Fermion Hierarchy from Sfermion Anarchy

TL;DR

This paper proposes a minimal supersymmetric model where hierarchical fermion masses arise from loop processes involving anarchic sfermion matrices, matching observed patterns with some discrepancies.

Contribution

It introduces a novel mechanism generating fermion mass hierarchies from sfermion loops without requiring symmetries or small parameters.

Findings

First and second generation masses generated at 1-loop

Hierarchy between first and second generations achieved naturally

Model compatible with gauge and Yukawa unification with simple modifications

Abstract

We present a framework to generate the hierarchical flavor structure of Standard Model quarks and leptons from loops of superpartners. The simplest model consists of the minimal supersymmetric standard model with tree level Yukawa couplings for the third generation only and anarchic squark and slepton mass matrices. Agreement with constraints from low energy flavor observables, in particular Kaon mixing, is obtained for supersymmetric particles with masses at the PeV scale or above. In our framework both the second and the first generation fermion masses are generated at 1-loop. Despite this, a novel mechanism generates a hierarchy among the first and second generations without imposing a symmetry or small parameters. A second-to-first generation mass ratio of order 100 is typical. The minimal supersymmetric standard model thus includes all the necessary ingredients to realize a fermion spectrum that is qualitatively similar to observation, with hierarchical masses and mixing. The minimal framework produces only a few quantitative discrepancies with observation, most notably the muon mass is too low. We discuss simple modifications which resolve this and also investigate the compatibility of our model with gauge and Yukawa coupling Unification.