New developments in string field theory

Progress in string field theory came to an abrupt halt a few years ago because of the failure to construct a covariant closed string field theory. Recently, the author and the Kyoto/MIT groups independently formulated the non-polynomial closed string field theory, thereby solving this problem. The original non-polynomial theory, however, is riddled with anomalies and violates modular invariance. We show that a second non-polynomial series is necessary to kill the anomalies and restore modular invariance. The non-polynomial theory can also be generalized to the geometric and the supersymmetric case. (author). 20 refs, 5 figs