F-theory is a branch of
string theorydeveloped by Cumrun Vafa. The new vacua described as F-theory were discovered by Vafa, and it also allowed string theorists to construct new realistic vacua — in the form of F-theory compactified on elliptically fibered Calabi-Yaufour-folds. The letter "F" stands for "Father" much like the "M" in M-theoryis often taken to stand for "Mother".
F-theory is formally a 12-dimensional theory, but the only way to obtain an acceptable background is to compactify this theory on a two-torus. By doing so, we obtain type IIB
superstring theoryin 10 dimensions. The SL(2,Z) S-dualitysymmetry of the resulting type IIB string theory is manifest because it arises as the group of large diffeomorphisms of the two-dimensional torus.
More generally, one can compactify F-theory on an elliptically fibered
manifold( elliptic fibration), i.e. a fiber bundlewhose fiber is a two-dimensional torus (also called an elliptic curve). For example, a subclass of the K3 manifolds is elliptically fibered, and F-theory on a K3 manifold is dual to heterotic stringtheory on a two-torus. (Eight dimensions are large.)
The well-known large number of semirealistic solutions to string theory referred to as
string theory landscape, with elements or so, is dominated by F-theory compactifications on Calabi-Yau four-folds.
Extra time dimensions
F-theory, as it has
metric signature(11,1), is not a "two-time" theory of physics.string-theory-stub theory is a partial equation theory only of the branescape.
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