Gauged supergravities and their symmetry-breaking vacua in F-theory

We first derive a class of six-dimensional (1,0) gauged supergravities arising from threefold compactifications of F-theory with background fluxes. The derivation proceeds via the M-theory dual reduction on an SU(3)-structure manifold with four-form G_4-flux. We then show that vacuum solutions of these six-dimensional theories describes four-dimensional flat space times a compact two-dimensional internal space with additional localized sources. This induces a spontaneous compactification to four space-time dimensions and breaks the supersymmetry from N=2 to N=1, which allows the reduced theory to have a four-dimensional chiral spectrum. We perform the reduction explicitly and derive the N=1 characteristic data of the four-dimensional effective theory. The match with fourfold reductions of F-theory is discussed and many of the characteristic features are compared. We comment, in particular, on warping effects and one-loop Chern-Simons terms generically present in four-dimensional F-theory reductions.