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arXiv · 2510.19629

Beyond Standard Model equation of state and primordial black holes

Xavier Pritchard·Matthew Starbuck·Wingfung Leung
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Abstract

The Standard Model of particle physics successfully describes all known fundamental particles and their interactions; however, it leaves several unanswered questions. Theories beyond the Standard Model typically introduce new particles and symmetries to address these issues. In the early universe, when such particles become non-relativistic, or the symmetries are broken, there are associated reductions in the equation of state of the primordial plasma. These reductions lead to an exponential enhancement in the formation rate of primordial black holes. In this paper, we calculate the equation of state for several supersymmetric and composite Higgs models, which naturally predict a large number of additional degrees of freedom. Using these equations of state, we compute some example primordial black hole abundances, which we find can be enhanced by up to 20 orders of magnitude.

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Xavier Pritchard, Matthew Starbuck, Wingfung Leung. 2025-10-22. Beyond Standard Model equation of state and primordial black holes. https://arxiv.org/abs/2510.19629

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