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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2405.00090 |
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| _version_ | 1866908373108129792 |
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| author | Müürsepp, Kristjan Nardi, Enrico Smarra, Clemente |
| author_facet | Müürsepp, Kristjan Nardi, Enrico Smarra, Clemente |
| contents | We propose a mechanism in which the current acceleration of cosmic expansion is driven by continuous creation of energy density $ρ_b$ for a certain field $φ_b$. We accordingly modify Einstein equation, derive modified Friedmann equations and analyze the regimes in which cosmic acceleration occurs. The creation process requires $ρ_b\neq 0$ as initial condition, which we enforce by identifying $φ_b$ with the axion of a hidden gauge group that confined in recent cosmological times, leading to a level crossing between $φ_b$ and the QCD axion, which is assumed to comprise dark matter. The conversion of a small fraction of QCD axions into $φ_b$ shortly before matter-dark energy equality generates the initial $ρ_b$ needed to trigger the creation process and offers a solution to the coincidence puzzle. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_00090 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Accelerated cosmic expansion, mass creation, and the QCD axion Müürsepp, Kristjan Nardi, Enrico Smarra, Clemente High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics We propose a mechanism in which the current acceleration of cosmic expansion is driven by continuous creation of energy density $ρ_b$ for a certain field $φ_b$. We accordingly modify Einstein equation, derive modified Friedmann equations and analyze the regimes in which cosmic acceleration occurs. The creation process requires $ρ_b\neq 0$ as initial condition, which we enforce by identifying $φ_b$ with the axion of a hidden gauge group that confined in recent cosmological times, leading to a level crossing between $φ_b$ and the QCD axion, which is assumed to comprise dark matter. The conversion of a small fraction of QCD axions into $φ_b$ shortly before matter-dark energy equality generates the initial $ρ_b$ needed to trigger the creation process and offers a solution to the coincidence puzzle. |
| title | Accelerated cosmic expansion, mass creation, and the QCD axion |
| topic | High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2405.00090 |