Relating the Rns and Pure Spinor Formalisms for the Superstring

Recently, the superstring was covariantly quantized using the BRST-like operator Q = λ α d α where λ α is a pure spinor and d α are the fermionic Green-Schwarz constraints. By performing a field redefinition and a similarity transformation, this BRST-like operator is mapped to the sum of the Ramond-Neveu-Schwarz BRST operator and η 0 ghost. This map is then used to relate physical vertex operators and tree amplitudes in the two formalisms. Furthermore, the map implies the existence of a b ghost in the pure spinor formalism which might be useful for loop amplitude computations.