Quantization of the superstring with manifest U(5) super-Poincaré invariance

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.