  We study the propagation of gravitons within 5-D supersymmetric braneworld
models with a bulk scalar field. The setup considered here consists of a 5-D
bulk spacetime bounded by two 4-D branes localized at the fixed points of an
$S^1/Z_2$ orbifold. There is a scalar field $\phi$ in the bulk which, provided
a superpotential $W(\phi)$, determines the warped geometry of the 5-D
spacetime. This type of scenario is common in string theory, where the bulk
scalar field $\phi$ is related to the volume of small compact extra dimensions.
We show that, after the moduli are stabilized by supersymmetry breaking terms
localized on the branes, the only relevant degrees of freedom in the bulk
consist of a 5-D massive spectrum of gravitons. Then we analyze the
gravitational interaction between massive bodies localized at the positive
tension brane mediated by these bulk gravitons. It is shown that the Newtonian
potential describing this interaction picks up a non-trivial contribution at
short distances that depends on the shape of the superpotential $W(\phi)$. We
compute this contribution for dilatonic braneworld scenarios $W(\phi) =
e^{\alpha \phi}$ (where $\alpha$ is a constant) and discuss the particular case
of 5-D Heterotic M-theory: It is argued that a specific footprint at micron
scales could be observable in the near future.
