Equivalence of Two-Loop Superstring Amplitudes in the Pure Spinor and   RNS Formalisms
  The pure spinor formalism for the superstring has recently been used to compute massless four-point two-loop amplitudes in a manifestly super-Poincare covariant manner. In this paper, we show that when all four external states are Neveu-Schwarz, the two-loop amplitude coincides with the RNS result. 
Nathan Berkovits and Carlos R. Mafra (IFT-UNESP, Sao Paulo)