Spin-foam model for gravity coupled to massless scalar field

Kisielowski, Marcin; Lewandowski, Jerzy

doi:10.1088/1361-6382/aafcc0

Cited by 14 publications

(10 citation statements)

References 54 publications

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“…There are also some other recent results based on the simplicity of this Hamiltonian (see e.g. [47,76,77]. However as is mentioned in Section 6.3, the semiclassical limit of the scalar curvature operator has not yet been checked in the literature for the most general situation.…”

Section: Singularity Resolution and Bouncementioning

confidence: 97%

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Effective dynamics from coherent state path integral of full loop quantum gravity

Han

Liu

2020

Phys. Rev. D

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A new routine is proposed to relate Loop Quant Cosmology (LQC) to Loop Quantum Gravity (LQG) from the perspective of effective dynamics. We derive the big-bang singularity resolution and big bounce from the first principle of full canonical LQG. Our results are obtained in the framework of the reduced phase space quantization of LQG. As a key step in our work, we derive with coherent states a new discrete path integral formula of the transition amplitude generated by the physical Hamiltonian. The semiclassical approximation of the path integral formula gives an interesting set of effective equations of motion (EOMs) for full LQG. When solving the EOMs with homogeneous and isotropic ansatz, we reproduce the LQC effective dynamics in µ 0 -scheme. The solution replaces the big-bang singularity by a big bounce. In the end, we comment on the possible relation between theμ-scheme of effective dynamics and the continuum limit of the path integral formula. arXiv:1910.03763v2 [gr-qc] 23 Dec 20191 The result is also valid in the case of an infinite space. 2 E(γ) and V(γ) denote the set of edges and vertices in γ.

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Section: Singularity Resolution and Bouncementioning

confidence: 97%

“…It should shed light on the relation between canonical LQG and Spinfoam formulation. Interestingly in the scenario of gravity coupled to scalar field and AALM Hamiltonian, this path integral formula should be the coherent state representation of the spinfoam model in [47] if their model was defined with a non-graph-changing Hamiltonian.…”

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confidence: 99%

Effective dynamics from coherent state path integral of full loop quantum gravity

Han

Liu

2020

Phys. Rev. D

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“…Let us also note that although the analysis is focused on finding eigenstates of the scalar constraint operator in the homogeneous-isotropic sector, the results have important impact on the spin-foam amplitudes we proposed in [26]. Our analysis in particular implies that a history of a state in H j cube is described by states in H j cube .…”

Section: B the Outlook For Numerical Calculationsmentioning

confidence: 97%

Homogeneous-isotropic sector of loop quantum gravity: new approach

Kisielowski

2019

Preprint

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“…Operationally, we use these additional degrees of freedom to break the symmetry over the vertex-labels at an effective level only, achieving distinguishability only for a special class of quantum states and in a physically motivated approximation. For simplicity we consider, as additional degrees of freedom, a minimally coupled free massless scalar field λ discretized along the geometric data on the graphs (and simplicial complexes) associated to GFT quantum states, in analogy with the approach of [43,56] for defining a relational dynamics in the GFT condensate cosmology, and based on the analysis of scalar matter coupled to quantum gravity in GFT [57] and canonical LQG and spin foam models [58,59]. The GFT field thus turns into φ(g, λ) ∈ L 2 (G d /G×R), and the canonical commutation relations of eq.…”

Section: Jhep07(2021)052 7 Effective Distinguishability Of Verticesmentioning

confidence: 99%

Quantum gravity states, entanglement graphs and second-quantized tensor networks

Colafranceschi

Oriti

2021

J. High Energ. Phys.

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In recent years, the import of quantum information techniques in quantum gravity opened new perspectives in the study of the microscopic structure of spacetime. We contribute to such a program by establishing a precise correspondence between the quantum information formalism of tensor networks (TN), in the case of projected entangled-pair states (PEPS) generalised to a second-quantized framework, and group field theory (GFT) states, and by showing how, in this quantum gravity approach, discrete spatial manifolds arise as entanglement patterns among quanta of space, having a dual representation in terms of graphs and simplicial complexes. We devote special attention to the implementation and consequences of the label independence of the graphs/networks, corresponding to the indistinguishability of the space quanta and representing a discrete counterpart of the diffeomorphism invariance of a consistent quantum gravity formalism. We also outline a relational setting to recover distinguishability of graph/network vertices at an effective and physical level, in a partial semi-classical limit of the theory.

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Spin-foam model for gravity coupled to massless scalar field

Abstract: A spin-foam model is derived from the canonical model of Loop Quantum Gravity coupled to a massless scalar field. We generalized to the full theory the scheme first proposed in the context of Loop Quantum Cosmology by Ashtekar, Campiglia and Henderson, later developed

Cited by 14 publications

References 54 publications

Effective dynamics from coherent state path integral of full loop quantum gravity

Effective dynamics from coherent state path integral of full loop quantum gravity

Homogeneous-isotropic sector of loop quantum gravity: new approach

Quantum gravity states, entanglement graphs and second-quantized tensor networks

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