Lepton number asymmetries and the lower bound on the reheating
  temperature
  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 $2 \ {\rm MeV}$ 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.
