Scale invariance, unimodular gravity and dark energy

Shaposhnikov, Mikhail; Zenhäusern, Daniel

doi:10.1016/j.physletb.2008.11.054

Cited by 245 publications

(318 citation statements)

References 43 publications

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“…Two ingredients of a potential UV completion of the Standard Model + gravity were conjectured in Refs. [29,30], namely (i) an exact, but spontaneously broken, quantum scale-invariance and (ii) the absence of particles with masses larger than the electroweak scale. In this framework, physical scales appear as the consequence of the spontaneous breaking of scale invariance and are proportional to the vacuum expectation value of an extra scalar field-the dilaton.…”

Section: B Reliability Of the Computation Of Radiative Correctionsmentioning

confidence: 99%

Living beyond the edge: Higgs inflation and vacuum metastability

2015

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The measurements of the Higgs mass and top Yukawa coupling indicate that we live in a very special universe, at the edge of the absolute stability of the electroweak vacuum. If fully stable, the Standard Model (SM) can be extended all the way up to the inflationary scale and the Higgs field, nonminimally coupled to gravity with strength ξ, can be responsible for inflation. We show that the successful Higgs inflation scenario can also take place if the SM vacuum is not absolutely stable. This conclusion is based on two effects that were overlooked previously. The first one is associated with the effective renormalization of the SM couplings at the energy scale M P =ξ, where M P is the Planck scale. The second one is a symmetry restoration after inflation due to high temperature effects that leads to the (temporary) disappearance of the vacuum at Planck values of the Higgs field.

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Section: B Reliability Of the Computation Of Radiative Correctionsmentioning

confidence: 99%

Living beyond the edge: Higgs inflation and vacuum metastability

2015

Self Cite

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“…The scalar spectral index n s and the tensor-to-scalar ratio r are given by 14) where N denotes the number of e-folds, and the signs +(−) should be used for the positivefield inflation and −(+) for negative-field inflation. We see that (2.14) predicts somewhat different behaviour of n s and r for the positive-field and negative-field inflation scenarios.…”

Section: Jhep05(2015)065mentioning

confidence: 99%

“…If ξ S,H ∼ 1, naturalness implies f 0 < ∼ 10 −8 . This bound can be relaxed by performing a more complete discussion at the light of the RGE for ξ H [39]: 14) where · · · denote beyond-the-SM terms. We see that the ξ couplings can naturally acquire two special values:…”

Section: Jhep05(2015)065mentioning

confidence: 99%

Dynamically induced Planck scale and inflation

Kannike

Hütsi

Pizza

et al. 2015

J. High Energ. Phys.

158

136

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Theories where the Planck scale is dynamically generated from dimensionless interactions provide predictive inflationary potentials and super-Planckian field variations. We first study the minimal single field realisation in the low-energy effective field theory limit, finding the predictions n s ≈ 0.96 for the spectral index and r ≈ 0.13 for the tensor-toscalar ratio, which can be reduced down to ≈ 0.04 in presence of large couplings. Next we consider agravity as a dimensionless quantum gravity theory finding a multifield inflation that converges towards an attractor trajectory and predicts n s ≈ 0.96 and 0.003 < r < 0.13, interpolating between the quadratic and Starobinsky inflation. These theories relate the smallness of the weak scale to the smallness of inflationary perturbations: both arise naturally because of small couplings, implying a reheating temperature of 10 7−9 GeV. A measurement of r by Keck/Bicep3 would give us information on quantum gravity in the dimensionless scenario.

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“…It is thus of interest to investigate a quantum theory of unimodular gravity. Unimodular gravity in both its quantum and classical form has sparked considerable interest since it was originally proposed [3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Jhep04(2015)096mentioning

confidence: 99%

The Renormalization Group flow of unimodular f(R) gravity

Eichhorn

2015

J. High Energ. Phys.

129

101

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Unimodular gravity is classically equivalent to General Relativity. This equivalence extends to actions which are functions of the curvature scalar. At the quantum level, the dynamics could differ. Most importantly, the cosmological constant is not a coupling in the unimodular action, providing a new vantage point from which to address the cosmological constant fine-tuning problem. Here, a quantum theory based on the asymptotic safety scenario is studied, and evidence for an interacting fixed point in unimodular f (R) gravity is found. We study the fixed point and its properties, and also discuss the compatibility of unimodular asymptotic safety with dynamical matter, finding evidence for its compatibility with the matter degrees of freedom of the Standard Model.

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Scale invariance, unimodular gravity and dark energy

Cited by 245 publications

References 43 publications

Living beyond the edge: Higgs inflation and vacuum metastability

Living beyond the edge: Higgs inflation and vacuum metastability

Dynamically induced Planck scale and inflation

The Renormalization Group flow of unimodular f(R) gravity

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