Abstract. We talk about S-matrix element of one closed string RR field, two open string tachyons and one gauge field in type II superstring theory in brane -anti brane systems. An expansion for the S-matrix element has been found that all leading order terms are exactly reproduced by the symmetric trace tachyon DBI and the Wess-Zumino actions of D-brane-anti-D-brane systems. Using this consistency, we have also found the higher derivative correction to the some of the WZ terms as well. Then we talk about the precise consistency between field theory and string theory tachyon pole of S-matrix element of one RR and three tachyons provided that one takes into account the fact that the tachyon vertex operator in 0 picture to be along the Pauli matrix $\sigma_1$ whereas the tachyon in -1 picture to be along the $\sigma_2$ direction. This internal CP factors must be included in the tachyon DBI part of the effective action. Finally we give some hints for tachyonic effective action for non-BPS branes and BPS brane such that the infinite tachyon/massless poles and the contact terms of amplitudes can be reproduced by the tachyon DBI and the WZ actions, and by their higher derivative corrections.
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