Towards Complete String Effective Actions Beyond Leading Order
Kasper Peeters, Pierre Vanhove, Anders Westerberg · 2003
Abstract: We review the current knowledge of higher-derivative terms in string effective actions, the various approaches that have been used to obtain them and their applications. 1 Higher-derivative string effective actions Many aspects of low-energy string dynamics can be captured in terms of a Wilsonian effective gravity field theory for the massless modes. Although it is often sufficient to consider only the lowest-order supergravity actions, there are qualitative string predictions for which knowledge about the subleading terms is required. Despite the fact that the first results about the structure of higher-derivative string effective actions are almost twenty years old, complete, supersymmetric invariants are still lacking, even at the first sub-leading order in α ′ beyond the supergravity level. Four main techniques have been employed to derive supersymmetric higher-derivative string effective actions. One is to simply try to construct the most general supersymmetric invariant containing higher derivatives. Such an approach was pursued in the early days [1], but it is extremely cumbersome (even on a computer) due to the enormous number of terms and the problem of dealing with side relations such as Bianchi