Constraining Tsallis Corrections to Photon Reheating from Electron-Positron Annihilation
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arXiv
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| Formato: | Preprint |
| Publicado: |
2026
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| _version_ | 1866918482603409408 |
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| author | Gonzalez, Matias P. |
| author_facet | Gonzalez, Matias P. |
| contents | In this work we generalize the entropy transfer from electron-positron annihilation to photons in the early Universe. The generalization is implemented within the Tsallis formalism by using generalized distribution functions derived from Curado-Tsallis constraints. Through this deformation, the entropy density of the electromagnetic sector is modified, while the photon component is kept extensive. Therefore, the nonextensive correction is introduced only in the $e^-e^+$ pairs. This affects the entropic degrees of freedom before electron-positron annihilation and consequently modifies the temperature ratio $T_ν/T_γ$. The resulting correction is then mapped into the effective number of relativistic species, $N_{\rm eff}$. Finally, by performing a combined $χ^2$ analysis using CMB$+$BAO and BBN data, we obtain the $2σ$ bound $|q-1|\leq 1.3\times10^{-2}$ for the nonextensive parameter. This result implies that any departure or correction from Boltzmann-Gibbs extensivity must remain small during the MeV era. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_03223 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Constraining Tsallis Corrections to Photon Reheating from Electron-Positron Annihilation Gonzalez, Matias P. High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics Statistical Mechanics In this work we generalize the entropy transfer from electron-positron annihilation to photons in the early Universe. The generalization is implemented within the Tsallis formalism by using generalized distribution functions derived from Curado-Tsallis constraints. Through this deformation, the entropy density of the electromagnetic sector is modified, while the photon component is kept extensive. Therefore, the nonextensive correction is introduced only in the $e^-e^+$ pairs. This affects the entropic degrees of freedom before electron-positron annihilation and consequently modifies the temperature ratio $T_ν/T_γ$. The resulting correction is then mapped into the effective number of relativistic species, $N_{\rm eff}$. Finally, by performing a combined $χ^2$ analysis using CMB$+$BAO and BBN data, we obtain the $2σ$ bound $|q-1|\leq 1.3\times10^{-2}$ for the nonextensive parameter. This result implies that any departure or correction from Boltzmann-Gibbs extensivity must remain small during the MeV era. |
| title | Constraining Tsallis Corrections to Photon Reheating from Electron-Positron Annihilation |
| topic | High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics Statistical Mechanics |
| url | https://arxiv.org/abs/2605.03223 |