Fri - 03/29/24

There is no new related paper today

There is no new related paper today

  1. [2403.18896] - A Celestial Dual for MHV Amplitudes - Walker Melton, Atul Sharma, Andrew Strominger, Tianli Wang

  2. [2403.18937] - Analyticity and the Unruh effect: a study of local modular flow - Jonathan Sorce

  3. [2403.19389] - Spin couplings as witnesses of Planck scale phenomenology - Pasquale Bosso, Fabrizio Illuminati, Luciano Petruzziello, Fabian Wagner

Thu - 03/28/24

Entanglement entropy of coherent intertwiner in loop quantum gravity

  • Authors: Gaoping Long, Qian Chen, Jinsong Yang
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2403.18020
  • Abstract In this paper, we carry out the entanglement calculations on the coherent intertwiners. We first consider the entanglement introduced by the group-averaging of the tensor-product type intertwiner on a four-valents vertex. The result shows that the entanglement is determined by the probability distribution of recoupling spin, and this probability distribution is a well-behaved peak for the highest (and lowest) weight states. Further, we calculated explicitly the entanglement on gauge-invariant coherent intertwiner with four legs. Our numerical results show that the shape of the semiclassical polyhedron described by the coherent intertwiner can be related to the entanglement; In other words, the entanglement is controlled by the face-angle of the semiclassical polyhedron. Finally, we extend our analytical calculation to the coherent intertwiners with arbitrary number of legs.

Exploring the pre-inflationary dynamics in loop quantum cosmology with a DBI scalar field

  • Authors: Abolhassan Mohammadi
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2403.18289
  • Abstract Loop quantum cosmology is a symmetry-reduced application of loop quantum gravity. The theory predicts a bounce for the universe at the Planck scale and resolves the singularity of standard cosmology. The dynamics is also governed by an effective Hamiltonian, which predicts a modified Friedmann equation containing the quadratic terms of the energy density. The term plays an essential role in the high energy regime, but the equations return to the standard form in the low energy regime. The evolution of the universe in the pre-inflationary period is studied in the framework of loop quantum cosmology, where the DBI scalar field is assumed to be the dominant component of the universe. Using the numerical method, we provide the evolution of the DBI field. The background evolution shows that there are three phases as: bouncing phase, transition phase and slow-roll inflationary phase. There is also a short period of super-inflation just at the beginning of the bounce phase. The field first climbs the potential and then reaches the turning point where $\dot{\phi}$ disappears and the potential energy becomes the dominant part of the energy density. This is the time when the slow roll inflation begins and the field slowly rolls down the potential. The results indicate that there are a few e-fold expansions in the bounce phase, about $N = $, and the universe experiences about $N = 59$ e-fold expansions in the slow-roll inflation phase.

Test the Loop Quantum Gravity Theory via the Lensing Effect

  • Authors: Lai Zhao, Meirong Tang, Zhaoyi Xu
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2403.18606
  • Abstract Recently, scholars such as Lewandowski, Ma, and Yang have successfully derived a quantum-corrected black hole model in loop quantum gravity (Phys.Rev.Lett.130.101501 (2023)), which is a modification of the Schwarzschild black hole. In this paper, we calculate the strong/weak gravitational lensing effects under the quantum-corrected black hole model, taking the supermassive black holes M87* and SgrA* as the subjects of study to explore the impact of the quantum correction parameter $\alpha$ on the positions of images and the Einstein ring. Our calculations show that in the case of strong gravitational lensing, the lensing coefficient $\bar{a}$ increases with an increase in the quantum correction parameter, while the deflection angle and the lensing coefficient $\bar{b}$ decrease with an increase in the quantum correction parameter. The quantum correction parameter $\alpha$ has a significant impact in the context of supermassive black holes. In weak gravitational lensing, the quantum correction parameter $\alpha$ plays a suppressive role. Our theoretical analysis suggests that with advancements in future astrophysical observation techniques, it might be possible to test loop quantum gravity theory using the gravitational lensing effect.

There is no new related paper today

  1. [2403.18005] - The Tale of Three Scales: the Planck, the Species, and the Black Hole Scales - Alek Bedroya, Cumrun Vafa, David H. Wu

  2. [2403.18333] - Quantum gravity of the Heisenberg algebra - Ahmed Almheiri, Akash Goel, Xu-Yao Hu

  3. [2403.18460] - Probing the quantum nature of gravity using a Bose-Einstein condensate; “Erste Abhandlung” - Soham Sen, Sunandan Gangopadhyay

  4. [2403.18772] - Non-local quantum field theory from doubly special relativity - J.J. Relancio, L. Santamaría-Sanz

Wed - 03/27/24

Loop Quantum Gravity effects on electromagnetic properties of charged leptons

  • Authors: João Paulo S. Melo, Mario J. Neves, Jefferson M. A. Paixão, José A. Helayël-Neto
  • Subjects: High Energy Physics - Theory (hep-th); High Energy Physics - Phenomenology (hep-ph)
  • Arxiv link: https://arxiv.org/abs/2403.17197
  • Abstract The efforts in this contribution consist in reassessing a modified Dirac equation that incorporates a $\gamma^0 \gamma_5$-Lorentz-symmetry violating (LSV) term induced as a Loop Quantum Gravity (LQG) effect. Originally, this equation has been applied and considered as a good scenario for describing a number of investigations on the flight time of cosmic photons and neutrinos, which suggests that the speed of light in vacuum, in connection with the geometry that describes a granular space-time, takes an energy-dependent form, e.g., $v(E) =1 \pm E/E_{\tiny{\textrm{LSV}}}$, with $E_{\tiny{\textrm{LSV}}} \approx 6,5 \times 10^{17}$ GeV for neutrinos. Once LQG provides a viable way to consistently understand this picture, we pursue an analysis of this effective Dirac equation to inspect some of its properties. These include: the derivation of the modified fermionic propagator, attainment of the Gordon decomposition of the vector current with minimal electromagnetic coupling to obtain information on the form factors, examination of the non-relativistic limit of the equation, evaluation of the spin- and velocity-dependent corrections to the Coulomb potential due to LQG effects, and the modified Hamiltonian in the low-relativistic regime. The study of the form factors may open up paths to set up bounds on the LQG parameters from the precision measurements of electromagnetic attributes of the charged leptons, such as their respective electric and magnetic dipole moments.

There is no new related paper today

Tue - 03/26/24

From loop quantum gravity to cosmology: the 2-vertex model

  • Authors: Álvaro Cendal, Iñaki Garay, Luis J. Garay
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2403.15320
  • Abstract We show that the U(N)-symmetry reduction of the loop-quantum-gravity truncation known as the 2-vertex model provides the effective improved dynamics of loop quantum cosmology with an arbitrary perfect barotropic fluid content.

There is no new related paper today

Mon - 03/25/24

From loop quantum gravity to cosmology: the 2-vertex model

  • Authors: Álvaro Cendal, Iñaki Garay, Luis J. Garay
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2403.15320
  • Abstract We show that the U(N)-symmetry reduction of the loop-quantum-gravity truncation known as the 2-vertex model provides the effective improved dynamics of loop quantum cosmology with an arbitrary perfect barotropic fluid content.

There is no new related paper today

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