  We discuss long-distance, low-velocity interaction potentials for processes
involving longitudinally boosted M5-brane (corresponding in type IIA theory
language to the 1/4 supersymmetric bound state of 4-brane and 0-brane). We
consider the following scattering configurations: (a) D=11 graviton off
longitudinal M5-brane, or, equivalently, 0-branes off marginal 4+0 bound state;
(b) M2-brane off longitudinal M5-brane, or a non-marginal 2+0 bound state off
marginal 4+0 bound state; (c) two parallel longitudinal M5-branes, or two 4+0
marginal bound states. We demonstrate the equivalence between the classical
closed string theory (supergravity) and M(atrix) model (one-loop super
Yang-Mills) results for the leading terms in the interaction potentials. The
supergravity results are obtained using a generalisation of the classical probe
method which allows one to treat bound states of D-branes as probes by
introducing non-trivial world-volume gauge field backgrounds.
