Archived weekly pre-prints 23-12-04

Authors: Beatriz Elizaga Navascués
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2311.18066
Abstract The dynamics of the expectation value of the volume is one of the key ingredients behind the replacement of the Big Bang singularity by a bounce in Loop Quantum Cosmology. As such, it is of great importance that this quantity is mathematically well-defined in the space of physical states of the theory. A number of caveats have been raised about such a definition entering in conflict with the quantum evolution of states, motivated by the situation found in quantum geometrodynamics. We show that there are ways around these caveats, all of which are related to the existence of quantization prescriptions leading to a nondegenerate curvature operator in Loop Quantum Cosmology. Furthermore, we explicitly check that there exist families of physical states for which the expectation value of the volume is actually finite under evolution. These include the Gaussian states traditionally used in investigations of the quantum bounce. Interestingly, the properties of the curvature operator that allow for such a good behavior of the volume are only possible thanks to the discreteness of the geometry characteristic of the loop quantization procedure.

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[2311.18238] - The Einstein-Hilbert Action for Entropically Dominant Causal Sets - Peter Carlip, Steve Carlip, Sumati Surya
[2311.18546] - Parametric resonance of gravitational waves in general scalar-tensor theories - Yi-Fu Cai, Guillem Domènech, Alexander Ganz, Jie Jiang, Chunshan Lin, Bo Wang
[2311.18290] - Constrained HRT Surfaces and their Entropic Interpretation - Xi Dong, Donald Marolf, Pratik Rath

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[2311.17151] - Lagrangian reverse engineering for regular black holes - Ana Bokulić, Edgardo Franzin, Tajron Jurić, Ivica Smolić
[2311.17199] - Renormalization group flows from the Hessian geometry of quantum effective actions - Yannick Kluth, Peter Millington, Paul Saffin
[2311.17526] - Combinatorial quantum gravity and emergent 3D quantum behaviour - Carlo A. Trugenberger

Authors: Ilkka Mäkinen
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2311.16648
Abstract We introduce a master constraint operator on the kinematical Hilbert space of loop quantum gravity representing a set of gauge conditions which classically fix the densitized triad to be diagonal. We argue that the master constraint approach provides a natural and systematic way of carrying out the quantum gauge-fixing procedure which underlies the model known as quantum-reduced loop gravity. The Hilbert space of quantum-reduced loop gravity is obtained as a particular space of solutions of the gauge-fixing master constraint operator. We give a concise summary of the fundamental structure of the quantum-reduced framework, and consider several possible extensions thereof, for which the master constraint formulation provides a convenient starting point. In particular, we propose a generalization of the standard Hilbert space of quantum-reduced loop gravity, which may be relevant in the application of the quantum-reduced model to physical situations in which the Ashtekar connection is not diagonal.

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[2311.16319] - Horizon-scale effects in astrophysical black holes from mass-dependent regulators - Jens Boos, Christopher D. Carone
[2311.16252] - Mock Modularity In CHL Models - Ajit Bhand, Ashoke Sen, Ranveer Kumar Singh
[2311.17023] - Reflected entropy in BCFTs on a black hole background - Debarshi Basu, Himanshu Chourasiya, Vinayak Raj, Gautam Sengupta

Authors: Daniele Oriti, Yi-Li Wang
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Arxiv link: https://arxiv.org/abs/2311.14377
Abstract We study the emergent dynamics of an anisotropic universe in the context of Group Field Theory condensate cosmology, with a scalar field playing the role of a relational clock. According to different definitions of ``isotropy’’, two anisotropic condensate states are considered and the Bianchi-like dynamics of cosmological anisotropic observables, as well as their quantum fluctuations, are analysed. We find that both anisotropic states become isotropic at late time, reproducing an effective Friedmann dynamics, while anisotropies give small but non-negligible contributions at earlier times, closer to the cosmic bounce.

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[2311.13633] - Open AdS/CFT via a Double Trace Deformation - Hao Geng
[2311.13636] - How to Build a Black Hole out of Instantons - Rishi Mouland
[2311.13742] - Extremal Black Hole Decay in de Sitter Space - Lars Aalsma, Jan Pieter van der Schaar, Manus Visser

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[2311.13138] - Effect of rainbow function on the structural properties of dark energy star - A. Bagheri Tudeshki, G. H. Bordbar, B. Eslam Panah
[2311.13264] - Gravitational repulsive effects in 3D regular black holes - Orlando Luongo, Hernando Quevedo, S. N. Sajadi
[2311.13358] - Irregular Fibonacci Conformal Blocks - Xia Gu, Babak Haghighat, Kevin Loo