Brane Death and Dynamics From the Born-Infeld Action

We use the abelian Born-Infeld action for the worldvolume gauge field and transverse displacement scalars to explore new aspects of D-brane structure and dynamics. We study several classic gauge field configurations, including point charges in any worldvolume dimension and vortices in two worldvolume dimensions, and show that, with an appropriate excitation of the transverse coordinate field, they are BPS-saturated solutions. The Coulomb point charge solutions turn out to represent, with considerable fidelity, fundamental strings attached to the brane (their magnetic counterparts describe D1-branes attached to D3-branes). We also study dynamic issues. First, we show that S-matrix for small excitations propagating on the point charge solution is consistent with (and gives further illuminating information about) Polchinski’s effective open string boundary condition. Second, we show that the worldvolume action has Euclidean bounce solutions which describe the decay of widely-separated brane-antibrane pairs via the nucleation and subsequent expansion of a throat joining the brane and the antibrane.