Tachyon Dynamics in Open String Theory
Abstract
In this review we describe our current understanding of the properties of open string tachyons on an unstable Dbrane or braneantibrane system in string theory. The various string theoretic methods used for this study include techniques of twodimensional conformal field theory, open string field theory, boundary string field theory, noncommutative solitons, etc. We also describe various attempts to understand these results using field theoretic methods. These field theory models include toy models like singular potential models and padic string theory, as well as more realistic version of the tachyon effective action based on DiracBornInfeld type action. Finally we study closed string background produced by the "decaying" unstable Dbranes, both in the critical string theory and in the twodimensional string theory, and describe the open string completeness conjecture that emerges out of this study. According to this conjecture the quantum dynamics of an unstable Dbrane system is described by an internally consistent quantum open string field theory without any need to couple the system to closed strings. Each such system can be regarded as a part of the "hologram" describing the full string theory.
 Publication:

International Journal of Modern Physics A
 Pub Date:
 2005
 DOI:
 10.1142/S0217751X0502519X
 arXiv:
 arXiv:hepth/0410103
 Bibcode:
 2005IJMPA..20.5513S
 Keywords:

 Boundary conformal field theory;
 open string field theory;
 tachyon condensation;
 twodimensional string theory;
 High Energy Physics  Theory
 EPrint:
 LaTex file, 169 pages, based on lectures at various schools