A torsion-free background solution of the string theory

Abstract

We find a background solution of the string theory which has a special property distinguished from the usual background solutions. This background solution does not produce the NS-NS two-form fields under T-duality and therefore the background vacua described by this solution essentially do not involve NS-NS type branes in their configurations, unlike the case of the ordinary Calabi–Yau ansatz. As a result the non-linear [Formula: see text]-models, whose target space metrics are given by these T-dual partners, can both be torsion-free.