Fri - 11/24/23

There is no new related paper today

There is no new related paper today

  1. [2311.13138] - Effect of rainbow function on the structural properties of dark energy star - A. Bagheri Tudeshki, G. H. Bordbar, B. Eslam Panah

  2. [2311.13264] - Gravitational repulsive effects in 3D regular black holes - Orlando Luongo, Hernando Quevedo, S. N. Sajadi

  3. [2311.13358] - Irregular Fibonacci Conformal Blocks - Xia Gu, Babak Haghighat, Kevin Loo

Thu - 11/23/23

There is no new related paper today

There is no new related paper today

  1. [2311.13138] - Effect of rainbow function on the structural properties of dark energy star - A. Bagheri Tudeshki, G. H. Bordbar, B. Eslam Panah

  2. [2311.13264] - Gravitational repulsive effects in 3D regular black holes - Orlando Luongo, Hernando Quevedo, S. N. Sajadi

  3. [2311.13358] - Irregular Fibonacci Conformal Blocks - Xia Gu, Babak Haghighat, Kevin Loo

Wed - 11/22/23

Constraints from solar system tests on a covariant loop quantum black hole

  • Authors: Ruo-Ting Chen, Shulan Li, Li-Gang Zhu, Jian-Pin Wu
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2311.12270
  • Abstract Recently, a covariant spherically symmetric model of a black hole within the framework of loop quantum gravity (LQG), characterized by a quantum parameter $r_0$ or $\lambda$, has been proposed. To derive constraints on the LQG-corrected parameter, we explore observational constraints imposed on $r_0$ and $\lambda$ through investigations of the light deflection, the Shapiro time delay, the precession of perihelia, and the geodetic precession test. Among these constraints, the tightest one arises from the Shapiro time delay measured by the Cassini mission, yielding an upper constraint of approximately $10^{-5}$.

There is no new related paper today

  1. [2311.12286] - Thermodynamics for regular black holes as intermediate thermodynamic states and quasinormal frequencies - Bai-Hao Huang, Han-Wen Hu, Liu Zhao

  2. [2311.12113] - Shedding black hole light on the emergent string conjecture - Ivano Basile, Dieter Lust, Carmine Montella

  3. [2311.12121] - Scramblon loops - Douglas Stanford, Shreya Vardhan, Shunyu Yao

Tue - 11/21/23

Revisiting quantum black holes from effective loop quantum gravity

  • Authors: Geeth Ongole, Parampreet Singh, Anzhong Wang
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2311.10166
  • Abstract We systematically study a family of loop quantizations for the classical Kruskal spacetimes using the effective description motivated from loop quantum gravity for four generic parameters, $c_o, m, \delta_b$ and $\delta_c$, where the latter two denote the polymerization parameters which capture the underlying quantum geometry. We focus on the family where polymerization parameters are constant on dynamical trajectories, and of which the Ashtekar-Olmedo-Singh (AOS) and Corichi-Singh (CS) models appear as special cases. We study general features of singularity resolution in all these models due to quantum gravity effects and analytically extend the solutions across the white hole (WH) and black hole (BH) horizons to the exterior. We find that the leading term in the asymptotic expansion of the Kretschmann scalar is $r^{-4}$. However, for AOS and CS models black holes with masses greater than solar mass the dominant term behaves as $r^{-6}$ for the size of the observable universe and {our analysis can be used to phenomenologically constrain the choice of parameters for other models.} In addition, one can uniquely fix the parameter $c_o$ by requiring that the Hawking temperature at the BH horizon to the leading order be consistent with its classical value for a macroscopic BH. Assuming that the BH and WH masses are of the same order, we are able to identify a family of choices of $\delta_b$ and $\delta_c$ which share all the desired properties of the AOS model.

Emergent modified gravity coupled to scalar matter

  • Authors: Martin Bojowald, Erick I. Duque
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2311.10693
  • Abstract Emergent modified gravity presents a new set of generally covariant gravitational theories in which the space-time metric is not directly given by one of the fundamental fields. A metric compatible with the modified dynamics of gravity is instead derived from covariance conditions for space-time in canonical form. This paper presents a significant extension of existing vacuum models to the case of a scalar field coupled to emergent modified gravity in a spherically symmetric setting. Unlike in previous attempts for instance in models of loop quantum gravity, it is possible to maintain general covariance in the presence of modified gravity-scalar couplings. In general, however, the emergent space-time metric depends not only on the phase-space degrees of freedom of the gravitational part of the coupled theory, but also on the scalar field. Matter therefore directly and profoundly affects the geometry of space-time, not only through the well-known dynamical coupling of stress-energy to curvature as in Einstein’s equation, but even on a kinematical level before equations of motion are solved. This paper introduces further physical requirements that may be imposed for a reduction of modified theories to more specific classes, in some cases eliminating certain modifications that would be possible in a vacuum situation. With minimal coupling, results about the removal of classical black-hole singularities in vacuum emergent modified gravity are found to be unstable under the inclusion of matter, but alternative modifications exist in which singularities are removed even in the presence of matter. Emergent modified gravity is seen to provide a large class of new scalar-tensor theories with second-order field equations.

There is no new related paper today

  1. [2311.10564] - Unification of Decoupling Limits in String and M-theory - Chris D. A. Blair, Johannes Lahnsteiner, Niels A. J. Obers, Ziqi Yan

  2. [2311.10565] - Worldsheet Formalism for Decoupling Limits in String Theory - Joaquim Gomis, Ziqi Yan

Mon - 11/20/23

Revisiting quantum black holes from effective loop quantum gravity

  • Authors: Geeth Ongole, Parampreet Singh, Anzhong Wang
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2311.10166
  • Abstract We systematically study a family of loop quantizations for the classical Kruskal spacetimes using the effective description motivated from loop quantum gravity for four generic parameters, $c_o, m, \delta_b$ and $\delta_c$, where the latter two denote the polymerization parameters which capture the underlying quantum geometry. We focus on the family where polymerization parameters are constant on dynamical trajectories, and of which the Ashtekar-Olmedo-Singh (AOS) and Corichi-Singh (CS) models appear as special cases. We study general features of singularity resolution in all these models due to quantum gravity effects and analytically extend the solutions across the white hole (WH) and black hole (BH) horizons to the exterior. We find that the leading term in the asymptotic expansion of the Kretschmann scalar is $r^{-4}$. However, for AOS and CS models black holes with masses greater than solar mass the dominant term behaves as $r^{-6}$ for the size of the observable universe and {our analysis can be used to phenomenologically constrain the choice of parameters for other models.} In addition, one can uniquely fix the parameter $c_o$ by requiring that the Hawking temperature at the BH horizon to the leading order be consistent with its classical value for a macroscopic BH. Assuming that the BH and WH masses are of the same order, we are able to identify a family of choices of $\delta_b$ and $\delta_c$ which share all the desired properties of the AOS model.

Emergent modified gravity coupled to scalar matter

  • Authors: Martin Bojowald, Erick I. Duque
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2311.10693
  • Abstract Emergent modified gravity presents a new set of generally covariant gravitational theories in which the space-time metric is not directly given by one of the fundamental fields. A metric compatible with the modified dynamics of gravity is instead derived from covariance conditions for space-time in canonical form. This paper presents a significant extension of existing vacuum models to the case of a scalar field coupled to emergent modified gravity in a spherically symmetric setting. Unlike in previous attempts for instance in models of loop quantum gravity, it is possible to maintain general covariance in the presence of modified gravity-scalar couplings. In general, however, the emergent space-time metric depends not only on the phase-space degrees of freedom of the gravitational part of the coupled theory, but also on the scalar field. Matter therefore directly and profoundly affects the geometry of space-time, not only through the well-known dynamical coupling of stress-energy to curvature as in Einstein’s equation, but even on a kinematical level before equations of motion are solved. This paper introduces further physical requirements that may be imposed for a reduction of modified theories to more specific classes, in some cases eliminating certain modifications that would be possible in a vacuum situation. With minimal coupling, results about the removal of classical black-hole singularities in vacuum emergent modified gravity are found to be unstable under the inclusion of matter, but alternative modifications exist in which singularities are removed even in the presence of matter. Emergent modified gravity is seen to provide a large class of new scalar-tensor theories with second-order field equations.

There is no new related paper today

  1. [2311.10564] - Unification of Decoupling Limits in String and M-theory - Chris D. A. Blair, Johannes Lahnsteiner, Niels A. J. Obers, Ziqi Yan

  2. [2311.10565] - Worldsheet Formalism for Decoupling Limits in String Theory - Joaquim Gomis, Ziqi Yan

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