Primordial black holes from the ultraslow-roll phase in the inflaton--curvaton mixed field inflation
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| Format: | Preprint |
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2025
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| _version_ | 1866915162679672832 |
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| author | Su, Bing-Yu Li, Nan Feng, Lei |
| author_facet | Su, Bing-Yu Li, Nan Feng, Lei |
| contents | Primordial black holes (PBHs) are a promising candidate for dark matter, as they can form in the very early universe without invoking new particle physics. This work explores PBH formation within a curvaton scenario featuring an ultraslow-roll (USR) phase. An inflaton--curvaton mixed field model is presented, where the inflaton drives early inflation and then transits into the USR phase, amplifying the small-scale curvature perturbation. During inflation, the curvaton generates entropy perturbation, which later converts into curvature perturbation after the curvaton decays in the radiation-dominated era. Using the $δN$ formalism, we compute the power spectrum of the total primordial curvature perturbation and analyze the relevant non-Gaussianity. Our results show that adding a curvaton field not only has a significant impact on primordial non-Gaussianity, but also introduces more complex inflationary dynamics, even saving the inflaton potentials that generate too low scalar spectral indices. Our model can produce PBHs with mass around $10^{-14}\,M_\odot$ that account for all dark matter, while remaining consistent with current observational constraints. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_14323 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Primordial black holes from the ultraslow-roll phase in the inflaton--curvaton mixed field inflation Su, Bing-Yu Li, Nan Feng, Lei Cosmology and Nongalactic Astrophysics Primordial black holes (PBHs) are a promising candidate for dark matter, as they can form in the very early universe without invoking new particle physics. This work explores PBH formation within a curvaton scenario featuring an ultraslow-roll (USR) phase. An inflaton--curvaton mixed field model is presented, where the inflaton drives early inflation and then transits into the USR phase, amplifying the small-scale curvature perturbation. During inflation, the curvaton generates entropy perturbation, which later converts into curvature perturbation after the curvaton decays in the radiation-dominated era. Using the $δN$ formalism, we compute the power spectrum of the total primordial curvature perturbation and analyze the relevant non-Gaussianity. Our results show that adding a curvaton field not only has a significant impact on primordial non-Gaussianity, but also introduces more complex inflationary dynamics, even saving the inflaton potentials that generate too low scalar spectral indices. Our model can produce PBHs with mass around $10^{-14}\,M_\odot$ that account for all dark matter, while remaining consistent with current observational constraints. |
| title | Primordial black holes from the ultraslow-roll phase in the inflaton--curvaton mixed field inflation |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2502.14323 |