BRST Invariant Mixed String Vertex for the Bosonic String.

摘要

We construct a BRST invariant (N+M)-string vertex including both open and closed string states. When we saturate it with N open string and M closed string physical states it reproduces their corresponding scattering amplitude. As a particular case we obtain BRST invariant vertex for the open-closed string transition. (ERA citation 14:002226)