Predictions of quantum gravity in inflationary cosmology: effects of the Weyl-squared term

Anselmi, Damiano; Bianchi, Eugenio; Piva, Marco

doi:10.1007/jhep07(2020)211

Cited by 41 publications

(121 citation statements)

References 41 publications

(67 reference statements)

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“…Purely virtual particles [22], or "fakeons", can be used to formulate a consistent theory of quantum gravity [7], which is experimentally testable thanks to its predictions in inflationary cosmology [23]. More generally, they can be used to solve the problem of ghosts in higher-derivatives theories.…”

Section: Jhep11(2021)030 1 Introductionmentioning

confidence: 99%

Diagrammar of physical and fake particles and spectral optical theorem

Anselmi

2021

J. High Energ. Phys.

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We prove spectral optical identities in quantum field theories of physical particles (defined by the Feynman iϵ prescription) and purely virtual particles (defined by the fakeon prescription). The identities are derived by means of purely algebraic operations and hold for every (multi)threshold separately and for arbitrary frequencies. Their major significance is that they offer a deeper understanding on the problem of unitarity in quantum field theory. In particular, they apply to “skeleton” diagrams, before integrating on the space components of the loop momenta and the phase spaces. In turn, the skeleton diagrams obey a spectral optical theorem, which gives the usual optical theorem for amplitudes, once the integrals on the space components of the loop momenta and the phase spaces are restored. The fakeon prescription/projection is implemented by dropping the thresholds that involve fakeon frequencies. We give examples at one loop (bubble, triangle, box, pentagon and hexagon), two loops (triangle with “diagonal”, box with diagonal) and arbitrarily many loops. We also derive formulas for the loop integrals with fakeons and relate them to the known formulas for the loop integrals with physical particles.

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Section: Jhep11(2021)030 1 Introductionmentioning

confidence: 99%

Diagrammar of physical and fake particles and spectral optical theorem

Anselmi

2021

J. High Energ. Phys.

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“…This issue might be remedied, for instance, by using the recently introduced fakeonprescription [49], where the effect on inflation is investigated in ref. [133]. See also [50][51][52][53] and the discussion in footnote 1.…”

Section: Jhep08(2021)016mentioning

confidence: 95%

Unified emergence of energy scales and cosmic inflation

Kubo

Kuntz

Lindner

et al. 2021

J. High Energ. Phys.

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In the quest for unification of the Standard Model with gravity, classical scale invariance can be utilized to dynamically generate the Planck mass MPl. However, the relation of Planck scale physics to the scale of electroweak symmetry breaking μH requires further explanation. In this paper, we propose a model that uses the spontaneous breaking of scale invariance in the scalar sector as a unified origin for dynamical generation of both scales. Using the Gildener-Weinberg approximation, only one scalar acquires a vacuum expectation value of υS ∼ (1016−17) GeV, thus radiatively generating $$ {M}_{\mathrm{P}1}\approx {\beta}_S^{1/2}{\upsilon}_S $$ M P 1 ≈ β S 1 / 2 υ S and μH via the neutrino option with right handed neutrino masses mN = yMυS ∼ 107 GeV. Consequently, active SM neutrinos are given a mass with the inclusion of a type-I seesaw mechanism. Furthermore, we adopt an unbroken Z2 symmetry and a Z2-odd set of right-handed Majorana neutrinos χ that do not take part in the neutrino option and are able to produce the correct dark matter relic abundance (dominantly) via inflaton decay. The model also describes cosmic inflation and the inflationary CMB observables are predicted to interpolate between those of R2 and linear chaotic inflationary model and are thus well within the strongest experimental constraints.

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“…(2) RG , not by the standard adiabatic and isocurvature perturbations R adiab and R iso . In the end, the predictions of the pure theory found in [33] turn out to be quite robust.…”

Section: Introductionmentioning

confidence: 91%

“…This can be done by first classicizing quantum gravity [31,32] and then quantizing the (projected) classical limit by means of the Bunch-Davies quantization condition. The consistency of this procedure on the FLRW background leads to the bound m χ > m φ /4 on the coefficients of the terms R 2 and C 2 [33], which makes the prediction on the tensor-to-scalar ratio r quite sharp (0.4 1000r 3 with 60 efoldings), at least in the case of single-field inflation.…”

Section: Introductionmentioning

confidence: 99%

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Perturbation Spectra and Renormalization-Group Techniques in Double-Field Inflation and Quantum Gravity Cosmology

Anselmi

2021

Preprint

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We study primordial cosmology with two scalar fields that participate in inflation at the same time, by coupling quantum gravity (i.e., the theory R + R 2 + C 2 with the fakeon prescription/projection for C 2 ) to a scalar field with a quadratic potential. We show that there exists a perturbative regime that can be described by an asymptotically de Sitter, cosmic RG flow in two couplings. Since the two scalar degrees of freedom mix in nontrivial ways, the adiabatic and isocurvature perturbations are not RG invariant on superhorizon scales. It is possible to identify the correct perturbations by using RG invariance as a guiding principle. We work out the resulting power spectra of the tensor and scalar perturbations to the NNLL and NLL orders, respectively. An unexpected consequence of RG invariance is that the theory remains predictive. Indeed, the scalar mixing affects only the subleading corrections, so the predictions of quantum gravity with single-field inflation are confirmed to the leading order.

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Predictions of quantum gravity in inflationary cosmology: effects of the Weyl-squared term

Cited by 41 publications

References 41 publications

Diagrammar of physical and fake particles and spectral optical theorem

Diagrammar of physical and fake particles and spectral optical theorem

Unified emergence of energy scales and cosmic inflation

Perturbation Spectra and Renormalization-Group Techniques in Double-Field Inflation and Quantum Gravity Cosmology

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