Lorentz-Covariant Lagrangian Formulation of the Interacting Heterotic String Theory

Abstract

A manifestly Lorentz·covariant lagrangian formulation of the N eveu·Schwarz· Ramond heterotic string interacting with external fields is presented. The action is derived from the action for fully 26·dimensional semi·superstring by a simple ansatz. The compactification occurs automatically due to the heterotic structure. The requirement of superconformal symmetry, necessary to guarantee the absence of ghosts, plays an important role in the formulation. The so· called twist factors also are involved in the theory without introducing them by hands. The toric internal space necessitates a special treatment with respect to the Poisson brackets. l ) has spark­ ed a new revival of the string model as a strong candidate for the unified theory of fundamental interactions. In the low-energy field theory of the superstring (SST-I) they have found that the gravitational and non-Abelian anomalies cancel if and only if the gauge group incorporated in the model is either 50(32) or E8 X E8. In SST the gauge group has been introduced by the Chan-Paton method, but the phenomenologically promising gauge group E8 X E8 cannot be derived in this way. Therefore, the Frenkel-Kac construction 2 ) of the gauge group has focused much