  The gaussian damping factor (g.d.f.) and the new interaction vertex with the
symplectic tensor are the characteristic properties of the N-point
scalar-vector scattering amplitudes of the p-p' (p < p') open string system
which realizes noncommutative geometry. The g.d.f. is here interpreted as a
form factor of the Dp-brane by noncommutative U(1) current. Observing that the
g.d.f. is in fact equal to the Fourier transform of the noncommutative
projector soliton introduced by Gopakumar, Minwalla and Strominger, we further
identify the Dp-brane in the zero slope limit with the noncommutative soliton
state. It is shown that the g.d.f. depends only on the total momentum of N-2
incoming/outgoing photons in the zero slope limit. In the description of the
low-energy effective action (LEEA) proposed before, this is shown to follow
from the delta function propagator and the form of the initial/final wave
functions in the soliton sector which resides in x^{m} m= p+1, ...p' dependent
part of the scalar field \Phi(x^\mu, x^m). The three and four point amplitudes
computed from LEEA agree with string calculation. We discuss related issues
which are resummation/lifting of infinite degeneracy and conservation of
momentum transverse to the Dp-brane.
