Fri - 10/08/21

There is no new related paper today

There is no new related paper today

  1. [2110.03069] - Rainbow Black Hole From Quantum Gravitational Collapse - Aliasghar Parvizi, Tomasz Pawłowski, Yaser Tavakoli, Jerzy Lewandowski

  2. [2110.03194] - Nonlinear definition of the shadowy mode in higher-order scalar-tensor theories - Antonio De Felice, Shinji Mukohyama, Kazufumi Takahashi

  3. [2110.03388] - Emergence of Minkowski-Spacetime by Simple Deterministic Graph Rewriting - Gabriel Leuenberger

  4. [2110.03129] - $α’$-corrections to Near Extremal Dyonic Strings and Weak Gravity Conjecture - Liang Ma, Yi Pang, H. Lü

  5. [2110.03188] - Spacing Statistics of Energy Spectra: Random Matrices, Black Hole Thermalization, and Echoes - Krishan Saraswat, Niayesh Afshordi

  6. [2110.03197] - Holography in de Sitter Space via Chern-Simons Gauge Theory - Yasuaki Hikida, Tatsuma Nishioka, Tadashi Takayanagi, Yusuke Taki

Thu - 10/07/21

Report on the session Loop Quantum Gravity: Cosmology and Black Holes of the 16th Marcel Grossmann Meeting

  • Authors: Jorge Pullin, Parampreet Singh
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
  • Arxiv link: https://arxiv.org/abs/2110.02242
  • Abstract We summarize the main results of 19 talks presented at the QG3 session (loop quantum gravity: cosmology and black holes) of the 16th Marcel Grossmann Meeting held online from July $5^{\mathrm{th}}$-10$^{\mathrm{th}}$, 2021.

Modified dispersion relations and a potential explanation of the EDGES anomaly

  • Authors: Saurya Das, Mitja Fridman, Gaetano Lambiase, Antonio Stabile, Elias C. Vagenas
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2110.02340
  • Abstract The Experiment to Detect the Global Epoch of Reionisation Signature (EDGES) collaboration has recently reported an important result related to the absorption signal in the Cosmic Microwave Background radiation spectrum. This signal corresponds to the red-shifted 21-cm line at $z \simeq 17.2$, whose amplitude is about twice the expected value. This represents a deviation of approximately $3.8\sigma$ from the predictions of the standard model of cosmology, i.e. the $\Lambda$CDM model. This opens a window for testing new physics beyond both the standard model of particle physics and the $\Lambda$CDM model. In this work, we explore the possibility of explaining the EDGES anomaly in terms of modified dispersion relations. The latter are typically induced in unified theories and theories of quantum gravity, such as String/M-theories and Loop Quantum Gravity. These modified dispersion relations affect the density of states per unit volume and thus the thermal spectrum of the Cosmic Microwave Background photons. The temperature of the 21-cm brightness temperature is modified accordingly giving a potential explanation of the EDGES anomaly.

There is no new related paper today

  1. [2110.02542] - Can we detect the quantum nature of weak gravitational fields? - Francesco Coradeschi, Antonia Micol Frassino, Thiago Guerreiro, Jennifer Rittenhouse West, Enrico Junior Schioppa

Wed - 10/06/21

There is no new related paper today

There is no new related paper today

  1. [2110.01785] - Induced quantum gravitational interaction between two objects with permanent quadrupoles in external gravitational fields - Yongshun Hu, Jiawei Hu, Hongwei Yu

  2. [2110.02133] - Strict deformation quantization of abelian lattice gauge fields - T.D.H. van Nuland

Tue - 10/05/21

Twisted geometry coherent states in all dimensional loop quantum gravity: I. Construction and Peakedness properties

  • Authors: Gaoping Long, Xiangdong Zhang, Cong Zhang
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Lattice (hep-lat); Mathematical Physics (math-ph)
  • Arxiv link: https://arxiv.org/abs/2110.01317
  • Abstract A new family of coherent states for all dimensional loop quantum gravity are proposed, which is based on the generalized twisted geometry parametrization of the phase space of $SO(D+1)$ connection theory. We prove that this family of coherent states provide an over-complete basis of the Hilbert space in which edge simplicity constraint is solved. Moreover, according to our explicit calculation, the expectation values of holonomy and flux operators with respect to this family of coherent states coincide with the corresponding classical values given by the labels of the coherent states, up to some gauge degrees of freedom. Besides, we study the peakedness properties of this family of coherent states, including the peakedness of the wave functions of this family of coherent states in holonomy, momentum and phase space representations. It turns out that the peakedness in these various representations and the (relative) uncertainty of the expectation values of the operators are well controlled by the semi-classical parameter $t$. Therefore, this family of coherent states provide a candidate for the semi-classical analysis of all dimensional loop quantum gravity.

Finiteness of spinfoam vertex amplitude with timelike polyhedra, and the full amplitude

  • Authors: Muxin Han, Wojciech Kaminski, Hongguang Liu
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2110.01091
  • Abstract This work focuses on Conrady-Hnybida’s 4-dimensional extended spinfoam model with timelike polyhedra, while we restrict all faces to be spacelike. Firstly, we prove the absolute convergence of the vertex amplitude with timelike polyhedra, when SU(1,1) boundary states are coherent states or the canonical basis, or their finite linear combinations. Secondly, based on the finite vertex amplitude and a proper prescription of the SU(1,1) intertwiner space, we construct the extended spinfoam amplitude on arbitrary cellular complex, taking into account the sum over SU(1,1) intertwiners of internal timelike polyhedra. We observe that the sum over SU(1,1) intertwiners is infinite for the internal timelike polyhedron that has at least 2 future-pointing and 2 past-pointing face-normals. In order to regularize the possible divergence from summing over SU(1,1) intertwiners, we develop a quantum cut-off scheme based on the eigenvalue of the ``shadow operator’’. The spinfoam amplitude with timelike internal polyhedra (and spacelike faces) is finite, when 2 types of cut-offs are imposed: one is imposed on $j$ the eigenvalue of area operator, the other is imposed on the eigenvalue of shadow operator for every internal timelike polyhedron that has at least 2 future-pointing and 2 past-pointing face-normals.

  1. [2110.00722] - Semiclassical black holes and horizon singularities - Pravin K. Dahal, Sebastian Murk, Daniel R. Terno

  2. [2110.01121] - Mimicking Black Holes in General Relativity - Thomas Berry

  3. [2110.01115] - Machine Learning Statistical Gravity from Multi-Region Entanglement Entropy - Jonathan Lam, Yi-Zhuang You

Mon - 10/04/21

There is no new related paper today

There is no new related paper today

  1. [2110.00008] - Flavor Symmetries and Automatic Enhancement in the 6d Supergravity Swampland - Mirjam Cvetic, Ling Lin, Andrew P. Turner

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