Humberto Gomez, Universidade Estadual Paulista
Scattering Amplitudes in the pure Spinor Formalism

We compute the coefficient of the massless tree-level, one, two-loop four-point amplitude from first principles. Contrasting with the mathematical difficulties in the RNS formalism where unknown normalizations of chiral determinant formula force the two-loop coefficient to be determined only indirectly through factorization, the computation in the pure spinor formalism can be smoothly carried out.