A LARGE CLASS OF NEW GRAVITATIONAL AND AXIONIC BACKGROUNDS FOR FOUR-DIMENSIONAL SUPERSTRINGS

Abstract

A large class of new 4D superstring vacua with nontrivial/singular geometries, space–time supersymmetry and other background fields (axion, dilaton) are found. Killing symmetries are generic and are associated with nontrivial dilaton and antisymmetric tensor fields. Duality symmetries preserving N = 2 superconformal invariance are employed to generate a large class of explicit metrics for noncompact 4D Calabi–Yau manifolds with Killing symmetries. We comment on some of our solutions which have interesting singularity properties and cosmological interpretation.