanism, scalar Quantum Electrodynamics, in a perturbative regime where the scalar particle becomes massive through photon loops. We then present the main results of this article, what we name the gravitational Coleman-Weinberg mechanism: we analyse the same effect in a gravitational theory without explicit energy scales at tree-level. Finally, we also study the mechanism for two scalar fields in the mentioned gravitational theory. We will derive the gravitational Coleman-Weinberg potentials, analyse the parameter space where we have a symmetry breaking, and obtain the value of the corresponding scalar masses.

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Section: B Masses Of the Scalar Sectorsupporting

confidence: 94%

Section: B Masses Of the Scalar Sectormentioning

confidence: 92%

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Gravitational Coleman-Weinberg mechanism

Álvarez-Luna

Calle-Leal

Cembranos

et al. 2023

J. High Energ. Phys.

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“…Of the scale invariant models cited in [19]- [42], the models of refs. [19-24, 28, 29, 31, 33, 34, 38-42] can be regarded as an extension of the Starobinsky model and in fact predict small values of r. However, only those of refs.…”

Section: Resultsmentioning

confidence: 99%

“…Similarly, if κ, the coefficient of the W µναβ W µναβ term in the Lagrangian (2.2), is small, this term has only a small effect on the inflationary parameters (see for instance refs. [20,33,39,42,[96][97][98] and also [99]), so that we will ignore it in the following discussion. Hence the effective Lagrangian for inflation in the Jordan frame can be written as…”

Section: Effective Action For Inflationmentioning

confidence: 99%

Scale invariant extension of the Standard Model: a nightmare scenario in cosmology

Aoki,

Kubo,

Yang

2024

J. Cosmol. Astropart. Phys.

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Inflationary observables of a classically scale invariant model, in which the origin of the Planck mass and the electroweak scale including the right-handed neutrino mass is chiral symmetry breaking in a QCD-like hidden sector, are studied. Despite a three-field inflation the initial-value-dependence is strongly suppressed thanks to a river-valley like potential. The model predicts the tensor-to-scalar ratio r of cosmological perturbations smaller than that of the R 2 inflation, i.e., 0.0044 ≳ r ≳ 0.0017 for e-foldings between 50 and 60: the model will be consistent even with a null detection at LiteBird/CMB-S4. We find that the non-Gaussianity parameter f NL is O(10-2), the same size as that of single-field inflation. The dark matter particles are the lightest Nambu-Goldstone bosons associated with chiral symmetry breaking, which are decay products of one of the inflatons and are heavier than 109 GeV with a strongly suppressed coupling with the standard model, implying that the dark matter will be unobservable in direct as well as indirect measurements.

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On the degrees of freedom of R2 gravity in flat spacetime

Hell,

Lüst,

Zoupanos

2024

J. High Energ. Phys.

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We study the degrees of freedom of R2 gravity in flat spacetime with two approaches. By rewriting the theory a la Stueckelberg, and implementing Lorentz-like gauges to the metric perturbations, we confirm that the pure theory propagates one scalar degree of freedom, while the full theory contains two tensor modes in addition. We then consider the degrees of freedom by directly examining the metric perturbations. We show that the degrees of freedom of the full theory match with those obtained with the manifestly covariant approach. In contrast, we find that the pure R2 gravity has no degrees of freedom. We show that a similar discrepancy between the two approaches appears also in a theory dual to the three-form, and appears due to the Lorentz-like gauges, which lead to the fictitious modes even after the residual gauge redundancy has been taken into account. At first sight, this implies a discontinuity between the full theory and the pure case. By studying the first-order corrections of the full R2 gravity beyond the linear regime, we show that at high-energies, both scalar and tensor degrees of freedom become strongly coupled. This implies that the apparent discontinuity of pure and full R2 gravity is just an artefact of the perturbation theory, and further supports the absence of degrees of freedom in the pure R2 gravity.

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Inflation with massive spin-2 ghosts

Cited by 5 publications

References 52 publications

Gravitational Coleman-Weinberg mechanism

Gravitational Coleman-Weinberg mechanism

Scale invariant extension of the Standard Model: a nightmare scenario in cosmology

On the degrees of freedom of R2 gravity in flat spacetime

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