Fri - 11/22/24

**Title:

      Spinning Particle Dynamics and ISCO in Covariant Loop Quantum Gravity**  - **Authors:** Yongbin Du, Yunlong Liu, Xiangdong Zhang  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  In this paper, we investigate the motion of spinning particles in the background of covariant loop quantum gravity black holes, focusing on two distinct effective metric solutions. Both metrics incorporate a quantum parameter $\zeta$, which quantifies loop quantum corrections. When $\zeta$ approaches zero, the spacetime reduces to the classical Schwarzschild solution. Using the pole-dipole approximation, we derive the equations of motion for spinning particles, accounting for the spin-curvature coupling. Our analysis reveals significant deviations in the behavior of the Innermost Stable Circular Orbit (ISCO) due to quantum effects. In the first effective metric, as $\zeta$ increases, the ISCO's radial position shifts, and for sufficiently large values of $\zeta$ (greater than 4.55), the ISCO disappears, allowing particles to hover above the black hole or oscillate radially. In contrast, in the second metric, ISCOs persist even for large values of $\zeta$, albeit with a more restrictive spin range. These findings highlight the impact of loop quantum gravity corrections on the dynamics of spinning particles and provide insights into potential observational consequences for gravitational wave detections.

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Thu - 11/21/24

**Title:

      Traversable Wormholes Sourced by Dark Matter in Loop Quantum Cosmology**  - **Authors:** Marcos V. de S. Silva, G. Alencar, R. M. P. Neves, Celio R. Muniz  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  In this work, we investigate the existence of wormholes within the framework of Loop Quantum Cosmology, considering isotropic dark matter as the matter source. We examine three distinct density profiles and employ modified field equations along with stress-energy tensor conservation, applying suitable boundary conditions to derive traversable wormhole solutions. We confirm that each obtained solution meets the geometric requirements for wormholes and assess the regularity of these spacetimes by computing the Kretschmann scalar to ensure the absence of singularities. Through the stress-energy tensor, we analyze the conditions under which energy conditions may be violated in this model. We explore the geometry of these wormholes using embedding diagrams, and evaluate the stability of the solutions by examining the speed of sound. Lastly, we compute the amount of exotic matter necessary to sustain these structures using the Volume Integral Quantifier.

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Wed - 11/20/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Rips and regular future scenario with Holographic Dark Energy: A comprehensive look - I. Brevik, Maxim Khlopov, S.D. Odintsov, Alexander V. Timoshkin, Oem Trivedi

Tue - 11/19/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Cosmic inflation in an extended non-commutative foliated quantum gravity: the wave function of the universe - César A. Zen Vasconcellos, Peter O. Hess, José de Freitas Pacheco, Fridolin Weber, Benno Bodmann, Dimiter Hadjimichef, Geovane Naysinger, Rodrigo Fraga, João G.G. Gimenez, Marcelo Netz-Marzola, Moisés Razeira

Mon - 11/18/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Shadows of rotating black holes in effective quantum gravity - Zhenglong Ban, Jiawei Chen, Jinsong Yang

New papers last week