Fri - 05/26/23

Ergodic Concepts for a Self-Organizing Trivalent Spin Network

  • Authors: Christine C. Dantas (Astrophysics Division, INPE, Brazil)
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2305.16009
  • Abstract We consider, from a dynamical systems point of view, a frozen, planar trivalent spin network model in Loop Quantum Gravity (LQG) presenting self-organized criticality (SOC). We obtain a partition function for the domains of stability connecting gauge non-invariant avalanches, leading to an entropy formula for the asymptotic SOC state. We use this formalism to obtain the entropy of a $(2+1)$-dimensional (BTZ) black hole, and conjecture that this entropy reduces to the Bekenstein-Hawking entropy law by an appropriate adjustment of a potential function.

A reduced phase space quantisation of a model in Algebraic Quantum Gravity with polarised $T^3$ Gowdy symmetry

  • Authors: Kristina Giesel, Andreas Leitherer, David Winnekens
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2305.16237
  • Abstract We consider a reduced phase space quantisation of a model with $T^3$ Gowdy symmetry in which gravity has been coupled to Gaussian dust. We complete the quantisation programme in reduced loop quantum gravity (LQG) as well as algebraic quantum gravity (AQG) and derive a Schr"odinger-like equation with a physical Hamiltonian operator encoding the dynamics. Due to the classical symmetries of the physical Hamiltonian, the operators are quantised in a graph-preserving way in both cases – a difference to former models available in the literature. As a first step towards applications of the model in AQG, we consider an ansatz that we use to first construct zero volume states as specific solutions of the Schr"odiger-like equation. We then also find states with a vanishing action of the Euclidean part of the physical Hamiltonian and investigate the degeneracies these states experience via the action of the Lorentzian part of the physical Hamiltonian. The results presented here can be taken as a starting point for deriving effective models as well as analysing the dynamics numerically in future work.

There is no new related paper today

  1. [2305.16011] - Coördinate transformations, metrics and black hole features in the collapsed phase of EDT - Jan Smit

  2. [2305.16193] - 30 years in: Quo vadis generalized uncertainty principle? - Pasquale Bosso, Giuseppe Gaetano Luciano, Luciano Petruzziello, Fabian Wagner

  3. [2305.15470] - Gauge theory on twist-noncommutative spaces - Tim Meier, Stijn J. van Tongeren

  4. [2305.16028] - Information loss, mixing and emergent type III$_1$ factors - Keiichiro Furuya, Nima Lashkari, Mudassir Moosa, Shoy Ouseph

Thu - 05/25/23

There is no new related paper today

There is no new related paper today

  1. [2305.15232] - A vacuum solution of modified Einstein equations based on fractional calculus - A. Di Teodoro, E. Contreras

  2. [2305.15095] - Metrics and geodesics on fuzzy spaces - David Viennot

Wed - 05/24/23

There is no new related paper today

There is no new related paper today

Tue - 05/23/23

Introduction to Loop Quantum Gravity: Rovelli’s lectures on LQG

  • Authors: Pietropaolo Frisoni
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); Quantum Physics (quant-ph)
  • Arxiv link: https://arxiv.org/abs/2305.12215
  • Abstract These notes are a transcript of Carlo Rovelli’s lectures on Loop Quantum Gravity, given in Marseille in 2018, which (at present) can be entirely found on YouTube. I transcribed them in LaTeX in early 2020 as an exercise to get ready for my Ph.D. in LQG at Western University. This transcript is meant to be a (hopefully helpful) integration for the video version. I reported the order of the topics and the chronological structure exactly as presented by Rovelli throughout the course, primarily to facilitate the comparison. Each Section corresponds to a different Lecture. The parts written in textit are my additions. Sometimes in the text, I report references, which specify precisely the minute and the second of the corresponding video on YouTube, to very short historical digressions or excursus made during the lectures by Rovelli that I have not explicitly transcribed in these notes. Where appropriate, I took some figures from the book “Covariant Loop Quantum Gravity - An elementary introduction to Quantum Gravity and Spinfoam Theory” by Carlo Rovelli and Francesca Vidotto, to which I always refer by the term “the book” in the following. For what concerns the equations, where possible, I tried to write down the “correct” versions present within the book. Finally, I thank Carlo Rovelli himself for reviewing these notes. I apologize in advance for any errors, and I wish everyone a lot of fun!

Constraints on rotating self-dual black hole with quasi-periodic oscillations

  • Authors: Cheng Liu, Haiguang Xu, Hoongwah Siew, Tao Zhu, Qiang Wu, Yuanyuan Zhao
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
  • Arxiv link: https://arxiv.org/abs/2305.12323
  • Abstract An impressive feature of loop quantum gravity (LQG) is that it can elegantly resolve both the big bang and black hole singularities. By using the Newman-Janis algorithm, a regular and effective rotating self-dual black hole(SDBH) metric could be constructed, which alters the Kerr geometry with a polymeric function $P$ from the quantum effects of LQG geometry. In this paper, we investigate its impact on the frequency characteristics of the X-ray quasi-periodic oscillations(QPOs) from 5 X-ray binaries and contrast it with the existing results of the orbital, periastron precession and nodal precession frequencies within the relativistic precession model. We apply a Monte Carlo Markov Chain (MCMC) simulation to examine the possible LQG effects on the X-ray QPOs. We found that the best constraint result for the rotating self-dual geometry from LQG came from the QPOs of X-ray binary GRO J1655-40, which establish an upper bound on the polymeric function $P$ less than $8.6\times 10^{-4}$ at 95\% confidence level. This bound leads to a restriction on the polymeric parameter $\delta$ of LQG to be 0.24.

Introduction to Loop Quantum Gravity: Rovelli’s lectures on LQG

  • Authors: Pietropaolo Frisoni
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); Quantum Physics (quant-ph)
  • Arxiv link: https://arxiv.org/abs/2305.12215
  • Abstract These notes are a transcript of Carlo Rovelli’s lectures on Loop Quantum Gravity, given in Marseille in 2018, which (at present) can be entirely found on YouTube. I transcribed them in LaTeX in early 2020 as an exercise to get ready for my Ph.D. in LQG at Western University. This transcript is meant to be a (hopefully helpful) integration for the video version. I reported the order of the topics and the chronological structure exactly as presented by Rovelli throughout the course, primarily to facilitate the comparison. Each Section corresponds to a different Lecture. The parts written in textit are my additions. Sometimes in the text, I report references, which specify precisely the minute and the second of the corresponding video on YouTube, to very short historical digressions or excursus made during the lectures by Rovelli that I have not explicitly transcribed in these notes. Where appropriate, I took some figures from the book “Covariant Loop Quantum Gravity - An elementary introduction to Quantum Gravity and Spinfoam Theory” by Carlo Rovelli and Francesca Vidotto, to which I always refer by the term “the book” in the following. For what concerns the equations, where possible, I tried to write down the “correct” versions present within the book. Finally, I thank Carlo Rovelli himself for reviewing these notes. I apologize in advance for any errors, and I wish everyone a lot of fun!

  1. [2305.12549] - Higher-Derivative Quantum Gravity with Purely Virtual Particles: Renormalizability and Unitarity - Marco Piva

  2. [2305.12593] - The Vacuum Energy Problem in Quantum Gravity and the Masses of Elementary Particles - Djordje Minic

Mon - 05/22/23

There is no new related paper today

There is no new related paper today

  1. [2305.11185] - Repulsive gravity in regular black holes - Orlando Luongo, Hernando Quevedo

  2. [2305.11201] - Quasinormal Modes and Phase Structure of Regular $AdS$ Einstein-Gauss-Bonnet Black Holes - Yerlan Myrzakulov, Kairat Myrzakulov, Sudhaker Upadhyay, Dharm Veer Singh

  3. [2305.11224] - Quantum Gravity Background in Next-Generation Gravitational Wave Detectors - Mathew W. Bub, Yanbei Chen, Yufeng Du, Dongjun Li, Yiwen Zhang, Kathryn M. Zurek

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