title: Hypercharge flux, exotics, and anomaly cancellation in F-theory grand unification.
abstract: We sharpen constraints related to hypercharge flux in F-theory grand unified theories that possess U(1) symmetries and argue that they arise as a consequence of four-dimensional anomaly cancellation. This gives a physical explanation for all restrictions that were observed in spectral cover models while demonstrating that the phenomenological implications for a well-motivated set of models are not tied to any particular formalism.
authors.affiliation: Enrico Fermi Institute, University of Chicago, 5640 S Ellis Ave, Chicago, Illinois 60637, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Marsano