  Using string scattering amplitudes of open bosonic string on a single
$D$-brane, we construct a local field theoretical action for tachyon fields.
Cubic local interactions between various particles, belonging to the particle
spectrum of string may be directly followed from three-string scattering
amplitude. These cubic local interactions may generate perturbative non-local
four-particle interactions, which may contribute to four-string scattering
amplitude. It was observed that tachyon field in open bosonic string theory
must be represented by a complex field in order to reproduce the Veneziano
amplitude, describing four-tachyon scattering. The Veneziano amplitude,
expanded in terms of $s$-channel poles was compared with the four-tachyon
scattering amplitudes in $s$-channel generated perturbatively and it was found
that a quartic potential term is needed in the local field theoretical action,
which describes open string theory effectively in the low energy regime. With
this quartic term, the tachyon potential has a stable minimum point and the
tachyon field may condensate. As a result, both tachyon and gauge fields become
massive at Planck scale and completely disappear from the low energy particle
spectrum.
