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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie

GR 13: Quantum Gravity and Quantum Cosmology I

GR 13.2: Talk

Thursday, March 19, 2026, 14:00–14:15, KH 02.012

Gravitational collapse in effective loop quantum gravity and the formation of shell-crossing singularities — Francesco Fazzini¹, Kristina Giesel¹, Hongguang Liu², and •Eric Rullit¹ — ¹Institute for Quantum Gravity, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany — ²Institute for Theoretical Sciences, Westlake University, Hangzhou, China

In this talk the investigation of the gravitational dust collapse within the framework of effective loop quantum gravity will be addressed, with a special focus on the properties and the formation of shell-crossing singularities in these models. The specific effective model that will be discussed in this talk is based on a cosmological Hamiltonian derived from full LQG by Dapor and Liegener using coherent state techniques, which governs the FLRW-type time evolution of each radial shell in the collapsing dust sphere. This model is characterized by an asymmetric bounce as its central feature where the classical singularity is resolved due to leading-order quantum corrections encoded in the effective description. The investigation of the resulting effective dynamics will be presented in detail and differences and similarities compared to other existing models will be discussed. In a broader context, the question of the existence of shell-crossing singularities is investigated beyond the specific model, including also non-bouncing scenarios such as regular black hole models of Bardeen and Hayward.

Keywords: Loop quantum gravity; Effective models; Gravitational collapse; Shell-crossing singularities