U-duality and D-brane Combinatorics
Abstract
We investigate D-brane instanton contributions to R^4 couplings in any toroidal compactification of type II theories. Starting from the 11D supergravity one-loop four-graviton amplitude computed by Green, Gutperle and Vanhove, we derive the non-perturbative O(e^{-1/\lambda}) corrections to R^4 couplings by a sequence of T-dualities, and interpret them as precise configurations of bound states of D-branes wrapping cycles of the compactification torus. Dp-branes explicitely appear as fluxes on D(p+2)-branes, and as gauge instantons on D(p+4)-branes. Specific rules for weighting these contributions are obtained, which should carry over to more general situations. Furthermore, it is shown that U-duality in D<=6 relates these D-brane configurations to O(e^{-1/\lambda^2}) instantons for which a geometric interpretation is still lacking.
Cite
@article{arxiv.hep-th/9710078,
title = {U-duality and D-brane Combinatorics},
author = {B. Pioline and E. Kiritsis},
journal= {arXiv preprint arXiv:hep-th/9710078},
year = {2009}
}
Comments
17 pages, LaTeX2e, intro. shortened and minor typos corrected, final version