A consistent scalar-tensor cosmology for inflation, dark energy and the Hubble parameter

Wang, C.H.-T.; Reid, James Andrew; Murphy, A. St. J.; Rodrigues, D.; Alawi, M. Al; Bingham, R.; Mendonça, J. T.; Davies, Trevor B.

doi:10.1016/j.physleta.2016.09.038

Cited by 5 publications

(3 citation statements)

References 36 publications

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“…The coupling to scalar fields in particular has wide implications since they go far beyond merely a form of matter. Scalar fields are responsible for generating mass through the Higgs mechanism, and inducing cosmic inflation as inflatons, may serve to resolve the problem of time [6,7], and provide models for a variety of problems in physics and cosmology [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Immirzi parameter without Immirzi ambiguity: Conformal loop quantization of scalar-tensor gravity

Veraguth

Wang

2017

Phys. Rev. D

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Conformal loop quantum gravity provides an approach to loop quantization through an underlying conformal structure i.e. conformally equivalent class of metrics. The property that general relativity itself has no conformal invariance is reinstated with a constrained scalar field setting the physical scale. Conformally equivalent metrics have recently been shown to be amenable to loop quantization including matter coupling. It has been suggested that conformal geometry may provide an extended symmetry to allow a reformulated Immirzi parameter necessary for loop quantization to behave like an arbitrary group parameter that requires no further fixing as its present standard form does. Here, we find that this can be naturally realized via conformal frame transformations in scalar-tensor gravity. Such a theory generally incorporates a dynamical scalar gravitational field and reduces to general relativity when the scalar field becomes a pure gauge. In particular, we introduce a conformal Einstein frame in which loop quantization is implemented. We then discuss how different Immirzi parameters under this description may be related by conformal frame transformations and yet share the same quantization having, for example, the same area gaps, modulated by the scalar gravitational field.

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Section: Introductionmentioning

confidence: 99%

Immirzi parameter without Immirzi ambiguity: Conformal loop quantization of scalar-tensor gravity

Veraguth

Wang

2017

Phys. Rev. D

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“…Our general framework may serve to clarify various conceptual issues encountered in the phenomenological approach to quantum gravity [26,[55][56][57][58][59][60], with firstprinciples insights, and to guide further analytical tools, mathematical techniques, and modelling methodologies for possible detections of quantum gravity effects in the laboratory [61] and observatory [62] on the ground or in space [4]. In the context of the cosmological stochastic gravitational waves, since the universe is considered spatially flat with a low entropy on exit from inflation [63], our theory may describe short-time graviton radiation and reception by a distribution of coherent states having potentially unexpected but important collective properties including quantum nonlinearity, nonlocality, and entanglement [17,18]. In this regard, the theoretical framework reported here has recently been applied and further extended to address the possible detection of stochastic gravitational waves using correlated atoms [46] and potential observation of spacetime fluctuations through gravitational lensing [64].…”

Section: Discussionmentioning

confidence: 99%

Quantum coherence, radiance, and resistance of gravitational systems

Oniga

Wang

2017

Phys. Rev. D

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We develop a general framework for the open dynamics of an ensemble of quantum particles subject to spacetime fluctuations about the flat background. An arbitrary number of interacting bosonic and fermionic particles are considered. A systematic approach to the generation of gravitational waves in the quantum domain is presented that recovers known classical limits in terms of the quadrupole radiation formula and backreaction dissipation. Classical gravitational emission and absorption relations are quantized into their quantum field theoretical counterparts in terms of the corresponding operators and quantum ensemble averages. Certain arising consistency issues related to factor ordering have been addressed and resolved. Using the theoretical formulation established here with numerical simulations in the quantum regime, we discuss potential new effects including decoherence through the spontaneous emission of gravitons and collectively amplified radiation of gravitational waves by correlated quantum particles.

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“…We expected that this gravitational theory should involve a spin-2 graviton and its fermionic spin 3/2 gravitino companion particle. However, initial survey results at CERN using the TLAS detector [8], confirmed by recent postings, indicate no significant deviation from the Standard Model at 13 TeV, implying that the mass symmetry is badly broken; the mass-energies of the superpartners (if they exist) are possibly much larger than initially thought and limit their ability to control loop divergence. This leaves open the possibility of other potentially finite but more algebraic approaches including noncommutative geometry [9,10], and modified theories of gravity such as scalar-tensor gravitation [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Unitary Representations of the Translational Group Acting as Local Diffeomorphisms of Space-Time

Moffat¹,

Oniga²,

Cht³

2017

J Phys Math

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We continue to develop further a new mathematical approach to the quantisation of general field theories such as general relativity and modified gravity. Treating quantum fields as fibre bundles, we discuss operators acting on each fibre that generate a 'Fibre Algebra'. The algebras of two types of operators are considered in detail, namely observables as generic physical variables and more specialised quantum operators suitable for describing particles, symmetries and transformations. We then introduce quantum states of these operators and examine their properties. By establishing a link between the commutativity and group cohomology of the translational group as a local gauge group, we show that this leads to unitary representations. of the local gauge group of diffeomorphisms under very general topological conditions; as well the construction of generalised symmetric quantum states invariant under this group action. Discussion of these results in the context of loop quantum gravity and other current theories highlights constraints on the local nature of space-time.

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A consistent scalar-tensor cosmology for inflation, dark energy and the Hubble parameter

Cited by 5 publications

References 36 publications

Immirzi parameter without Immirzi ambiguity: Conformal loop quantization of scalar-tensor gravity

Immirzi parameter without Immirzi ambiguity: Conformal loop quantization of scalar-tensor gravity

Quantum coherence, radiance, and resistance of gravitational systems

Unitary Representations of the Translational Group Acting as Local Diffeomorphisms of Space-Time

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