Massive type-IIA theory on K3

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 wi th an action that is manifestly invariant under an O(4, 20)/ O(4) x O(20) d uality symmetry. We discover that this six-dimensional theory interpolates between vacua of ten-dimensional massive IIA supergravity and vacua of mass less IIA supergravity with appropriate background fluxes turned on. This in turn suggests a new 11-dimensional interpretation for the massive type-IIA theory.