  In a plane-wave matrix model we discuss a two-body scattering of gravitons in
the SO(3) symmetric space. In this case the graviton solutions are point-like
in contrast to the scattering in the SO(6) symmetric space where spherical
membranes are interpreted as gravitons. We concentrate on a configuration in
the 1-2 plane where a graviton rotates with a constant radius and the other one
elliptically rotates. Then the one-loop effective action is computed by using
the background field method. As the result, we obtain the 1/r^7-type
interaction potential, which strongly suggests that the scattering in the
matrix model would be closely related to that in the light-front
eleven-dimensional supergravity.
