  We present an analytic method based on the Hadamard-WKB expansion to
calculate the self-force for a particle with scalar charge that undergoes
radial infall in a Schwarzschild spacetime after being held at rest until a
time t = 0. Our result is valid in the case of short duration from the start.
It is possible to use the Hadamard-WKB expansion in this case because the value
of the integral of the retarded Green's function over the particle's entire
past trajectory can be expressed in terms of two integrals over the time period
that the particle has been falling. This analytic result is expected to be
useful as a check for numerical prescriptions including those involving mode
sum regularization and for any other analytical approximations to self-force
calculations.
