Carr criterion and mass gaps in non-singular primordial black hole formation
Abstract
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 . We find that such a regulator induces a primordial black hole mass gap such that below a certain mass no black holes can form. The order of magnitude of this mass gap is set by the regulator , with subleading dependence on the horizon radius at time of formation . Finally, we show that over a wide range of equation of state parameters , the mass gap implies a Carr criterion of the form . If the horizon size is of the same order of the regulator, , 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.
Comments: 8 pages, 3 figures, comments welcome!
Cite
@article{arxiv.2605.30340,
title = {Carr criterion and mass gaps in non-singular primordial black hole formation},
author = {Jens Boos and Arif Kağan Gündoğdu and Marek Hartenfels},
journal= {arXiv preprint arXiv:2605.30340},
year = {2026}
}