Hypercharge flux in F-theory and the stable Sen limit
Andreas P. Braun, Andres Collinucci, Roberto Valandro
TL;DR
This work cungresses a robust framework to realize hypercharge flux in F-theory by lifting Type IIB F_2 fluxes through a stable Sen limit, clarifying the necessity of glue-vector data and non-factorizable four-cycles rather than simple pullbacks. The authors develop explicit prescriptions for constructing G_4 fluxes that keep U(1)_Y massless, apply them to SU(5) GUTs with U(1) restrictions, and demonstrate precise matches between IIB fluxes and F-theory four-form fluxes, including Cartan and hypercharge sectors. They provide concrete realizations in SU(2) and SU(5) setups, derive doublet–triplet splitting via hypercharge flux, and extend the lifting to brane/image-brane and Whitney-brane configurations in smooth Weierstrass models. Overall, the paper offers a concrete, geometrically controlled path to GUT breaking through hypercharge flux in F-theory with explicit flux lifts, matter content, and consistency checks (D3-tadpoles, chiral indices). The results enhance the viability and calculability of F-theory GUTs with massless hypercharge and realistic MSSM-like spectra.
Abstract
IIB compactifications enjoy the possibility to break GUT groups via fluxes without giving mass to the hypercharge gauge field. Although this important advantage has greatly motivated F-theory constructions, no such fluxes have been constructed directly in terms of the M-theory $G_4$-form. In this note, we give a general prescription for constructing hypercharge G-fluxes. By using a stable version of Sen's weak coupling limit, we verify their connection with IIB fluxes. We illustrate the lift of fluxes in a number of examples, including a compact ${\rm SU}(5) \times {\rm U}(1)$ model with explicit realization of doublet-triplet splitting. Finally, we prove an equivalence conjectured in an earlier work as a by-product.
