Born-Infeld Dynamics in Uniform Electric Field

We investigate various properties of classical configurations of the Born-Infeld theory in a uniform electric field. This system is involved with dynamics of (F,Dp) bound states, which are bound states of fundamental strings and Dp-branes. The uniform electric field can be treated as a constraint on the asymptotic behavior of the fields on the brane. BPS configurations in this theory correspond to fundamental strings attached to the (F,Dp) bound state, and are found to be stable due to force balance. Fluctuations around these stable configurations are subject to appropriate Dirichlet and Neumann boundary conditions which are identical with the ones deduced from the ordinary worldsheet description of the attached string. Additionally, non-BPS solutions are studied and related physics are discussed.Comment: 16 pages, 2 figures ; references adde

Generalized Supersymetric Boundary State

Following our previous paper (hep-th/9909027), we generalize a supersymmetric boundary state so that arbitrary configuration of the gauge field coupled to the boundary of the worldsheet is incorpolated. This generalized boundary state is BRST invariant and satisfy the non-linear boundary conditions with non-constant gauge field strength. This boundary state contains divergence which is identical with the loop divergence in a superstring sigma model. Hence vanishing of the beta function in the superstring sigma model corresponds to a well-defined boundary state with no divergence. The coupling of a single closed superstring massless mode with multiple open string massless modes is encoded in the boundary state, and we confirm that derivative correction to the D-brane action in this sector vanishes up to the first non-trivial order O(alpha'(derivative)^2). Combining T-dualities, we incorpolate also general configurations of the scalar fields on the D-brane, and construct boundary states representing branes stuck to another D-brane, with use of BIon configuration.Comment: 27 pages, LaTeX, 1 eps figure, typos correcte

Branes Ending On Branes In A Tachyon Model

In a tachyon model proposed by Minahan and Zwiebach and derived in the boundary string field theory, we construct various new solutions which correspond to nontrivial brane configurations in string theory. Our solutions include Dp-D(p-2) bound states, (F, Dp) bound states, string junctions, D(p-2)-branes ending on a Dp-brane, D(p-2)-branes suspended between parallel Dp-branes and their non-commutative generalizations. We find the Bogomol'nyi bounds and the BPS equations for some of our solutions, and check the physical consistency of our solutions with the D-brane picture by looking at the distributions of their energies and RR-charges in space. We also give conjectures for a few other brane configurations.Comment: 19 pages, LaTeX, minor corrections and references adde