Abstract
We study a bosonic four-dimensional effective action corresponding to the heterotic string compactified on a six-torus (dilaton-axion gravity with one vector field) on a curved space-time manifold possessing a timelike Killing vector field. Previously the existence of the global symmetry ( duality) as well as the symmetric space property of the corresponding model have been established following the Neugebauer-Kramer approach. Here we present an explicit form of the generators in terms of coset variables and construct a representation of the coset in terms of the physical target space coordinates. A complex symmetric 2 × 2 matrix ("matrix dilaton-axion") is then introduced for which duality takes the matrix-valued form. In terms of this matrix the theory is further presented as a Kähler model. This leads to a more economic 2 × 2 formulation suggesting some new solution-generating techniques. A new solution (corresponding to constant ) is obtained which describes the system of point massless magnetic monopoles endowed with axion charges. In such a system mutual magnetic repulsion is exactly balanced by axion attraction so that the resulting space-time is locally flat but possesses multiple Taub-NUT singularities.
- Received 30 June 1995
DOI:https://doi.org/10.1103/PhysRevD.54.1656
©1996 American Physical Society