“…This untwisting procedure shifts the conformal anomaly contribution of the (Λ α , wα) variables from +32 to −16, so the untwisted BRST operator is no longer nilpotent. To make this untwisting procedure consistent at the quantum level, one needs to add to the RNS variables not only the (θ α , pα, Λ α , wα) variables, but also the non-minimal variables (Λα, w α , Rα, S α ) where (Λα, w α ) and (Rα, S α ) are 32 leftmoving bosons and fermions of conformal weight (0, 1)[10]. The non-minimal BRST operator is obtained…”