Application of KBc Subalgebra in String Field Theory

Abstract

Recently, a classical solution of open cubic string field theory (CSFT) which corresponds to the closed string vacuum is found by Erler and Schnabl. In their work, a very simple subalgebra of open string star algebra — called KBc subalgebra — plays a crucial role. In this talk, we demonstrate two applications of the KBc subalgebra. One is evaluation of classical and effective tachyon potential. It turns out that the level expansion in the KBc subalgebra terminates at a certain level, so that analytic evaluation of effective potential is available. The other application is regularization of the identity based solutions. It is demonstrated that the Okawa-Erler-Schnabl type solution naturally includes gauge invariant regularization of identity based solutions.