Fractional Branes and Dynamical Supersymmetry Breaking
Sebastian Franco, Amihay Hanany, Fouad Saad, Angel M. Uranga
TL;DR
We study gauge theories on fractional branes at toric Calabi–Yau singularities and classify their IR dynamics into deformation, N=2, and dynamical SUSY breaking (DSB) sectors.The analysis combines field-theory techniques, brane tilings, and toric-deformation criteria, showing that non-perturbative ADS superpotentials generically drive DSB when supersymmetric flat directions are absent or when FI terms are dynamical ($N_f<N_c$ scenarios are central). Alongside, dynamical FI terms or dibaryons induce runaway directions rather than stable SUSY vacua.These results apply across multiple families (dP1, SPP, higher del Pezzo, and Y^{p,q}) and imply that infrared smoothing of warped throat geometries with 3-form fluxes is unlikely to be achieved by supersymmetric complex deformations; instead, any smoothing would be non-supersymmetric and potentially unstable.Brane tilings provide a practical framework to visualize and compute IR dynamics, connecting rank assignments to beta-function relations and to baryonic U(1) symmetries, thereby clarifying when deformation, N=2, or DSB behavior arises.
Abstract
We study the dynamics of fractional branes at toric singularities, including cones over del Pezzo surfaces and the recently constructed Y^{p,q} theories. We find that generically the field theories on such fractional branes show dynamical supersymmetry breaking, due to the appearance of non-perturbative superpotentials. In special cases, one recovers the known cases of supersymmetric infrared behaviors, associated to SYM confinement (mapped to complex deformations of the dual geometries, in the gauge/string correspondence sense) or N=2 fractional branes. In the supersymmetry breaking cases, when the dynamics of closed string moduli at the singularity is included, the theories show a runaway behavior (involving moduli such as FI terms or equivalently dibaryonic operators), rather than stable non-supersymmetric minima. We comment on the implications of this gauge theory behavior for the infrared smoothing of the dual warped throat solutions with 3-form fluxes, describing duality cascades ending in such field theories. We finally provide a description of the different fractional branes in the recently introduced brane tiling configurations.
