Effective theories of flavor and the nonuniversal MSSM

Abstract

Flavor symmetriesà la Froggatt-Nielsen (FN) provide a compelling way to explain the hierarchies of fermionic masses and mixing angles in the Yukawa sector. In Supersymmetric (SUSY) extensions of the Standard Model where the mediation of SUSY breaking occurs at scales larger than the breaking of flavor, this symmetry must be respected not only by the Yukawas of the superpotential, but by the soft-breaking masses and trilinear terms as well. In this work we show that contrary to naive expectations, even starting with completely flavor blind soft-breaking in the full theory at high scales, the low-energy sfermion mass matrices and trilinear terms of the effective theory, obtained upon integrating out the heavy mediator fields, are strongly non-universal. We explore the phenomenology of these SUSY flavor models after the latest LHC searches for new physics.

Flavour in SUSY after LHC

“…In this work, building on the methods of [3], we continue to analyze the flavor structures in supersymmetric theories where the MSSM arises as a low energy effective theory from a flavor symmetry broken at higher scales. For a specific class of predictive models, if the scale of mediation of Supersymmetry breaking is above the flavor symmetry scale, the resulting flavor structures in the soft-breaking terms are not universal and can give rise to flavor changing effects at low energies.…”

“…In this section we review and update the results of our previous work [3], demonstrating that in SUSY models augmented with a flavor symmetry spontaneously broken at a scale Λ f ≤ Λ S , flavor violation in the soft-breaking terms is generically present in the low-energy effective theory. This remains true even starting with completely flavor blind soft-breaking in the full theory and runs contrary to the naive expectation that the soft terms, being controlled by the flavor symmetry, should be diagonalized by the same rotations which diagonalize the Yukawa couplings.…”

“…Although, in all generality the MSSM contains a host of unknown parameters in the flavor sector, in a previous work [3] we explored a specific class of predictive models where the MSSM emerges as an effective theory from an ultraviolet flavor-symmetric theory. These models :…”

“…Here, we investigate this class of models [3,4,5], with a particular emphasis on constraints coming from leptonic flavor observables such as µ → eγ, µ → eee, and µ − e conversion. We look at two representative models, based on the symmetry groups ∆(27) and A 4 .…”

Lepton flavor violation and neutrino masses from A5 and CP in the non-universal MSSM

“…Another possibility is Supersymmetry (SUSY), which we consider the perfect example for this as it generically contains new flavor interactions in its soft-breaking sector in the presence of a flavor symmetry. As shown in [20][21][22][23][24], non-trivial flavor structures are unavoidable if the scale of transmission of SUSY breaking to the visible sector, Λ SUSY , is larger than the scale of breaking of the flavor symmetry, Λ f . The group A 5 combined with the so-called generalized CP symmetry has already been studied in different contexts [25][26][27][28][29].…”