Breaking GUT Groups in F-Theory
We consider the possibility of breaking the GUT group to the Standard Model gauge
group in F-theory compactifications by turning on certain U(1) fluxes. We show that the
requirement of massless hypercharge is equivalent to a topological constraint on the UV
completion of the local model. The possibility of this mechanism is intrinsic to F-theory.
We address some of the phenomenological signatures of this scenario. We show that our
models predict monopoles as in conventional GUT models. We discuss in detail the leading
threshold corrections to the gauge kinetic terms and their effect on unification. They turn
out to be related to Ray-Singer torsion. We also discuss the issue of proton decay in Ftheory
models and explain how to engineer models which satisfy current experimental
bounds.
