Wed - 02/04/26

There is no new related paper today

There is no new related paper today

  1. [] - Title: Charged Superradiant Instability of Spherically Symmetric Regular Black Holes in de Sitter Spacetime: Time- and Frequency-Domain Analysis - Yizhi Zhan, Hengyu Xu, Haowei Chen, Shao-Jun Zhang

Tue - 02/03/26

There is no new related paper today

**Title:

      Causal spinfoam vertex for 4d Lorentzian quantum gravity**  - **Authors:** Eugenio Bianchi, Chaosong Chen, Mauricio Gamonal  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We introduce a new causal spinfoam vertex for $4$d Lorentzian quantum gravity. The causal data are encoded in Toller $T$-matrices, which add to Wigner $D$-matrices $T^{(+)}+T^{(-)}=D$, and for which we provide a Feynman $\mathrm{i}\varepsilon$ representation. We discuss how the Toller poles cancel in the EPRL vertex, how the Livine-Oriti model is obtained in the Barrett-Crane limit, and how spinfoam causal data are distinct from Regge causal data. In the large-spin limit, we show that only Lorentzian Regge geometries with causal data compatible with the spinfoam data are selected, resulting in a single exponential $\exp(+\mathrm{i}\, S_{\mathrm{Regge}}/\hbar)$ and a new form of causal rigidity.
  1. [] - Title: Scattering sections from regular black holes immersed in perfect fluid dark matter - Omar Pedraza, L. A. López, Isaac Fernández

Mon - 02/02/26

**Title:

      Elementary blocks of Loop Quantum Gravity**  - **Authors:** Mehdi Assanioussi, Etera R. Livine  - **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 embark on the vast program of integrating the dynamics of Loop Quantum Gravity (LQG). Adopting the strategy of decomposing spin network states into small blocks of (quantum) geometry which can later be glued back together, we focus on the more modest objective of studying the Hamiltonian dynamics on the {\it candy graph}, that is two nodes linked together by an arbitrary number of edges and also having open edges. This elementary setting allows both for curvature to develop around the bulk loops and both non-trivial boundary data and dynamics on the open edges. We study this system at the classical level and leave the detailed of its quantum regime for future investigation. Working on a single loop with two external legs, we show how the LQG Hamiltonian ansatz reduces to a pair of non-linear differential equations, similar to the cubic Schrödinger equation, on the areas carried by the bulk links. We provide analytical solutions to this evolution equation, identifying oscillatory modes (bounded modes) and divergent modes (similar to bouncing cosmological trajectories). This provides an explicit template for future investigations of LQG dynamics on more sophisticated spin network architecture built as arrays of candy graphs.

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