Quantization of the Superstring with Manifest U(5) Super-Poincare Invariance
arXiv:hep-th/9902099 · doi:10.1016/S0370-2693(99)00548-1
Abstract
The superstring is quantized in a manner which manifestly preserves a U(5) subgroup of the (Wick-rotated) ten-dimensional super-Poincaré invariance. This description of the superstring contains critical N=2 worldsheet superconformal invariance and is a natural covariantization of the U(4)-invariant light-cone Green-Schwarz description.
Added two comments on relation to light-cone gauge