Natalia Saulina

Compact F-theory GUTs with U(1) (PQ)

We construct semi-local and global realizations of SU(5) GUTs in F-theory that utilize a U(1)PQ symmetry to protect against dimension four proton decay. Symmetries of this type, which assign charges to Hu and Hd that forbid a tree level μ term, play an important role in scenarios for neutrino physics and gauge mediation that have been proposed in local F-theory model building. As demonstrated in [1], the presence of such a symmetry implies the existence of non-GUT exotics in the spectrum, when hypercharge flux is used to break the GUT group and to give rise to doublet-triplet splitting. These exotics are of precisely the right type to solve the unification problem in such F-theory models and might also comprise a non-standard messenger sector for gauge mediation. We present a detailed description of models with U(1)PQ in the semi-local regime, which does not depend on details of any specific Calabi-Yau four-fold, and then specialize to the geometry of [2] to construct three-generation examples with the minimal allowed number of non-GUT exotics. Among these, we find a handful of models in which the D3-tadpole constraint can be satisfied without requiring the introduction of anti-D3-branes, though this analysis does not incorporate contributions from additional fluxes that will ultimately be needed for moduli stabilization. Finally, because SU(5) singlets that carry U(1)PQ charge may serve as candidate right-handed neutrinos or can be used to lift the exotics, we study their origin in compact models and motivate a conjecture for how to count their zero modes in a semi-local setting.

F-theory Compactifications for Supersymmetric GUTs

We construct a family of elliptically fibered Calabi-Yau four-folds Y_4 for F-theory compactifications that realize SU(5) GUTs in the low-energy limit. The three-fold base X_3 of these fibrations is almost Fano and satisfies the topological criteria required to ensure that the U(1)_Y gauge boson remains massless, while allowing a decoupling of GUT and Planck scale physics. We study generic features of these models and the ability to engineer three chiral generations of MSSM matter. Finally, we demonstrate that it is relatively easy to implement the topological conditions required to reproduce certain successful features of local F-theory models, such as the emergence of flavor hierarchies.

Gauge mediation in F -theory GUT models

We study a simple framework for gauge-mediated supersymmetry breaking in local grand unified theory (GUT) models based on F-theory 7-branes and demonstrate that a mechanism for solving both the µ and µ/B_µ problems emerges in a natural way. In particular, a straightforward coupling of the messengers to the Higgs sector leads to a geometry which not only provides us with an approximate U(1)_(PQ) symmetry that forbids the generation of µ at the GUT scale, it also forces the SUSY-breaking spurion field to carry a nontrivial Peccei-Quinn (PQ) charge. This connects the breaking of supersymmetry (SUSY) to the generation of µ so that the same scale enters both. Moreover, the messenger sector naturally realizes the D3-instanton triggered SUSY-breaking model of [J. Heckman, J. Marsano, N. Saulina, S. Schafer-Nameki, and C. Vafa, arXiv:0808.1286.] so this scale is exponentially suppressed relative to M_(GUT). The effective action at low scales is in fact precisely of the form of the “sweet spot supersymmetry” scenario studied by Ibe and Kitano in [M. Ibe and R. Kitano, J. High Energy Phys. 08 (2007) 016.].

F -theory GUTs with U ( 1 ) symmetries: Generalities and survey

We study the structure of

A note on G-fluxes for F-theory model building

SU(5)

Topological boundary conditions in abelian Chern-Simons theory

F

Chern–Simons–Rozansky–Witten topological field theory

-theory grand unified theory (GUT) models that engineer additional

Global gluing and G-flux

U(1)

A note on Wilson–ʼt Hooft operators

symmetries. These are highly constrained by a set of relations observed by Dudas and Palti (DP) that originate from the physics of four-dimensional anomaly cancellation. Using the DP relations, we describe a general tension between unification and the suppression of dimension 5 proton decay when one or more