Let us discuss the scanning over the model parameters. Electroweak tests are generically satisfied for our choice of IR scale 1 /R ′ = 1 . 5 TeV, as expected for UV localized light fermions [15] (with partial protection of universality for Z couplings). The constraints from tree-level LFV are also typically mild, due to the double layer of flavor protection in our model. Among the processes considered only µ → eee and µ − e conversion are close to current experimental limits. In our general scan up to ∼ 70% and ∼ 51% of the points pass the corresponding bounds, respectively. 8 The main constraint turns out to arise from µ → eγ . In general the new contributions are smaller for smaller values of v/ Λ and relatively large values of c$_{3}$ . On the other hand, the departure from TBM mixing is somewhat sensitive to the value of v ′ / Λ ′ , decreasing with this ratio. Thus, in the following we fix v ′ / Λ ′ = 0 . 05 to ensure a nearly correct neutrino mixing, passing ∼ 82% of the points the PMNS test when varying the other parameters. These are randomly selected with 0 ≤ v$_{η}$/ Λ , v ′ $_{η}$/ Λ ′ ≤ 0 . 3 and c$_{3}$ ≥ 0 . 5. v/ Λ is computed from Eq. (45). In the Figure we show the most restricting observables as a function of this ratio, together with the corresponding current experimental limit (solid line). These are µ → eee (top-left panel), µ − e conversion in nuclei (top-right panel) and µ → eγ (lower panels, with the full range of v/ Λ on the left and only small v/ Λ values on the right), for which we have also drawn the expected sensitivity from MEG (dashed line). The extra flavor protection of tree-level mediated processes in the top panels relative to the one-loop µ → eγ decay can be clearly observed in the Figure. As we see, a large number of points passes the different tests for relatively small v/ Λ values. If we restrict ourselves to v/ Λ ≤ 0 . 05, about 97% of the points pass the µ → eee and µ − e conversion tests, whereas 61% satisfy the µ → eγ bound (and only 28% the expected MEG sensitivity). 

We collect in Table II the percentage of points that satisfies all the experimental tests for different ranges of c$_{3}$ and v/ Λ. Requiring c$_{3}$ ≥ 0 . 55 and v/ Λ ≤ 0 . 05 we find that 91% of the points pass all current experimental constraints (53% if we include the projected MEG sensitivity on µ → eγ ). For v/ Λ small enough, all tree-level LFV effects are negligible, and the only (mild) constraint comes from µ → eγ . Note, however, that in our scans we have randomly selected order one values of the dimensionless couplings and fixed the global scale through the ratios v $^{(}$′) ( η $_{)}$/ Λ $^{(}$′$^{)}$. The unbalanced sensitivity of µ → eγ forces the global scale to be small, and then all other effects are almost negligible, including deviations from 

