Stable vacua for tachyonic strings

Abstract

In addition to the familiar string theories with spacetime supersymmetry, there exist a number of nonsupersymmetric ten-dimensional superstrings. Nearly all of these theories have closed string tachyons, indicating a misidentification of the vacuum around which they are to be quantized. In this work, we identify (meta)stable vacua for all known tachyonic superstrings. These vacua are all lower dimensional, with most of them being familiar two-dimensional string theories. However, there are also intriguing examples of solutions in dimensions 6, 8, and 9, with respective gauge groups E7×E7, SU(16), and E8. These special vacua have positive vacuum energy and no moduli.