Massive Type IIA Theory on K3

TL;DR

The paper shows that compactifying ten-dimensional massive IIA supergravity on $K3$ with all RR background fluxes produces a new six-dimensional massive (gauged) supergravity whose action is invariant under $O(4,20)$ when the fluxes transform as a vector under the duality. This framework unifies a broad class of massive theories and reveals that the six-dimensional theory interpolates between vacua of massive IIA and massless IIA with flux, hinting at an eleven-dimensional interpretation of Romans mass. Domain-wall solutions, including the D-8-brane wrapped on $K3$, are mapped via $O(4,20)$ duality to massless IIA vacua with RR flux, illustrating explicit connections between massive and massless backgrounds. The lift to M-theory identifies massive IIA on $K3$ with M-theory on $K3\times S^1$ with 4-form flux along $K3$, suggesting a duality extension where Romans mass corresponds to M-theory flux, and underscoring a richer web of relations among string backgrounds in the presence of flux.

Abstract

In this paper we study K3 compactification of ten-dimensional massive type IIA theory with all possible Ramond-Ramond background fluxes turned on. The resulting six-dimensional theory is a new massive (gauged) supergravity with an action that is manifestly invariant under an O(4,20) / (O(4) times O(20)) duality symmetry. We discover that this six-dimensional theory interpolates between vacua of ten-dimensional massive IIA supergravity and vacua of massless IIA supergravity with appropriate background fluxes turned on. This in turn suggests a new 11-dimensional interpretation for the massive type IIA theory.