Archived weekly pre-print 21-07-05

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[2107.00087] - The Swampland Conjectures: A bridge from Quantum Gravity to Particle Physics - Mariana Graña, Alvaro Herráez

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Authors: José Diogo Simão, Sebastian Steinhaus
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2106.15635
Abstract In this article we study the Conrady-Hnybida extension of the Lorentzian Engle-Pereira-Rovelli-Livine spin-foam model, which admits time-like cells rather than just space-like ones. Our focus is on the asymptotic analysis of the model’s vertex amplitude. We propose a new parameterisation for states associated to time-like 3-cells, from which we derive a closed-form expression for their amplitudes. This allows us to revisit the conditions under which critical points of the amplitudes occur, and we find Regge-like geometrical critical points in agreement with the literature. However, we find also evidence for non-geometrical points which are not dynamically suppressed without further assumptions; the model then does not strictly asymptote to the Regge action, contrary to what one would expect. We moreover prove Minkowski and rigidity theorems for Minkowskian polyhedra, extending the asymptotic analysis to non-simplicial spin-foams. Lastly, we present evidence that the so-called “Cosine Problem” is not present for 4-cells containing both space- and time-like 3-cells.

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[2106.15430] - Classical and quantum gravity with fractional operators - Gianluca Calcagni
[2106.14896] - Entanglement Wedge in Flat Holography and Entanglement Negativity - Debarshi Basu, Ashish Chandra, Vinayak Raj, Gautam Sengupta
[2106.14971] - TQFT at work for IR-renormalons, resurgence and Lefschetz decomposition - Mithat Ünsal

Authors: Mattia Villani
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2106.14188
Abstract We apply topspin network formalism to Loop Quantum Gravity in order to include in the theory the possibility of changes in the topology of spacetime. We apply this formalism to three toy models: with the first, we find that the topology can actually change due to the action of the Hamiltonian constraint and with the second we find that the final state might be a superposition of states with different topologies. In the third and last application, we consider an homogeneous and isotropic Universe, calculating the difference equation that describes the evolution of the system and which are the final topological states after the action of the Hamiltonian constraint. For this last case, we also calculate the transition amplitudes and probabilities from the initial to the final states.

Authors: Pietro Dona, Francesco Gozzini, Alessandro Nicotra
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2106.14672
Abstract We show that the Euclidean and Lorentzian EPRL vertex amplitudes of covariant Loop Quantum Gravity are related through a ``Wick rotation’’ of the real Immirzi parameter to purely imaginary values. Our result follows from the simultaneous analytic continuation of the algebras, group elements and unitary irreducible representations of the gauge groups $Spin(4)$ and $SL(2,\mathbb{C})$, applied to the decomposition of the two models in terms of $SU(2)$ invariants and booster functions.

Authors: Pietro Dona, Francesco Gozzini, Alessandro Nicotra
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2106.14672
Abstract We show that the Euclidean and Lorentzian EPRL vertex amplitudes of covariant Loop Quantum Gravity are related through a ``Wick rotation’’ of the real Immirzi parameter to purely imaginary values. Our result follows from the simultaneous analytic continuation of the algebras, group elements and unitary irreducible representations of the gauge groups $Spin(4)$ and $SL(2,\mathbb{C})$, applied to the decomposition of the two models in terms of $SU(2)$ invariants and booster functions.

[2106.13893] - Observational optical constraints of the Simpson-Visser black-bounce geometry - Khadije Jafarzade, Mahdi Kord Zangeneh, Francisco S. N. Lobo
[2106.13942] - Hawking-Page transition with reentrance and triple point in Gauss-Bonnet gravity - Yuan-zhang Cui, Wei Xu, Bin Zhu
[2106.14717] - BMS Algebra, Double Soft Theorems, and All That - Miguel Campiglia, Alok Laddha

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[2106.13793] - Teleparallel Gravity: From Theory to Cosmology - Sebastian Bahamonde, Konstantinos F. Dialektopoulos, Celia Escamilla-Rivera, Gabriel Farrugia, Viktor Gakis, Martin Hendry, Manuel Hohmann, Jackson Levi Said, Jurgen Mifsud, Eleonora Di Valentino
[2106.13376] - Exact solutions for scalars and spinors on quantized (Euclidean) $AdS_2$ and the correspondence principle - A. Pinzul, A. Stern