On Multibrane Solutions in Open String Field Theory

Existence of open string field theory solutions describing configurations of multiple space-filling D-branes has been a subject of numerous speculations for quite some time. In this talk we present some new results giving further support to these ideas.Comment: 8 pages. Contribution to the proceedings of the 3rd International Conference on String Field Theory and Related Aspects (SFT 2010), Kyoto, Japan, 18-22 Oct 201

No-Ghost Theorem for Neveu-Schwarz String in 0-Picture

The no-ghost theorem for Neveu-Schwarz string is directly proved in 0-picture. The one-to-one correspondence between physical states in 0-picture and those in the conventional (-1)-picture are confirmed. It is shown that a non-trivial metric consistent with the BRST cohomology is needed to define a positive semi-definite norm in the physical Hilbert space. As a by-product, we find a new inverse picture changing operator, which is non-covariant but has non-singular operator product with itself. A possibility to construct a new gauge invariant superstring field theory is discussed.Comment: 18 pages, v2:typos corrected, v3:published version, v4:typos correcte