From multiple unitarity cuts to the coproduct of Feynman integrals

75 pages, 13 figuresInternational audienceWe develop techniques for computing multiple unitarity cuts of Feynman integrals and reconstructing the integral from these cuts. We study the relations among unitarity cuts computed via diagrammatic cutting rules, the discontinuity across the corresponding branch cut, and the coproduct of the integral. For single unitarity cuts, these relations are familiar. Here we show that they can be generalized to sequences of unitarity cuts in different channels. Using concrete one- and two-loop scalar integral examples we demonstrate that it is possible to reconstruct (the symbol of) a Feynman integral from either single or double unitarity cuts. Our results offer insight into the analytic structure of Feynman integrals as well as a new approach to computing them