Romans type IIA theory and the heterotic strings

TL;DR

This paper explores the duality symmetries in compactified massive type IIA supergravity with fluxes, establishing connections to heterotic string solutions through geometric and flux configurations.

Contribution

It demonstrates how specific duality transformations relate massive type IIA on K3×T^2 with fluxes to heterotic string solutions, revealing new links between these theories.

Findings

Duality symmetry group: SL(2,R)×SL(2,R)×O(4,20)

Relation between massive type IIA on K3×T^2 and heterotic strings

Wrapped D8-brane solution corresponds to heterotic pure gravity solution

Abstract

In this paper we study $T^2$ compactification of 6-dimensional massive type IIA supergravity in presence of Ramond-Ramond background fluxes. The resulting theory in four dimensions is shown to possess $SL(2,R)\times SL(2,R)\times O(4,20)$ duality symmetry. It is shown that specific elements of this symmetry relate massive type IIA compactified on $K3\times T^2$ (with fluxes along $K3$) to the ordinary type IIA compactified on $K3\times T^2$ (with fluxes along $T^2$). In turn, this relationship is exploited to relate Romans theory to heterotic strings. The D8-brane (domain-wall) wrapped on $K3\times T^2$ is related to {\it pure gravity} heterotic solution which is a direct product of 6-dimensional flat spacetime and a 4-dimensional Taub-NUT instanton.