John H. Schwarz

TL;DR: In this paper, the covariant two-dimensional action principle that describes the dynamics of free superstrings in a Minkowski background is reviewed, and covariant gauge conditions are formulated, which simplify the equations of motion of the superspace coordinates to free equations.

TL;DR: In this article, Green, John Schwarz, and Edward Witten published two volumes on string theory, one concerned with the evaluation of one-loop amplitudes, the study of anomalies and phenomenology, and the emergence of the gauge groups E8 x E8 and SO(32).

TL;DR: The higher-order contact terms of the low-energy effective supergravity field theories arise from the exchange of massive superstring states as discussed by the authors, which may be regarded as string generalizations of a cubic Yang-Mills coupling and a cubic gravity coupling.