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| Natura: | Preprint |
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2026
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| Accesso online: | https://arxiv.org/abs/2604.27954 |
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| _version_ | 1866909021158506496 |
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| author | Pérez-Poyatos, José María |
| author_facet | Pérez-Poyatos, José María |
| contents | In this work, we extend the standard pre-inflationary misalignment mechanism for axion-like particles (ALPs) by introducing a pre-oscillatory phase with constant equation of state $ω_ϕ\in[-1,1]$, generated by a tracking potential. During the radiation-dominated era, the potential undergoes a rapid transition to the conventional cosine potential. The resulting change in the potential energy across the transition can drive the ALP into a kinetic misalignment phase ($ω_ϕ=1$) prior to the onset of oscillations. Motivated by persistent cosmological tensions, such as those in $H_0$ and $S_8$, we also investigate an ALP coupling to a dark radiation sector (DR), allowing for its decay. Using a Bayesian analysis, we constrain the ALP parameter space with current cosmological data. Our analysis shows that ALP-induced DR does not resolve the existing tensions. Instead, the data place robust constraints on the model, favoring negative values of $ω_ϕ$ and constraining the symmetry-breaking scale to $f_ϕ\in[80,1.5\times10^{10}]~\mathrm{TeV}$, corresponding to ALP masses in the range $m_ϕ\in[10^{-20},10^{-2}]~\mathrm{eV}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_27954 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Axion dark matter from extended misalignment with a constant-$ω_ϕ$ pre-oscillatory phase and dark radiation Pérez-Poyatos, José María Cosmology and Nongalactic Astrophysics In this work, we extend the standard pre-inflationary misalignment mechanism for axion-like particles (ALPs) by introducing a pre-oscillatory phase with constant equation of state $ω_ϕ\in[-1,1]$, generated by a tracking potential. During the radiation-dominated era, the potential undergoes a rapid transition to the conventional cosine potential. The resulting change in the potential energy across the transition can drive the ALP into a kinetic misalignment phase ($ω_ϕ=1$) prior to the onset of oscillations. Motivated by persistent cosmological tensions, such as those in $H_0$ and $S_8$, we also investigate an ALP coupling to a dark radiation sector (DR), allowing for its decay. Using a Bayesian analysis, we constrain the ALP parameter space with current cosmological data. Our analysis shows that ALP-induced DR does not resolve the existing tensions. Instead, the data place robust constraints on the model, favoring negative values of $ω_ϕ$ and constraining the symmetry-breaking scale to $f_ϕ\in[80,1.5\times10^{10}]~\mathrm{TeV}$, corresponding to ALP masses in the range $m_ϕ\in[10^{-20},10^{-2}]~\mathrm{eV}$. |
| title | Axion dark matter from extended misalignment with a constant-$ω_ϕ$ pre-oscillatory phase and dark radiation |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2604.27954 |