Extension of Boundary String Field Theory on Disc and RP2 Worldsheet   Geometries
  We present a construction of open-closed string field theory based on disc and RP2 geometries. Finding an appropriate BRS operator in the case of the RP2 geometry, we generalize the background independent open string field theory (or boundary string field theory) of Witten on a unit disc. The coupling constant flow at the closed string side is driven by the scalar operator inserted at the nontrivial loop of RP2. We discuss the off-shell extension of the boundary/crosscap states. Our construction provides an interpolation of orientifold planes of various dimensions as well as that of D-branes. 
H. Itoyama, S. Nakamura