  The interaction between a parallel brane-antibrane and brane-antibrane is
investigated by regarding the brane-antibrane pair as a kink or anti-kink type
tachyon condensed state. As the kink-type tachyon condensed state is known as a
non-BPS brane we expand the Lagrangian of tachyon effective field theory to the
quadratic order in the off-diagonal fluctuation and then use the zeta-function
regularization and Schwinger perturbative formula to evaluate the interaction
within a kink-kink or a kink-antikink.
  The results show that while the kink and kink has repulsive force the kink
and anti-kink has attractive force and may annihilate by each others. We
therefore evaluate the free energy at finite temperature and determine the
critical temperature above which the stable state of kink-antikink system may
be found.
