  Pair creation in a uniform classical electromagnetic field (Schwinger
mechanism) is studied focusing on the time evolution of the distribution of
created particles. The time evolution of the distribution in time-dependent
fields is also presented as well as effects of back reaction. Motivated by the
Glasma flux tube, which may be formed at the initial stage of heavy-ion
collisions, we investigate effects of a magnetic field parallel to an electric
field, and find that the magnetic field makes the evolution of a fermion system
faster.
