# Unwinding strings in semi-flatland

## TL;DR

This paper investigates the behavior of winding strings around T-duality defects, revealing that near-core physics involves non-geometric modes beyond supergravity, and constructs a double field theory solution to model these effects.

## Contribution

It introduces a double field theory solution capturing the near-core physics of winding strings around T-duality defects, highlighting non-geometric modes beyond supergravity.

## Key findings

- Winding modes near T-duality defects involve non-geometric physics.
- Supergravity approximation does not capture near-core winding physics.
- Constructed a double field theory solution modeling these effects.

## Abstract

We study the dynamics of strings with non-zero winding number around T-duality defects. We deduce that the physics near the core of such non-geometric objects involves winding modes that are not captured by the supergravity approximation, and we argue that such corrections are T-dual to the modes responsible for quantum corrections of semi-flat elliptic metrics. We furthermore construct a solution of double field theory that captures part of such near-core physics.