Model Building and Phenomenology of Flux-Induced Supersymmetry Breaking on D3-branes

TL;DR

The paper provides a concrete string-theoretic realization of flux-induced supersymmetry breaking on D3-branes at singularities, demonstrating how NSNS and RR 3-form fluxes generate both soft SUSY-breaking terms and a mu-term in locally chiral models and embedding them into global flux compactifications. By constructing a local ${f Z}_4$ model and a global ${f Z}_4$ flux vacuum, it shows that the low-energy spectrum can resemble MSSM features and that the soft parameters are dictated by the background flux, yielding a dilaton-dominated-like pattern with universal soft terms. A key phenomenological insight is that flux quantization ties the mu-term and soft masses together, which can alter the conventional electroweak fine-tuning expectations; depending on Kähler moduli stabilization, the tuning with respect to the soft scale may be linear, constant, or even more favorable in higher-scale scenarios. The analysis highlights how global consistency conditions, flux quantization, and NSNS tadpoles shape viable vacua and their electroweak phenomenology, offering a framework for exploring more realistic flux vacua and their collider/cosmological implications.

Abstract

We study supersymmetry breaking effects induced on D3-branes at singularities by the presence of NSNS and RR 3-form fluxes. First, we discuss some local constructions of chiral models from D3-branes at singularities, as well as their global embedding in flux compactifications. The low energy spectrum of these constructions contains features of the supersymmetric Standard Model. In these models, both the soft SUSY parameters and the mu-term are generated by turning on the 3-form NSNS and RR fluxes. We then explore some model-independent phenomenological features as, e.g., the fine-tuning problem of electroweak symmetry breaking in flux compactifications. We also comment on other phenomenological features of this scenario.

Figures (8)

• Figure 1: Flux-induced Supersymmetry Breaking scenario, for the particular case of D3-branes at singularities. The D3-branes sit at a singularity of the internal space ${\cal M}_6$, in order to achieve a chiral gauge theory. The geometrical background preserves ${\cal N}=1$ supersymmetry but the 3-form flux $G_3$ surrounding the singularity breaks it, inducing soft terms in the gauge theory.
• Figure 2: Quiver diagram of the ${\bf Z}_4$ orbifold. Here the nodes represent $U(n)$ gauge groups and the arrows bifundamental $(n,\bar{n'})$ representations of left-handed chiral multiplets between them, pointing in the sense of the anti-fundamental.
• Figure 3: Folding of the ${\bf Z}_4$ quiver diagram in Figure \ref{['quiverZ4']} to the corresponding orientifold with vector structure. The colored nodes represent pairs of $U(n)$ gauge groups identified under the action of $\Omega {\cal R}$, while the white nodes are $U(m)$ gauge groups projected to either $SO(m)$ or $USp(m)$.
• Figure 6: Pati-Salam ${\bf Z}_4$ orientifold model with two-generations.
• Figure 7: Representation of the fixed sets of the ${\bf T}^6/{\bf Z}_4$ orbifold. The three squares represent the three ${\bf T}^2$ tori. Dots are fixed points in the torus and a grid in a square corresponds to a fixed torus.