Big Bang Nucleosynthesis constraints on Barrow entropy

Understand

We use Big Bang Nucleosynthesis (BBN) data in order to impose constraints on the exponent of Barrow entropy.

• The latter is an extended entropy relation arising from the incorporation of quantum-gravitational effects on the black-hole structure, parameterized effectively by the new parameter $\Delta$.
• When considered in a cosmological framework and under the light of the gravity-thermodynamics conjecture, Barrow entropy leads to modified cosmological scenarios whose Friedmann equations contain extra terms.
• We perform a detailed analysis of the BBN era and we calculate the deviation of the freeze-out temperature comparing to the result of standard cosmology.