Lepton number asymmetries and the lower bound on the reheating temperature

Abstract

We show that the reheating temperature of a matter-domination era in the early universe can be pushed down to the neutrino decoupling temperature at around $2\mathrm{MeV}$ if the reheating takes place through non-hadronic decays of the dominant matter and neutrino-antineutrino asymmetries are still large enough, $|L|\gtrsim \mathcal{O}(10^{-2})$ (depending on the neutrino flavor) at the end of reheating.

8 pages, 4 figures: new figures added, minor changes in conclusions, matches the version published in JCAP