Fri - 07/04/25

**Title:

      Primordial regular black holes as all the dark matter. III. Covariant canonical quantum gravity models**  - **Authors:** Marco Calzà, Davide Pedrotti, Guan-Wen Yuan, Sunny Vagnozzi  - **Subjects:** 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/](https://arxiv.org/abs/)  - **Abstract**  In earlier companion papers, we showed that non-singular primordial black holes (PBHs) could account for all the dark matter (DM) over a significantly wider mass range compared to Schwarzschild PBHs. Those studies, mostly based on phenomenological metrics, are now extended by considering the quantum-corrected space-time recently proposed by Zhang, Lewandowski, Ma and Yang (ZLMY), derived from an effective canonical (loop) quantum gravity approach explicitly enforcing general covariance. Unlike the BHs considered earlier, ZLMY BHs are free from Cauchy horizons, and are hotter than their Schwarzschild counterparts. We show that this higher temperature boosts the evaporation spectra of ZLMY PBHs, tightening limits on their abundance relative to Schwarzschild PBHs and shrinking the asteroid mass window where they can constitute all the DM, a result which reverses the earlier trend, but rests on firmer theoretical ground. While stressing the potential key role of quantum gravity effects in addressing the singularity and DM problems, our study shows that working within a consistent theoretical framework can strongly affect observational predictions.

**Title:

      Renormalization group flows in area-metric gravity**  - **Authors:** Johanna Borissova, Bianca Dittrich, Astrid Eichhorn, Marc Schiffer  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We put forward the first analysis of renormalization group flows in an area-metric theory, motivated by spin-foam quantum gravity. Area-metric gravity contains the well-known length-metric degrees of freedom of standard gravity as well as additional shape-mismatching degrees of freedom. To be phenomenologically viable, the shape-mismatching degrees of freedom have to decouple under the renormalization group flow towards lower scales. We test this scenario by calculating the renormalization group flow of the masses and find that these are in general even more relevant than dictated by their canonical scaling dimension. This generically results in masses which are large compared to the Planck mass and thereby ensure the decoupling of shape-mismatching degrees of freedom. In addition, the latter come in a left-handed and right-handed sector. We find that parity symmetry does not emerge under the renormalization group flow. Finally, we extract the renormalization group flow of the Immirzi parameter from this setup and find that its beta function features zeros at vanishing as well as at infinite Immirzi parameter.

Thu - 07/03/25

**Title:

      Bouncing Bianchi Models with Deformed Commutation Relations**  - **Authors:** Gabriele Barca, Steffen Gielen  - **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 study the anisotropic Bianchi I and Bianchi II models in vacuum in the framework of deformed commutation relations (DCRs). Working in a parametrisation of the spatial metric by a volume and two anisotropy variables, we propose modified Poisson brackets that for the volume alone reproduce the bounce dynamics of effective loop quantum cosmology (LQC), with additional modifications for anisotropy degrees of freedom. We derive effective Friedmann equations and observe cosmological bounces both in Bianchi I and Bianchi II. For Bianchi II, we find that the cosmological bounce now interacts with the usual reflection seen in the Kasner indices in various interesting ways, in close similarity again with what had been seen in LQC. This suggests that the DCR framework could model more general quantum-gravity inspired bounce scenarios in a relatively straightforward way.

There is no new related paper today

  1. [] - Title: The Crossed Product, Modular (Tomita) Dynamics and its Role in the Transition of Type $III$ to Type $II_{\infty}$ v.Neumann Algebras and Connections to Quantum Gravity - Manfred Requardt

Wed - 07/02/25

There is no new related paper today

There is no new related paper today

  1. [] - Title: Tidal Stretching and Compression in Black Bounce Backgrounds - T. M. Crispim, Marcos V. de S. Silva, G. Alencar, Diego Sáez-Chillón Gómez

Tue - 07/01/25

**Title:

      Pseudo-Complex Gravity as a Geometric Resolution of the Black Hole Information Paradox**  - **Authors:** Fridolin Weberand Peter O. Hess, Cesar A. Zen Vasconcellos  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We investigate the black hole information paradox in the setting of pseudo-complex gravity, a covariant geometric extension of general relativity that introduces a minimal length scale by deforming the spacetime manifold. In this framework, curvature invariants stay finite, and the classical singularity is geometrically regularized via a smooth core. We show that the correction term B/(6r**4) alters the Schwarzschild metric, generating the regularized geometry above, yielding a finite Hawking temperature, and inducing subleading corrections to the Bekenstein-Hawking entropy. Crucially, we demonstrate that the pseudo-complex geometric structure obstructs a clean factorization of the Hilbert space into interior and exterior regions, thereby removing the key assumption behind the standard derivation of the paradox. This structural reinterpretation of entanglement flow offers a new geometric route to unitarity preservation and information recovery. We examine the resulting effects on evaporation dynamics, entropy flow, and thermodynamic behavior. Our predictions are compared with those of generalized uncertainty principles (GUP), loop quantum gravity (LQG), and island-based models, and are summarized in a comparative table. Observable signatures-such as shifts in quasi-normal mode frequencies and the appearance of gravitational wave echoes from the regularized core-suggest that pseudo-complex gravity is a testable, covariant approach to resolving the paradox without invoking firewalls, holography, or exotic quantum states.

There is no new related paper today

Mon - 06/30/25

**Title:

      Pseudo-Complex Gravity as a Geometric Resolution of the Black Hole Information Paradox**  - **Authors:** Fridolin Weberand Peter O. Hess, Cesar A. Zen Vasconcellos  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We investigate the black hole information paradox in the setting of pseudo-complex gravity, a covariant geometric extension of general relativity that introduces a minimal length scale by deforming the spacetime manifold. In this framework, curvature invariants stay finite, and the classical singularity is geometrically regularized via a smooth core. We show that the correction term B/(6r**4) alters the Schwarzschild metric, generating the regularized geometry above, yielding a finite Hawking temperature, and inducing subleading corrections to the Bekenstein-Hawking entropy. Crucially, we demonstrate that the pseudo-complex geometric structure obstructs a clean factorization of the Hilbert space into interior and exterior regions, thereby removing the key assumption behind the standard derivation of the paradox. This structural reinterpretation of entanglement flow offers a new geometric route to unitarity preservation and information recovery. We examine the resulting effects on evaporation dynamics, entropy flow, and thermodynamic behavior. Our predictions are compared with those of generalized uncertainty principles (GUP), loop quantum gravity (LQG), and island-based models, and are summarized in a comparative table. Observable signatures-such as shifts in quasi-normal mode frequencies and the appearance of gravitational wave echoes from the regularized core-suggest that pseudo-complex gravity is a testable, covariant approach to resolving the paradox without invoking firewalls, holography, or exotic quantum states.

There is no new related paper today

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