Classical gauge and BRST structure of covariant heterotic strings

Abstract

We investigate the classical world-sheet gauge symmetries of heterotic string theories in the formalism of Siegel, which permits covariant gauge-fixing and BRST quantization. Siegel has demonstrated by algebraic considerations that superstrings possess two further gauge invariances, in addition to the usual general coordinate invariance and the “ k-supersymmetry” discovered by Green and Schwarz. We display the actions of the four gauge symmetries upon all fields, and compute the gauge algebra. The algebra only closes modulo the equations of motion, in principle necessitating arbitrarily complicated ghost interactions in a BRST quantization of the theory. However, the present situation is tractable, and we explicitly display the required BRST structure and ghost interactions.