Tunneling D0-branes
  In the D0-D4-brane system, D0-branes do not tunnel. Instead, they form bound states with the D4-brane, whose ground states are exact. However, the D0-brane quantum mechanics contains a BPS instanton. To what does this solution correspond? We find that such a tunneling solution provides non-perturbative corrections to the Berry phase connection for the first-excited states as the D4-branes are moved adiabatically. We compute this connection for the first four excited states, and show that it gives an emergent SO(5) connection described previously by Tchrakian. 
Chris Pedder