HET journal club by Piotr Tourkine (Saclay) – Niels Bohr Institute - University of Copenhagen

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HET journal club by Piotr Tourkine (Saclay)

A non-renormalisation theorem in heterotic string theory and some of its consequences in N=4 supergravity

In this talk I will review how string theory can be used to compute amplitudes in field theory and in particular why it is an excellent tool to understand their UV behavior. I shall then explain how the non-renormalisation theorem in heterotic string applies to N=4 supergravity four graviton amplitudes (with or without matter). This provides a string theoretical explanation for the vanishing of the three loop divergence in four dimension for N=4 supergravity, or two loops in five dimensions. It predicts as well that divergences should begin to occur from the four loop order on in four dimensions.