Barrow Cosmology and Big-Bang Nucleosynthesis
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| Format: | Preprint |
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2024
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| author | Sheykhi, Ahmad Sooraki, Ava Shahbazi |
| author_facet | Sheykhi, Ahmad Sooraki, Ava Shahbazi |
| contents | Using thermodynamics-gravity conjecture, we present the formal derivation of the modified Friedmann equations inspired by the Barrow entropy, $S\sim A ^{1+δ/2}$, where $0\leqδ\leq 1$ is the Barrow exponent and $A$ is the horizon area. We then constrain the exponent $δ$ by using Big-Bang Nucleosynthesis (BBN) observational data. In order to impose the upper bound on the Barrow exponent $δ$, we set the observational bound on $\left| \frac{δT_f} {T_f }\right|$. We find out that the Barrow parameter $δ$ should be around $ δ\simeq 0.01$ in order not to spoil the BBN era. Next we derive the bound on the Barrow exponent $δ$ in a different approach in which we analyze the effects of Barrow cosmology on the primordial abundances of light elements i.e. Helium $_{}^{4}\textit{He}$, Deuterium $D$ and Lithium $_{}^{7}\textit{Li}$. We observe that the deviation from standard Bekenstein-Hawking expression is small as expected. Additionally we present the relation between cosmic time $t$ and temperature $T$ in the context of modified Barrow cosmology. We confirm that the temperature of the early universe increases as the Barrow exponent $δ$ (fractal structure of the horizon) increases, too. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2411_06075 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Barrow Cosmology and Big-Bang Nucleosynthesis Sheykhi, Ahmad Sooraki, Ava Shahbazi General Relativity and Quantum Cosmology High Energy Physics - Theory Using thermodynamics-gravity conjecture, we present the formal derivation of the modified Friedmann equations inspired by the Barrow entropy, $S\sim A ^{1+δ/2}$, where $0\leqδ\leq 1$ is the Barrow exponent and $A$ is the horizon area. We then constrain the exponent $δ$ by using Big-Bang Nucleosynthesis (BBN) observational data. In order to impose the upper bound on the Barrow exponent $δ$, we set the observational bound on $\left| \frac{δT_f} {T_f }\right|$. We find out that the Barrow parameter $δ$ should be around $ δ\simeq 0.01$ in order not to spoil the BBN era. Next we derive the bound on the Barrow exponent $δ$ in a different approach in which we analyze the effects of Barrow cosmology on the primordial abundances of light elements i.e. Helium $_{}^{4}\textit{He}$, Deuterium $D$ and Lithium $_{}^{7}\textit{Li}$. We observe that the deviation from standard Bekenstein-Hawking expression is small as expected. Additionally we present the relation between cosmic time $t$ and temperature $T$ in the context of modified Barrow cosmology. We confirm that the temperature of the early universe increases as the Barrow exponent $δ$ (fractal structure of the horizon) increases, too. |
| title | Barrow Cosmology and Big-Bang Nucleosynthesis |
| topic | General Relativity and Quantum Cosmology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2411.06075 |