Advances in Theoretical and Mathematical Physics
Volume 15 (2011)
Breaking GUT groups in F-theory
Pages: 1523 – 1603
We consider the possibility of breaking the GUT group to theStandard Model gauge group in $F$-theory compactifications byturning on certain $U(1)$ fluxes. We show that the requirement ofmassless hypercharge is equivalent to a topological constraint onthe UV completion of the local model. The possibility of thismechanism is intrinsic to $F$-theory. We address some of thephenomenological signatures of this scenario. We show that ourmodels predict monopoles as in conventional GUT models. We discussin detail the leading threshold corrections to the gauge kineticterms and their effect on unification. They turn out to be relatedto Ray--Singer torsion. We also discuss the issue of proton decay in$F$-theory models and explain how to engineer models which satisfycurrent experimental bounds.