A bstract We study the building blocks of open and closed string amplitudes on AdS. These are given by two infinite towers of world-sheet integrals generalising the Euler and complex beta functions respectively. We show that the open and closed building blocks are related by an AdS version of the KLT relations, whose Kernel can be computed exactly. We furthermore show that the building blocks for open string amplitudes are given by Aomoto-Gelfand hypergeometric functions, and give their closed-form expression up to weight four.
Alday et al. (Wed,) studied this question.