Cited by 191Noncommutative and Quantum Gravity TheoriesRelativity and Gravitational TheoryBlack Holes and Theoretical Physics

The DOI matches its Crossref record; 40 of the 40 references it cites were found in a registry or an index; 1 of the 28 sources its claims cite were checked for support.

Spin-foams for all loop quantum gravity

Open access
Kamiński, Wojciech, Kisielowski, Marcin, Lewandowski, Jerzy·2010·Classical and Quantum Gravity

Abstract

The simplicial framework of Engle–Pereira–Rovelli–Livine spin-foam models is generalized to match the diffeomorphism invariant framework of loop quantum gravity. The simplicial spin-foams are generalized to arbitrary linear 2-cell spin-foams. The resulting framework admits all the spin-network states of loop quantum gravity, not only those defined by triangulations (or cubulations). In particular, the notion of embedded spin-foam we use allows us to consider knotting or linking spin-foam histories. Also the main tools, the vertex structure and the vertex amplitude, are naturally generalized to an arbitrary valency case. The correspondence between all the SU (2) intertwiners and the SU (2)× SU (2) EPRL intertwiners is proved to be 1–1 in the case of the Barbero–Immirzi parameter |γ| ⩾ 1.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The paper generalizes EPRL spin-foams from simplicial complexes to arbitrary linear 2-cell complexes and embedded spin-foams, so that all LQG spin-network states—including knotted/linked graphs and arbitrary valency—can have spin-foam histories. It also proves a 1-1 correspondence between SU(2) intertwiners and SU(2) × SU(2) EPRL intertwiners for |γ| ≥ 1, except when the EPRL co-domain is trivial and the domain is non-trivial.

Key findings

  • The simplicial EPRL spin-foam framework is generalized to arbitrary linear 2-cell spin-foams and embedded spin-foams, admitting all spin-network states of loop quantum gravity, not only those defined by triangulations or cubulations; knotting or linking spin-foam histories are allowed.
  • The vertex structure and vertex amplitude are generalized to arbitrary valency; a vertex is encoded by the spin-network induced on the boundary of its neighbourhood.
  • The correspondence between all SU(2) intertwiners and SU(2) × SU(2) EPRL intertwiners is proved to be 1-1 for |γ| ≥ 1, unless the co-domain of the EPRL map is trivial and the domain is non-trivial.
  • An n-valent Barrett-Crane intertwiner is defined equivalently to earlier definitions, and the EPRL intertwiner is generalized; in the limit γ → ±∞ the EPRL intertwiner becomes the BC intertwiner.

Methods

  • Theoretical/mathematical construction within loop quantum gravity and spin-foam models; no empirical data or sample are used.
  • Foams are defined as oriented linear 2-cell complexes with boundary; faces are coloured by irreducible representations and internal edges by intertwiners, inducing a boundary spin-network; vertex traces, spin-foam traces, and embedded spin-foams are then defined.
  • The injectivity proof for the map I ↦ ι_EPRL(I) uses the spin composition map and mathematical induction.

Limitations

  • Stated: “We do not study the FK intertwiners in the γ > 1 in this paper.”
  • Stated: the discussion notes that the limits γ → 0, ±1, ±∞ are mathematically well defined but the model “seems to be losing its key properties”; for example, γ → ±∞ gives the BC intertwiner with 0 or 1 dimension per vertex, γ → ±1 gives an SU(2) BF amplitude, and γ → 0 does not resemble a topological theory.
  • Evident from the text: no numerical, observational, or semiclassical/convergence validation of the generalized amplitudes is presented; the work is a formal mathematical construction.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1088/0264-9381/27/9/095006

Cites

40 of 40 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

20 No basis given · 16 Not checked yet · 13 Own interpretation · 1 Couldn’t confirm · accuracy not yet measured

Verify all 27 references — free account

Show all 36 claims

  • It may state two separate claims as one. 8
  • Probably not a substantial claim. 6
14 of 14
  • The paper relies on this without support.

    Loop quantum gravity is a quantum theory of gravitational field with all its local degrees of freedom and is not a discretized theory.

    “Loop quantum gravity is a quantum theory of gravitational field with all its local degrees of freedom. This is not a discretized theory.”
  • The paper relies on this without support.

    The kinematical observables labelled by curves and 2-surfaces form a complete set for the continuum theory.

    “The (kinematical) observables labelled by curves and 2-surfaces form a complete set for the continuum theory.”
  • The paper relies on this without support.

    Loop quantum gravity is a diffeomorphism invariant theory of fields on manifolds.

    “Secondly, LQG is a diffeomorphism invariant theory of fields on manifolds.”
  • The paper relies on this without support.

    The diffeomorphisms play a crucial role in loop quantum gravity and are responsible for the diversity of embedded graphs and spin-networks labelling the quantum states.

    “The diffeomorphisms play a crucial role in LQG. They are responsible for the diversity of embedded graphs and spin-networks labelling the quantum states.”
  • The paper relies on this without support.

    In the LQG canonical framework, there is no justified way to restrict the graphs to those dual to triangulations of the underlying 3-manifold.

    “In the LQG canonical framework, whose quantum states are labelled by embedded spin-networks, there is no justified way to restrict the graphs to those dual to triangulations of the underlying 3-manifold.”
  • The paper relies on this without support.

    Loop quantum gravity admits knotted and linked graphs.

    “In particular, LQG admits knotted and linked graphs.”
  • The authors state this as an assumption.

    The spin-foams are histories of the embedded spin-network functions defined within the framework of the diffeomorphism invariant quantization of the theory of connections.

    “We combine it in below with the assumption that the spin-foams are histories of the embedded spin-network functions defined within the framework of the diffeomorphism invariant quantization of the theory of connections (see Section II).”
  • The paper relies on this without support.

    The self dual action defines the same Einstein's (Euclidean) gravity.

    “That is very strange, taking into account that the self dual action still defines the same Einstein's (Euclidean) gravity.”
8 of 8

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Citations

Cites

Show all 40 references

Research works printed but not linked: 1

  1. Barbero F, 1996, Phys. Rev., 51, 55075510

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Metadata

Authors
Kamiński, W., Kisielowski, M., & Lewandowski, J.
Affiliations
  • University of Warsaw (PL)
  • Pennsylvania State University (US)
Venue
Classical and Quantum Gravity
Published
2010-03-19
Volume
27
Issue
9
Pages
095006
ISSN
  • 0264-9381 (ISSN-L)
  • 1361-6382
OpenAlex
W2096508020
Cited by
191
References
40
Citations by year
2026: 4 · 2025: 1 · 2024: 8 · 2023: 13 · 2022: 8 · 2021: 9 · 2020: 7 · 2019: 13 · 2018: 17 · 2017: 7 · 2016: 12 · 2015: 7 · 2014: 16 · 2013: 24 · 2012: 21
FWCI
15.20
Type
journal article
Language
en
Open access
Locations
  • Classical and Quantum Gravity (publishedVersion)
  • arXiv (Cornell University) (publishedVersion)
  • HAL (submittedVersion, other-oa)
  • Trinity's Access to Research Output (TARA) (Trinity College Dublin) (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Physical Sciences › Physics and Astronomy › Nuclear and High Energy Physics › Noncommutative and Quantum Gravity Theories
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Relativity and Gravitational Theory
  • Physical Sciences › Physics and Astronomy › Nuclear and High Energy Physics › Black Holes and Theoretical Physics
Keywords
spin foam models, loop quantum gravity, EPRL model, spin network states, vertex amplitude, Barbero-Immirzi parameter, diffeomorphism invariance

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