Solutions from boundary condition changing operators in open string field theory

Abstract

We construct analytic solutions of open string field theory using boundary condition changing (bcc) operators. We focus on bcc operators with vanishing conformal weight such as those for regular marginal deformations of the background. For any Fock space state ϕ, the component string field $\left\langle {\phi, \Psi } \right\rangle$ of the solution Ψ exhibits a remarkable factorization property: it is given by the matter three-point function of ϕ with a pair of bcc operators, multiplied by a universal function that only depends on the conformal weight of ϕ. This universal function is given by a simple integral expression that can be computed once and for all. The three-point functions with bcc operators are thus the only needed physical input of the particular open string background described by the solution. We illustrate our solution with the example of the rolling tachyon profile, for which we prove convergence analytically. The form of our solution, which involves bcc operators instead of explicit insertions of the marginal operator, can be a natural starting point for the construction of analytic solutions for arbitrary backgrounds.