On the geometrical interpretation of scale-invariant models of inflation

Karananas, Georgios K.; Rubio, Javier

doi:10.1016/j.physletb.2016.08.037

Cited by 71 publications

(78 citation statements)

References 33 publications

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“…In cosmology there are global [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] or local [28][29][30][31][32][33][34][35][36][37][38][39] scale invariant alternatives to gravity with spontaneous breaking that generates the Planck scale by a non-minimal coupling.…”

Section: Motivationmentioning

confidence: 99%

Weyl R2 inflation with an emergent Planck scale

Ghilencea

2019

J. High Energ. Phys.

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We study inflation in Weyl gravity. The original Weyl quadratic gravity, based on Weyl conformal geometry, is a theory invariant under Weyl symmetry of (gauged) local scale transformations. In this theory Planck scale (M ) emerges as the scale where this symmetry is broken spontaneously by a geometric Stueckelberg mechanism, to Einstein-Proca action for the Weyl "photon" (of mass near M ). With this action as a "low energy" broken phase of Weyl gravity, long-held criticisms of the latter (due to non-metricity) are avoided. In this context, inflation with field values above M is natural, since this is just a phase transition scale from Weyl gravity (geometry) to Einstein gravity (Riemannian geometry), where the massive Weyl photon decouples. We show that inflation in Weyl gravity coupled to a scalar field has results close to those in Starobinsky model (recovered for vanishing non-minimal coupling), with a mildly smaller tensor-to-scalar ratio (r). Weyl gravity predicts a specific, narrow range 0.00257 ≤ r ≤ 0.00303, for a spectral index n s within experimental bounds at 68%CL and e-folds number N = 60. This range of values will soon be reached by CMB experiments and provides a test of Weyl

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Section: Motivationmentioning

confidence: 99%

Weyl R2 inflation with an emergent Planck scale

Ghilencea

2019

J. High Energ. Phys.

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“…Such scale invariant theories have to generate all dimensionfull scales through spontaneous breaking of the symmetry, including the Planck scale and the electroweak breaking scale associated with the BEH boson. To generate a period of inflation it is also necessary for the spontaneous scale symmetry breaking to give rise to the inflation scale and it has been shown that this is possible in the context of a model with two scalar fields non-minimally coupled to the Ricci scalar, R [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Such models can naturally lead to an acceptable period of inflation and, for the case in which one scalar is identified with the BEH boson, are similar to "Higgs" inflation [22].…”

Section: Introductionmentioning

confidence: 99%

Scale-independent R2 inflation

et al. 2019

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Weyl (scale) invariant theories of scalars and gravity can generate all mass scales spontaneously. In this paper we study a particularly simple version -scale invariant R 2 gravity -and show that, during an inflationary period, it leads to fluctuations which, for a particular parameter choice, are almost indistinguishable from normal R 2 inflation. Current observations place tight constraints on the primary coupling constant of this theory and predict a tensor to scalar ratio, 0.0033 > r > 0.0026, which is testable with the next generation of cosmic microwave background experiments.

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“…As shown in Ref. [29][30][31] poles of kinetic term correspond to stretching of the scalar potential around the pole and therefore such theories are the natural source of flat inflationry potentials. For λ = λ 2 and in the n → ∞ limit one finds 17) which is very similar to the kinetic term for of the α-attractors [20], where the kinetic term of a scalar field ψ is equal to (∂ψ) 2 …”

Section: Equivalence To α Attractorsmentioning

confidence: 91%

Multi-phase induced inflation in theories with non-minimal coupling to gravity

Artymowski

Lalak

Lewicki

2017

J. Cosmol. Astropart. Phys.

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Abstract. In this paper we investigate the induced inflation with two flat regions: one Starobinsky-like plateau in big field regime and one shorter plateau around the saddle point of the Einstein frame potential. This multi-phase inflationary scenario can be used to solve the problem of classical cosmology. The inflation at the saddle-point plateau is consistent with the data and can have arbitrarily low scale. The results can be useful in the context of the Higgs-Axion relaxation and in a certain limit they are equivalent to the α-attractors.

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On the geometrical interpretation of scale-invariant models of inflation

Cited by 71 publications

References 33 publications

Weyl R2 inflation with an emergent Planck scale

Weyl R2 inflation with an emergent Planck scale

Scale-independent R2 inflation

Multi-phase induced inflation in theories with non-minimal coupling to gravity

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