Family symmetries in F-theory GUTs

Abstract:We discuss the origin of both non-Abelian discrete family symmetry and Abelian continuous family symmetry, as well as matter parity, from F-theory SUSY GUTs. We propose a minimal model based on the smallest GUT group SU(5), together with the non-Abelian family symmetry D 4 plus an Abelian family symmetry, where fluxes are responsible for doublet-triplet splitting, leading to a realistic low energy spectrum with phenomenologically acceptable quark and lepton masses and mixing. We show how a Z 2 matter parity emerging from F-theory can suppress proton decay while allowing neutronantineutron oscillations, providing a distinctive signature of the set-up.

Section: Jhep10(2015)041mentioning

confidence: 99%

“…We can interpret these results as a multifurcation to irreducible representations of the D 4 group. If we further assume a 1 → µa 6 , then 11) and the tens of the GUT group now become:…”

Section: Reconciling Interpretationsmentioning

confidence: 99%

Phenomenological implications of a minimal F-theory GUT with discrete symmetry

Karozas

King

Leontaris

et al. 2015

“…However the structure of the low dimension terms is determined by the SU(3) symmetry and so for the discussion here it does not matter that only a discrete subgroup is unbroken. Finally we consider a model [39] with three Abelian factors based on the structure found in F-theory string models [38] in which the family symmetry is a subgroup of the underlying E(8) string symmetry. In this the emergence of three Abelian factors is natural and unlike the previous models the charges of the fermions are strongly constrained by the E(8) symmetry.…”

Section: Family Symmetry Modelsmentioning

confidence: 99%

“…These symmetries and the charges of the matter fields under these symmetries are strongly constrained by the underlying E(8) symmetry of the associated string theory [38]. To illustrate the structure that can emerge we include here an Ftheory model [39] with an underlying SU(5) GUT symmetry. In this model there is a U(1) 3 family symmetry, a subgroup of the SU(5) ⊥ subgroup of E(8) ( SU(5) × SU(5) ⊥ ⊂ E(8)) when a Z 2 monodromy is imposed.…”

Section: A Family Symmetry Modelsmentioning

confidence: 99%

Beyond MFV in family symmetry theories of fermion masses

Lalak

Pokorski

Ross

2010

Minimal Flavour Violation (MFV) postulates that the only source of flavour changing neutral currents and CP violation, as in the Standard Model, is the CKM matrix. However it does not address the origin of fermion masses and mixing and models that do usually have a structure that goes well beyond the MFV framework. In this paper we compare the MFV predictions with those obtained in models based on spontaneously broken (horizontal) family symmetries, both Abelian and non-Abelian. The generic suppression of flavour changing processes in these models turns out to be weaker than in the MFV hypothesis. Despite this, in the supersymmetric case, the suppression may still be consistent with a solution to the hierarchy problem, with masses of superpartners below 1 TeV. A comparison of FCNC and CP violation in processes involving a variety of different family quantum numbers should be able to distinguish between various family symmetry models and models satisfying the MFV hypothesis.

“…As such, with Eqs. (24,25) also imposed, the multiplicities can be written in terms of the dot products Table 2: Multiplicities of the E 6 exotics in terms of the topological numbers A, B,C (see text).…”

Section: A More General Casementioning

confidence: 99%

Gauge coupling unification in E 6 F-theory GUTs with matter and bulk exotics from flux breaking

Callaghan

King

Leontaris

2013

We consider gauge coupling unification in E 6 F-Theory Grand Unified Theories (GUTs) where E 6 is broken to the Standard Model (SM) gauge group using fluxes. In such models there are two types of exotics that can affect gauge coupling unification, namely matter exotics from the matter curves in the 27 dimensional representation of E 6 and the bulk exotics from the adjoint 78 dimensional representation of E 6 . We explore the conditions required for either the complete or partial removal of bulk exotics from the low energy spectrum. In the latter case we shall show that (miraculously) gauge coupling unification may be possible even if there are bulk exotics at the TeV scale. Indeed in some cases it is necessary for bulk exotics to survive to the TeV scale in order to cancel the effects coming from other TeV scale matter exotics which would by themselves spoil gauge coupling unification. The combination of matter and bulk exotics in these cases can lead to precise gauge coupling unification which would not be possible with either type of exotics considered by themselves. The combination of matter and bulk exotics at the TeV scale represents a unique and striking signature of E 6 F-theory GUTs that can be tested at the LHC.