The image effective action of F-theory compactifications Original Research Article

The four-dimensional image effective action of F-theory compactified on a Calabi–Yau fourfold is studied by lifting a three-dimensional M-theory compactification. The lift is performed by using T-duality realized via a Legendre transform on the level of the effective action, and the application of vector-scalar duality in three dimensions. The leading order Kähler potential and gauge-kinetic coupling functions are determined. In these compactifications two sources of gauge theories are present. Space–time filling non-Abelian seven-branes arise at the singularities of the elliptic fibration of the fourfold. Their couplings are included by resolving the singular fourfold. Generically a image gauge theory arises from the R–R bulk sector if the base of the elliptically fibered Calabi–Yau fourfold supports 2r harmonic three-forms. The gauge coupling functions depend holomorphically on the complex structure moduli of the fourfold, comprising closed and open string degrees of freedom. The four-dimensional electro-magnetic duality is studied in the three-dimensional effective theory obtained after M-theory compactification. A discussion of matter couplings transforming in the adjoint of the seven-brane gauge group is included.