Relations between different amplitudes are crucial for our understanding of the structure of these observables. Inspired by a recursion for open-string tree-level amplitudes, and by a result of Brown–Dupont relating open- and closed-string tree-level amplitudes through a single-valued projection, I will show a recursion relation for closed-string tree-level amplitudes.By introducing closed-string analogues of Selberg integrals, which satisfy the Knizhnik–Zamolodchikov equation for a suitable matrix representation, the boundary values can be identified with n-point and (n-1)-point closed-string tree-level amplitudes, which are in turn related through the Deligne associator. (Based on work in progress with Johannes Broedel and Federico Zerbini.)
