Maximally helicity violating disk amplitudes, twistors and transcendental integrals

We obtain simple expressions for tree-level maximally helicity violating amplitudes of N gauge bosons from disk world-sheets of open superstrings. The amplitudes are written in terms of (N−3)! hypergeometric integrals depending on kinematic parameters, weighted by certain kinematic factors. The integrals are transcendental in a strict sense defined in this work. The respective kinematic factors can be succinctly written in terms of “dual” momentum-twistors. The amplitudes are computed by using the prescription proposed by Berkovits and Maldacena.