Dark matter relic abundance from a critical-density instability
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arXiv
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| Format: | Preprint |
| Publié: |
2026
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| _version_ | 1866918380584304640 |
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| author | Zouhair, Hindi |
| author_facet | Zouhair, Hindi |
| contents | We study a nonstandard dark-matter thermal history in which strong self-interactions give rise to collective many-body effects at high number density, as in strongly interacting quantum media. At early times, dark matter occupies a correlated phase in which its coupling to a light mediator is dynamically screened, suppressing annihilation far below the perturbative rate. As the Universe expands and the number density decreases, this screened phase becomes unstable at a critical density n_c, triggering a rapid, far-from-equilibrium annihilation episode. We show that this annihilation burst fixes the final relic abundance, which is governed primarily by n_c rather than by the microscopic annihilation coupling. Using a minimal effective parametrization, we solve the resulting modified Boltzmann evolution and map the viable parameter space. For TeV-scale dark matter and sub-GeV mediators, we find relic abundances consistent with observations together with self-interaction cross sections relevant for small-scale structure, realizing a consistent and predictive nonstandard thermal history. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_08749 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Dark matter relic abundance from a critical-density instability Zouhair, Hindi High Energy Physics - Phenomenology We study a nonstandard dark-matter thermal history in which strong self-interactions give rise to collective many-body effects at high number density, as in strongly interacting quantum media. At early times, dark matter occupies a correlated phase in which its coupling to a light mediator is dynamically screened, suppressing annihilation far below the perturbative rate. As the Universe expands and the number density decreases, this screened phase becomes unstable at a critical density n_c, triggering a rapid, far-from-equilibrium annihilation episode. We show that this annihilation burst fixes the final relic abundance, which is governed primarily by n_c rather than by the microscopic annihilation coupling. Using a minimal effective parametrization, we solve the resulting modified Boltzmann evolution and map the viable parameter space. For TeV-scale dark matter and sub-GeV mediators, we find relic abundances consistent with observations together with self-interaction cross sections relevant for small-scale structure, realizing a consistent and predictive nonstandard thermal history. |
| title | Dark matter relic abundance from a critical-density instability |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2603.08749 |