Notes on the overall coefficient of the two-loop superstring amplitude using pure spinor

Abstract

Using the results recently obtained for computing integrals over (non-minimal) pure spinor superspace, we compute the coefficient of the massless two-loop four-point amplitude from first principles. This proceeding is a very short summary on the paper [arXiv:1003.0678 [hep-th]], which was done with the collaboration of Carlos R. Mafra.