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Main Authors: Boos, Jens, Gündoğdu, Arif Kağan, Hartenfels, Marek
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.30340
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author Boos, Jens
Gündoğdu, Arif Kağan
Hartenfels, Marek
author_facet Boos, Jens
Gündoğdu, Arif Kağan
Hartenfels, Marek
contents Non-singular gravitational theories are expected to be relevant in the early universe. In this paper, we derive a set of effective Friedmann equations describing the dynamics of matter shells in the presence of a gravitational regulator $\ell$. We find that such a regulator induces a primordial black hole mass gap such that below a certain mass $M_\text{gap}(\ell, R_H)$ no black holes can form. The order of magnitude of this mass gap is set by the regulator $\sim c^2\ell/G$, with subleading dependence on the horizon radius at time of formation $R_H$. Finally, we show that over a wide range of equation of state parameters $ω= 0 \dots 1/3$, the mass gap implies a Carr criterion of the form $δ_H > 2G M_\text{gap}/R_H - 1$. If the horizon size is of the same order of the regulator, $R_H \sim \ell$, this new criterion is stronger than the traditional Carr criterion for primordial black hole formation. This connects the primordial black hole abundance directly to the presence of gravitational regulators.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30340
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Carr criterion and mass gaps in non-singular primordial black hole formation
Boos, Jens
Gündoğdu, Arif Kağan
Hartenfels, Marek
General Relativity and Quantum Cosmology
Non-singular gravitational theories are expected to be relevant in the early universe. In this paper, we derive a set of effective Friedmann equations describing the dynamics of matter shells in the presence of a gravitational regulator $\ell$. We find that such a regulator induces a primordial black hole mass gap such that below a certain mass $M_\text{gap}(\ell, R_H)$ no black holes can form. The order of magnitude of this mass gap is set by the regulator $\sim c^2\ell/G$, with subleading dependence on the horizon radius at time of formation $R_H$. Finally, we show that over a wide range of equation of state parameters $ω= 0 \dots 1/3$, the mass gap implies a Carr criterion of the form $δ_H > 2G M_\text{gap}/R_H - 1$. If the horizon size is of the same order of the regulator, $R_H \sim \ell$, this new criterion is stronger than the traditional Carr criterion for primordial black hole formation. This connects the primordial black hole abundance directly to the presence of gravitational regulators.
title Carr criterion and mass gaps in non-singular primordial black hole formation
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2605.30340