# A torsion-free background solution of the string theory

## TL;DR

This paper presents a novel torsion-free background solution in string theory that remains free of NS-NS two-form fields under T-duality, leading to torsion-free non-linear sigma models unlike traditional Calabi-Yau backgrounds.

## Contribution

The authors introduce a unique background solution in string theory that avoids NS-NS fields and torsion, differing from standard Calabi-Yau solutions.

## Key findings

- The background solution does not produce NS-NS two-form fields under T-duality.
- The resulting sigma models are torsion-free.
- The solution is distinguished from usual backgrounds by its lack of NS-NS branes.

## 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, unlikely to the case of the ordinary Calabi-Yau ansatz. As a result the non-linear $\sigma$-models, whose target space metrics are given by these T-dual partners, can both be torsion-free.