A novel PBH production mechanism from non-Abelian gauge fields during inflation

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Main Authors: Dimastrogiovanni, Ema, Fasiello, Matteo, Papageorgiou, Alexandros
Format: Preprint
Published: 2024
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author Dimastrogiovanni, Ema
Fasiello, Matteo
Papageorgiou, Alexandros
author_facet Dimastrogiovanni, Ema
Fasiello, Matteo
Papageorgiou, Alexandros
contents We consider the case of axion-like particles (ALPs) during inflation. When coupled to a non-Abelian gauge sector via a Chern-Simons term, ALPs support an intriguing, testable, phenomenology with very distinctive features including chiral primordial gravitational waves. For sufficiently small values of the gauge vev and coupling, scalar perturbations in the gauge sector exhibit a known instability. We harness the power of such instability for primordial black hole (PBH) generation. In the case of an axion-inflaton, one is dynamically driven into a strong-backreaction regime that crosses the instability band thereby sourcing a peaked scalar spectrum leading to PBH production and the related scalar-induced gravitational waves. Remarkably, this dynamics is largely insensitive to the initial conditions and the shape of the potential, highlighting the universal nature of the sourcing mechanism. In the case of spectator ALPs one can identify the parameter space that sets off the strong backreaction regime and the ensuing features. We show that spectator ALP models may also access the scalar instability region without triggering strong backreaction.
format Preprint
id arxiv_https___arxiv_org_abs_2403_13581
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A novel PBH production mechanism from non-Abelian gauge fields during inflation
Dimastrogiovanni, Ema
Fasiello, Matteo
Papageorgiou, Alexandros
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
We consider the case of axion-like particles (ALPs) during inflation. When coupled to a non-Abelian gauge sector via a Chern-Simons term, ALPs support an intriguing, testable, phenomenology with very distinctive features including chiral primordial gravitational waves. For sufficiently small values of the gauge vev and coupling, scalar perturbations in the gauge sector exhibit a known instability. We harness the power of such instability for primordial black hole (PBH) generation. In the case of an axion-inflaton, one is dynamically driven into a strong-backreaction regime that crosses the instability band thereby sourcing a peaked scalar spectrum leading to PBH production and the related scalar-induced gravitational waves. Remarkably, this dynamics is largely insensitive to the initial conditions and the shape of the potential, highlighting the universal nature of the sourcing mechanism. In the case of spectator ALPs one can identify the parameter space that sets off the strong backreaction regime and the ensuing features. We show that spectator ALP models may also access the scalar instability region without triggering strong backreaction.
title A novel PBH production mechanism from non-Abelian gauge fields during inflation
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2403.13581