Solving flavor puzzles with quiver gauge theories

Abstract

We consider a large class of models where the SU5 gauge symmetry and a Froggatt-Nielsen (FN) Abelian flavor symmetry arise from a U5 U5 quiver gauge theory. An intriguing feature of these models is a relation between the gauge representation and the horizontal charge, leading to a restricted set of possible FN charges. Requiring that quark masses are hierarchical, the lepton flavor structure is uniquely determined. In particular, neutrino mass anarchy is predicted.

On gauge couplings and thresholds in Type I Gepner models and otherwise

“…The Yukawa couplings φ5ψ1 0 χ1 0 , though SU(5) invariant, are forbidden by U(1) charge conservation and by the impossibility of generating the necessary antisymmetric tensor ǫ ijklm as Chan-Paton factor, i.e. taking traces of matrices [97,98]. Barring non-perturbative effects that can significantly change this state of affairs but whose study is only in its infancy, the best one can achieve is some L-R symmetric extension of the SM or a Pati-Salam generalization thereof, together with some (anomalous) U(1)'s.…”

Extracting Flavor from Quiver Gauge Theories

“…Here we restrict ourselves to a single U (1) FN and therefore by assumption there is only one field in the quiver, S, which spontaneously breaks the symmetry and obtains a small VEV, S /M = ε ≪ 1. As shown in [3], under these assumptions and due to the relation between the abelian and non-abelian charges, the largest possible suppression in such FN models is ε 3 . This result shows the strong predictive power that is added to the FN mechanism when embedded in string theory.…”

“…2. The U (1) is broken spontaneously [3]. The only way to do this without breaking the associated SU (N) gauge group is by considering a composite singlet composed of N fundamentals to obtain a VEV.…”

“…The U (1) is broken by non perturbative effects. Depending on the matter content, gauge theory instantons may be generated or otherwise stringy effects such as Dinstantons may break the U(1) [3,8].…”

“…This may happen in string theory. Below we consider string-inspired models in which the FN mechanism is embedded in quiver gauge theories [3]. These theories arise at low energy as the effective theories on D-branes placed at singular geometries [4,5].…”