Inverse KLT kernel of AdS string integrals from the intersection matrix

Abstract

We develop a topological and combinatorial interpretation of the Kawai--Lewellen--Tye (KLT) relations for $n$-point AdS string-amplitude building blocks, which are disk integrals with multivariable multiple polylogarithm insertions and sphere integrals with their single-valued counterparts. Building on the framework of twisted de Rham theory over a noncommutative ring, we reformulate the problem in terms of associahedral chambers of the moduli space loaded with solutions of the Knizhnik--Zamolodchikov equation. We construct regularized twisted cycles and express their intersection pairings through local monodromies and Drinfeld associators, which control transport between fusion-tree normalizations. Organizing the intersection contributions by common boundary faces yields the intersection matrix, which is identified with the inverse KLT kernel by the twisted period relation. The field-theory limit of the inverse KLT kernel is also given.

arXiv comment64 pages, 12 figures