Gluon interactions and string theory

by Stieberger, S. (Universität Munich)

Tuesday 13 Dec 2005, 14:00 → 15:00 Europe/Zurich

TH Auditorium (CERN)

We investigate higher order gauge interactions by computing N gluon open superstring disk amplitudes. For example, the case N = 6 probes the higher order gauge terms with six external legs on Dp-branes, such as F⁶ and the terms D⁴ F⁴, D² F⁵, D⁶ F⁴, D² F⁶, ... leading to a non-trivial generalization of the famous Born-Infeld action. The full string S-matrix results may be nicely summarized in a very compact and intriguing form capturing the a' -expansion of the effective action. We discuss how these tree-level type-I couplings map in a non-trivial way to the same couplings on the dual heterotic side at higher loop. Moreover, a subsector of these amplitudes, namely their MHV part, generalizes recently discussed properties in twistor space. We present powerful tools for computing multiple gluon open superstring disk amplitudes: a systematic and efficient method to calculate tree-level string amplitudes and relations between multiple hypergeometric functions and their a'-(momentum)-expansions given by (generalized) multiple Euler-Zagier sums.