Boundary states in open string channel and CFT near corner

We generalize the idea of boundary states to open string channel. They describe emission and absorption of open strings in the presence of intersecting D-branes. We construct the explicit oscillator representation for the free boson and fermionic ghost. Inner product between such states describes a disk amplitude with the shape of a rectangle and has the modular covariance with a nontrivial conformal weight. We compare the result with those obtained by two different methods. One is the path integral formalism and the other is by conformal anomaly, and they give consistent results. We have to be careful of the singularity of the CFT near the corners. In particular, we derive the correction of conformal weight of the primary field inserted at the corner and it gives the modular weight of the rectangle amplitude. We also provide explicit computations of the correlation functions. ∗e-mail address: [email protected] †e-mail address: [email protected] ‡e-mail address: [email protected]