Description
Abstract: This talk will start by recalling basics of string scattering amplitudes and the twisted (co-)homologies at the heart of intersection theory. I will then review the Kawai-Lewellen-Tye (KLT) relations between closed- and open-string tree amplitudes in flat background in the light of twisted intersection numbers. Recent progress on string amplitudes in AdS spacetime can be elegantly understood from a non-commutative version of intersection theory. I will finally discuss different flavors of loop-level KLT relations, namely those of so-called Riemann Wirtinger integrals as mathematical laboratories and those of loop integrands of closed-string one-loop amplitudes.