Flux-induced Soft Terms on Type IIB/F-theory Matter Curves and Hypercharge Dependent Scalar Masses

TL;DR

This work computes flux-induced SUSY-breaking soft terms for D7-branes and chiral matter on F-theory matter curves within type IIB orientifolds, incorporating ISD and IASD G3 flux, worldvolume magnetic flux, and backreaction from distant branes. By combining DBI+CS mindset with local wavefunction analysis, the authors derive explicit soft-term patterns for bulk adjoints and bifundamental matter, revealing hypercharge-dependent non-universal scalar masses and possible flavor-violating effects. They connect these results to modulus-dominated SUSY breaking in simple N=1 supergravity frameworks and explore the impact of magnetic flux on curves, as well as the role of distant branes and compactification. The paper then applies the results to local SU(5) GUTs, showing how hypercharge flux can generate distinctive sfermion hierarchies and discussing implications for FCNC constraints and Higgs mass fine-tuning, with broader relevance for phenomenology of F-theory compactifications. Overall, it provides a detailed microscopic bridge between closed-string backgrounds and low-energy soft terms in realistic string-inspired models.

Abstract

Closed string fluxes induce generically SUSY-breaking soft terms on supersymmetric type IIB orientifold compactifications with D3/D7 branes. This was studied in the past by inserting those fluxes on the DBI+CS actions for adjoint D3/D7 fields, where D7-branes had no magnetic fluxes. In the present work we generalise those computations to the phenomenologically more relevant case of chiral bi-fundamental fields laying at 7-brane intersections and F-theory local matter curves. We also include the effect of 7-brane magnetic flux as well as more general closed string backgrounds, including the effect of distant (anti-)D3-branes. We discuss several applications of our results. We find that squark/slepton masses become in general flux-dependent in F-theory GUT's. Hypercharge-dependent non-universal scalar masses with a characteristic sfermion hierarchy m_E^2 < m_L^2 < m_Q^2 < m_D^2 < m_U^2 are obtained. There are also flavor-violating soft terms both for matter fields living at intersecting 7-branes or on D3-branes at singularities. They point at a very heavy sfermion spectrum to avoid FCNC constraints. We also discuss the possible microscopic description of the fine-tuning of the EW Higgs boson in compactifications with a MSSM spectrum.

Figures (2)

• Figure 1: Summary of the type of sources that are present in a standard phenomenological IIB orientifold compactification. The SM is located in a stack of intersecting D7-branes with a higher dimensional SU(5) GUT structure. Apart from topologically non-trivial closed string 3-form fluxes $G_3$ , there are distant localized sources that may also contribute to SUSY-breaking and/or moduli stablization. These include gaugino condensation in the worldvolume of D7-branes, self-dual magnetic fluxes also in the worldvolume of D7-branes and/or anti-D3-branes. The effect of distant sources in the effective theory on the worldvolume of the SM D7-branes can be studied in terms of their backreaction in the local patch.
• Figure 2: A stack of $\overline{\rm D3}$-branes on the opposite side of the magnetized D7-branes.