Non-Abelian expansion of S-matrix elements and non-Abelian tach.yon DBI action

摘要

We apply the prescription proposed in hep-th/0307197 for non-Abelian expansion of S-matrix elements. to the S-matrix element of four tachyons and one gauge field in superstring theory. We show that the leading order terms of the expansion are in perfect agreement with the non-Abelian generalization of the tachyon DBI action in which the tachyon potential is V(T) = I + pi alpha'm(2)T(2) + 1/2! (pi alpha m(2)T(2))2 +... where m(2 =) -1/(2 alpha') is the mass of tachyon. This calculation fixes the coefficient of four-tachyon couplings without on-shell ambiguity. (C) 2006 Elsevier B.V. All rights reserved.