Schnabl's solution and boundary states in open string field theory

We discuss that Schnabl's Solution is an off-shell extension of the boundary state describing a D-brane in the closed string sector. It gives the physical meaning of the gauge-invariant overlaps for the solution in our previous paper and supports Ellwood's recent proposal in the operator formalism. (C) 2008 Elsevier B.V. All rights reserved.