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Physics and Mathematics of Scattering Amplitudes Program Seminar: Stephan Stieberger

Stephan Stieberger

Title: Motivic Superstring Amplitudes
Speaker: Stephan Stieberger
Date: Thursday, November 14, 2013
Time: 11:00am – 12:30pm
Place: Seminar Room 313, Simons Center




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Abstract: The structure of tree-level open and closed superstring amplitudes is analyzed. For the open superstring amplitude we find a striking and elegant form, which is bolstered by the decomposition of motivic multiple zeta values. A morphism induced by the coproduct maps the the latter onto a non-commutative Hopf algebra. In terms of elements of this Hopf algebra the open superstring amplitude assumes a very simple and symmetric form, which carries all the relevant information. For the closed superstring amplitude we identify its alpha’-expansion as series with single-valued multiple zeta values as coefficients. The latter represent a subclass of multiple zeta values originating from single-valued multiple polylogarithms at unity. Moreover, the closed superstring amplitude can be cast into the same algebraic form as the open superstring amplitude: the closed superstring amplitude essentially is the single-valued version of the open superstring amplitude. This fact points into a deeper connection between gauge and gravity amplitudes than what is implied by Kawai-Lewellen-Tye relations.