A Review on Tachyon Condensation in Open String Field Theories

Abstract

We review the recent studies of tachyon condensation in string field theory. After introducing the open string field theory both for bosonic string and for superstring, we use them to examine the conjecture that the unstable configurations of the D-branes will decay into the 'closed string vacuum' through the tachyon condensation. And we describe the attemps to construct a lower-dimensional bosonic D-brane as an unstable lump solution of the string field equation. This paper is based on my master's thesis submitted to Department of Physics, Faculty of Science, University of Tokyo on January 2001.