Fundamental String Solutions in Open String Field Theories
  In Witten's open cubic bosonic string field theory and Berkovits' superstring field theory we investigate solutions of the equations of motion with appropriate source terms, which correspond to Callan-Maldacena solution in Born-Infeld theory representing fundamental strings ending on the D-branes. The solutions are given in order by order manner, and we show some full order properties in the sense of (alpha)'-expansion. In superstring case we show that the solution is 1/2 BPS in full order. 
Yoji Michishita