Abstract

Late-time entropy productions due to the decay of non-relativistic massive particles influences the standard scenario. If the matter-dominated epoch continues so long that the radiation-domination can not be realized completely at a cosmic time t[〜!_] 1 sec, the universe would fail to produce the light elements. We find that the reheating temperature T_R should be greater than 0.5 MeV in order to agree with observations.