Fri - 01/03/25

**Title:

      Computing the graph-changing dynamics of loop quantum gravity**  - **Authors:** Thiago L. M. Guedes, Guillermo A. Mena Marugán, Francesca Vidotto, Markus Müller  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  In loop quantum gravity (LQG), quantum states of the gravitational field are represented by labelled graphs called spinnetworks. Their dynamics can be described by a Hamiltonian constraint, which modifies the spinnetwork graphs. Fixed graph approximations of the dynamics have been extensively studied, but its full graph-changing action so far remains elusive. The latter, alongside the solutions of its constraint, are arguably the missing features to access physically correct quantum-relativistic phenomenology from canonical LQG. Here, we introduce the first numerical tool that implements graph-changing dynamics via the Hamiltonian constraint. We find new solutions to this constraint and show that some quantum-geometrical observables behave differently than in the graph-preserving truncation. This work aims at fostering a new era of numerical simulations in canonical LQG that, crucially, embrace the graph-changing aspects of its dynamics, laying aside debated approximations.

**Title:

      Properties of black hole exterior fermions in spinfoam**  - **Authors:** Ayanendu Dutta  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We discuss fermion tunneling from the black hole exterior to white hole exterior geometry using the spin foam technique in background-independent Loop Quantum Gravity. The fermion transition time is equal, longer, or shorter than the black hole tunneling time, depending on the Euclidean dihedral angle. For a locally pinched negative curvature, fermions accumulate in the black hole exterior region where the black hole has already emerged from the white hole. Conversely, in locally stretched positive curvature, fermions reach the white hole exterior prior to the black hole, indicating an Einstein-Rosen bridge-like geometry in black hole-to-white hole bounce.
  1. [] - Title: Effective Field Theory Calculation of LIGO-like Compton Scattering and Experiment Proposal for Graviton Detection - Noah M. MacKay

Thu - 01/02/25

**Title:

      Computing the graph-changing dynamics of loop quantum gravity**  - **Authors:** Thiago L. M. Guedes, Guillermo A. Mena Marugán, Francesca Vidotto, Markus Müller  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  In loop quantum gravity (LQG), quantum states of the gravitational field are represented by labelled graphs called spinnetworks. Their dynamics can be described by a Hamiltonian constraint, which modifies the spinnetwork graphs. Fixed graph approximations of the dynamics have been extensively studied, but its full graph-changing action so far remains elusive. The latter, alongside the solutions of its constraint, are arguably the missing features to access physically correct quantum-relativistic phenomenology from canonical LQG. Here, we introduce the first numerical tool that implements graph-changing dynamics via the Hamiltonian constraint. We find new solutions to this constraint and show that some quantum-geometrical observables behave differently than in the graph-preserving truncation. This work aims at fostering a new era of numerical simulations in canonical LQG that, crucially, embrace the graph-changing aspects of its dynamics, laying aside debated approximations.

**Title:

      Properties of black hole exterior fermions in spinfoam**  - **Authors:** Ayanendu Dutta  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We discuss fermion tunneling from the black hole exterior to white hole exterior geometry using the spin foam technique in background-independent Loop Quantum Gravity. The fermion transition time is equal, longer, or shorter than the black hole tunneling time, depending on the Euclidean dihedral angle. For a locally pinched negative curvature, fermions accumulate in the black hole exterior region where the black hole has already emerged from the white hole. Conversely, in locally stretched positive curvature, fermions reach the white hole exterior prior to the black hole, indicating an Einstein-Rosen bridge-like geometry in black hole-to-white hole bounce.
  1. [] - Title: Effective Field Theory Calculation of LIGO-like Compton Scattering and Experiment Proposal for Graviton Detection - Noah M. MacKay

Wed - 01/01/25

**Title:

      Computing the graph-changing dynamics of loop quantum gravity**  - **Authors:** Thiago L. M. Guedes, Guillermo A. Mena Marugán, Francesca Vidotto, Markus Müller  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  In loop quantum gravity (LQG), quantum states of the gravitational field are represented by labelled graphs called spinnetworks. Their dynamics can be described by a Hamiltonian constraint, which modifies the spinnetwork graphs. Fixed graph approximations of the dynamics have been extensively studied, but its full graph-changing action so far remains elusive. The latter, alongside the solutions of its constraint, are arguably the missing features to access physically correct quantum-relativistic phenomenology from canonical LQG. Here, we introduce the first numerical tool that implements graph-changing dynamics via the Hamiltonian constraint. We find new solutions to this constraint and show that some quantum-geometrical observables behave differently than in the graph-preserving truncation. This work aims at fostering a new era of numerical simulations in canonical LQG that, crucially, embrace the graph-changing aspects of its dynamics, laying aside debated approximations.

**Title:

      Properties of black hole exterior fermions in spinfoam**  - **Authors:** Ayanendu Dutta  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We discuss fermion tunneling from the black hole exterior to white hole exterior geometry using the spin foam technique in background-independent Loop Quantum Gravity. The fermion transition time is equal, longer, or shorter than the black hole tunneling time, depending on the Euclidean dihedral angle. For a locally pinched negative curvature, fermions accumulate in the black hole exterior region where the black hole has already emerged from the white hole. Conversely, in locally stretched positive curvature, fermions reach the white hole exterior prior to the black hole, indicating an Einstein-Rosen bridge-like geometry in black hole-to-white hole bounce.
  1. [] - Title: Effective Field Theory Calculation of LIGO-like Compton Scattering and Experiment Proposal for Graviton Detection - Noah M. MacKay

Tue - 12/31/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Good tachyons, bad bradyons: role reversal in Einstein-nonlinear-electrodynamics models - Marco A. A. de Paula, Haroldo C. D. Lima Junior, Pedro V. P. Cunha, Carlos A. R. Herdeiro, Luís C. B. Crispino

Mon - 12/30/24

**Title:

      Covariant LTB collapse in models of loop quantum gravity**  - **Authors:** Martin Bojowald, Erick I. Duque, Dennis Hartmann  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  Models of gravitational collapse provide important means to test whether non-classical space-time effects motivated for instance by quantum gravity can be realized in generic ways in physically relevant situations. Here, a detailed analysis of marginally bound Lemaitre-Tolman-Bondi space-times is given in emergent modified gravity, which in particular includes a covariant formulation of holonomy modifications usually considered in models of loop quantum gravity. As a result, generic collapse in this setting is shown to imply a physical singularity that removes the bouncing behavior seen in vacuum space-times with the same type of modifications.

There is no new related paper today

New papers last week