D-branes and Closed String Field Theory

TL;DR

This paper constructs BRST invariant solitonic states in closed bosonic string field theory using boundary states for D-branes, reproducing cylinder amplitudes and exploring D-brane excitations.

Contribution

It generalizes previous noncritical case constructions to the OSp invariant string field theory, introducing D-brane and ghost D-brane states.

Findings

Reproduces cylinder amplitudes for D-branes

Constructs states with even numbers of D-branes or ghost D-branes

Demonstrates BRST invariance of solitonic states

Abstract

We construct BRST invariant solitonic states in the OSp invariant string field theory for closed bosonic strings. Our construction is a generalization of the one given in the noncritical case. These states are made by using the boundary states for D-branes, and can be regarded as states in which D-branes or ghost D-branes are excited. We calculate the vacuum amplitude in the presence of solitons perturbatively and show that the cylinder amplitude for the D-brane is reproduced. The results imply that these are states with even number of D-branes or ghost D-branes.