Preprint 2018-02
Johannes Broedel, Oliver Schlotterer, Federico Zerbini
From elliptic multiple zeta values to modular graph functions: open and closed strings at one loop.
Abstract: We relate one-loop scattering amplitudes of massless open- and closed-string states at the level of their low-energy expansion. The modular graph functions resulting from integration over closed-string punctures are observed to follow from symmetrized open-string integrals through a tentative generalization of the single-valued projection known from genus zero.
Preprint series: Institut für Mathematik, Humboldt-Universität zu Berlin (ISSN 0863-0976), 2018-02
63 pp.